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Mach Discussion => General Mach Discussion => Topic started by: Hood on January 03, 2016, 06:00:20 PM

Title: Physical buttons for plasma
Post by: Hood on January 03, 2016, 06:00:20 PM
I am about to build a plasma table, having never used a plasma before I was wondering what buttons I should have on my panel.

I will have Start, Stop, Feedhold and reference(Home) buttons and feed override pots  and axis select for MPG.
What other buttons would a plasma want?
Thinking one for finding the material surface, not sure if that is normal though?
Anything else?


Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 03, 2016, 10:30:45 PM
HI Hood, Yes a TOM button , a THC on/off button, Zero all button , and it depends on what you setup for teh functions for Plasma. It can run from a simple cutter or a complex cutter with many plasma functions and adjustments both to teh software and hardware.

An example of a handy set of buttons would be run extents , a routine to dry run teh outside contour to verify the part fits the material. Then there is offset right and offset up, routines to offset the part to the right side extents so that you can cut a second part quickly and the OffsetUP which does the same only in the up direction.

Then there is teh G68 part rotate.

There are a lot of interesting and time saveing functions so it just depends on what you want or need from Plasma.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 04, 2016, 06:19:36 AM
Thanks TP, not sure how much I would use the rotates and offsets as likely I would do most in CAM but as I have never used Plasma before. However  maybe I better think about leaving space there just in case I would use them.
Maybe also an AntiDive On/Off button? Then again maybe that is taken care of in the THC, will have to look.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 04, 2016, 01:21:41 PM
Hood, curious to know what THC you decide to go with.
(Curiosity not bun fight)
Thanks
Title: Re: Physical buttons for plasma
Post by: Hood on January 04, 2016, 01:29:45 PM
Just went with one I found from a Russian guy, never seen it before but looked decent enough.
Time will tell.
Here is the link.
http://www.ebay.co.uk/itm/321675169858?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Hood
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 04, 2016, 02:09:06 PM
Its great to see you starting another adventure Hood, and happy to see that you are inviting us along !
Looks to be very comprehensive documentation with the THC mentioned. One of the most important things to look for initially.

Which plasma unit (mfg) are you planning ?

I started to build a plasma table myself some time back using Hypertherm, I might just revisit that project now that I will have you to follow ... (if I can keep up).

Looking forward to it.
Best wishes for the new year.
Regards,
Russ   :)
Title: Re: Physical buttons for plasma
Post by: Hood on January 04, 2016, 02:21:26 PM
Yes, the manual was what drew me to that one, plenty Chinese ones on eBay but documentation is poor if there is any at all.
I also emailed the guy, he speaks (or types I suppose ) brilliant English and was very helpful, in fact he suggested I may not actually have to buy the stuff from him as CS-Labs have a software THC.

The plasma I was thinking about was a hypertherm 65 but went with a TecArc Opticut 65 instead. I have their 251 Tig and it has been a nice machine, so decided to go with their plasma.
Here is a vid of it.
https://www.youtube.com/watch?v=Hmj6JlfZUeo


I have wanted a plasma table for a long time, just don't have the room. Got some rails and racks from a glass cutting saw that a fiends work scrapped so decided I had to put them to use. Still dont have the room but I should manage to squeeze it into the porta-cabin out the back of my workshop.

Here's  what I have drawn up so far.

Hood



Title: Re: Physical buttons for plasma
Post by: Overloaded on January 04, 2016, 02:38:59 PM
Impressive demo video indeed !
Amazing how the torch doubles as a chipping hammer on that Hardox.  :)

Looks like a robust machine .... nice table plan too.

Thanks,
Russ :)

Title: Re: Physical buttons for plasma
Post by: Hood on January 04, 2016, 02:41:50 PM
Yes, rough barstewards they are in Yorkshire, just ask Graham ;) Even worse than us Scots.

Hood

Title: Re: Physical buttons for plasma
Post by: Overloaded on January 04, 2016, 02:50:53 PM
 :D

I will, if I see him in Lebanon this year.
Wondering if anyone from NFS will even be there though  ::)

Russ
Title: Re: Physical buttons for plasma
Post by: Hood on January 04, 2016, 02:59:12 PM
Not a clue Russ, not spoken to any of them for a year or more I suppose.

Hood
Title: Re: Physical buttons for plasma
Post by: Chaoticone on January 04, 2016, 09:19:15 PM
Looks good Hood, glad to see you building one.  :) That fella in the demo is just showing off.

I know you can put the sheets where you want them (with one arm) but would think a button to set the alignment would be real handy. What size is the table?

Brett
Title: Re: Physical buttons for plasma
Post by: RICH on January 05, 2016, 06:51:24 AM
Consider just using even spaced nails instead of the bars in the basin. Easy replacement if cut through.
That's what my friend did when he built his. Have a drain on the bottom pan to get rid of the water.
A cheap exhaust fan using pvc pipe for duct with 4 clear vinyl draw down curtains keep any fumes in location. Not sure how big, but, a base / legs  for it which folds along with casters allow you to store upright and get out of the way when not in use.
Consider using the base along with a lip to hold a spoil board and making an attachment for a router....now you can have a multi purpose machine.

FWIW,
When the floor and sides of the room provide no room it's time to use the ceiling. :D
I also add that, try as I may, you just can't put 2 ft3 into 1 ft3....but dumbo here still tries! ;D

RICH

Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 11:45:01 AM
Brett,
  was thinking of designing some sort of roller system that raises/lowers and have a reference stop for X and Y. Or maybe even using the gantry with some suction cups, have a big vacuum pump waiting for a job :)
The table is 3070mm wide (my cabin 3150 :D ) and 2000 long. The sheet shown on the table is 2500mm x 1250mm (8' x 4')

Rich,
 will have a drain in the tray, as for the fan, the cabin is full of holes and the gales are constant here :D

Not sure what you are meaning by  nails or rather the fixing method you would use.
 The slats are just slid in so easily replaced.

Hood
Title: Re: Physical buttons for plasma
Post by: Chaoticone on January 05, 2016, 11:53:01 AM
Quote
(8' x 4')

Good! I'm so glad to see you building one and I am most interested in how much you use it/like it in a years time. If my rich uncle had got out the poor house 10 years ago you would have had one then (hes still not out BTW). I just think you will get a lot use out of it. I can hardly wait to see some of the work you will produce with it.  :)

You settled on motors and drives yet?

Brett
Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 12:45:06 PM
Yes I am sure I will use it a lot, just simple things mostly.
I make a lot of bits and pieces for the boats out of sheet/plate and at the moment I mill them which takes time as it is mainly 316 stainless. With this it should make these bits easy and save on snapped carbide cutters :D

Will be using the spindle motor/drive and Z axis motor drive from the wee lathe and have another motor on its way from eBay.
So 400watt Samsung for Z.
600w Allen Bradley for Y
1.2Kw Allen Bradley for X.

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 05, 2016, 02:55:16 PM
When Hood starts using it THEN he will understand the want/need of special buttons and functions. Even the Conversational SHAPES page to be able to cut common shapes to size without CAM is a great helper for one'sy twosy's . Then when you really need 5 of those the offsetright/upbuttons come into play. To cut the 2nd part you selct which direction to offset in and it auto positions it to teh edge of the last cut and you simply push teh GO button for the next cut, repeat until you have 5 cut . In most of those cases I can have them all cut before you get off of teh Cad/Cam drawing board.

Teh rotation really shines when you have to cut 1 part from a previously cut sheet that has room left on it but not in teh orintaion needed to fit teh part. That is when IF you could rotate the toolpath  say 10 degrees it would fit perfectly . This saves a lot of time over redrawing it in cad/cam to fit.  AND yes IF you could easily rotate teh sheet you could cut it but large sheets do not rotate far on a table. The reason for leaving it in large sheets is it is much more stable laying on the table that a small sheet.

BUT those are the things you learn with experience. You will love having the table when you need it.

ONE note , put it as far away from any machine tool you have as possible. a seperate building /room is best .The micro metalic dust it puts off will eat your Mill and lathe slides alive and in a short time. Once teh slides get contaminated it is almost impossible to get them clean again. The dust imbedes into the metal and is very hard to get out.

That same metalic dust will also KILL an electronic control board/PC  in short order. 

(;-) TP

Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 05:00:07 PM
TP,
 yes I am sure I will find these things handy once I get into the way of using it. I will have space for 8 physical buttons so will just place them in the panel and probably configure them at a later date.
 It will be a touch screen so I can also add onscreen buttons if need be.

It will be in an old GRP cabin out the back of my workshop and the only stuff in there will be the cutter and the metal I store in there, so no probs with machine ways, well except from the plasmas :D

Out of interest, which method do you use for finding the material?
I will be using the CSMIO/IP-S (removed from small lathe) as the controller so I will have the ability for index homing, so could use that with a floating torch or I could use the probing routine, but just wondering what method you, or others that have experience with plasma, use?

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 05, 2016, 05:09:40 PM
HIYA Hood I use a floating Z switch and G28.1 BUT teh G31 will work equally as well and does have a couple of advatanges IF you refhome the machine. IF you are doing very light guage cutting you may want to consider an Ohmic touch off system as it does not flex the sheet goods on touch off. BUT keep the Zswitch as a safety back up to teh ohmic as the Ohmic is not always 100% certain to touchoff.

IF you are cutting thicker plate I see no advantage either way for what you are needing.

(;-) TP

Title: Re: Physical buttons for plasma
Post by: robertspark on January 05, 2016, 05:10:22 PM
Floating head for me.

Considered ohmic (from the same seller and also shad at neuron THC (nice controller)... But as was pointed out to me if you have a coating or surface rust they can be... Not problematic ...just not so sensitive.

Mine is a 4x4 hobby machine with a small older hyperthem.  I'd buy a 45 if I were you... Not sure how that compares with your proposed non hypertherm 65 for cut quality.
Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 06:06:56 PM
TP
 most of the stuff I will be doing is in the 4mm to 20mm range in  Alu and 2mm to 20mm Stainless, so the plate bending shouldn't really be an issue, or at least I hope it wont be :D
I asked the russian guy that I am getting the THC from, about the Ohmic sensor he sells and he said he didn't think the torch I will be getting would work with it. I may however get a machine torch at a later stage so could look at it if need be.

Rob
 I looked at the 45 and thought it was a bit too small for what I need. It was a toss up between the Powermax 65 and three from TecArc, the 65, the 95  and the 125. Decided the 95 and 125 may be too big for what I want so I ruled them out.
 So it was the Hypertherm 65 or the OptiCut 65, the capacity and duty cycles were about the same (the Opticut fractionally  better on some).
 The Hypertherm was more expensive but that wasn't a major consideration as I tend to try and only buy once. I spoke to someone who has used both and he rated the Opticut a better machine and he is a Hypertherm owner, so decided to go with it.
 I am also not a big fan of Inverter technology, the lifespan tends to be lower, or certainly is with TIG. The only Inverter plasma I would consider is a  Hypertherm as they get a good name for life. The Opticut however has a transformer at its heart so hopefully will be more rugged. The Tig I have certainly is more rugged than the Inverter based one  I had previously.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 05, 2016, 06:29:45 PM
Thanks for the info hood, I'm keeping my eyes open for a bigger capacity machine hence appreciate the info, as the UK market seems flooded with Chinese made ones that aren't suitable for machine cutting and the longevity, information (cut speed tables) and owners plus parts manuals and replacement bits are zero.

Ohmic sensor has an insulated cap (best solution) or a fabricated insulated ring with a spade connector ... If you type in hyperthem or thermal dynamics and ohmic sensors into Google searching images there are a few variants of the same thing or principle about.  I know both of them offer an ohmic solution specifically, not seen any others though.

The hyperthem 65 and 85 offers modbus control of the plasma as well as the machine interface which I like the idea of... But I'd need to get one direct from the states as single phase.  Other than filtering I cannot see why a single phase ce hyperthem is not offered.... Or why it really wouldn't work.

I'll keep my eyes open for any machine cuts you post as I'd be interested to see the edge finished cut on the opticut 65.
Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 06:44:14 PM
If only single phase then make sure you have the capacity as I think the Hypertherm 65 needs 40 or 45 Amps. The Opticut 65 is 32 Amps.
 I went for the dual voltage one as I have 3 phase so if I take it round to a boat in the harbour I can run off a 3 phase supply (use 2 phases) In fact that is what I will run it on when on the table.

They tend to build the Opticuts to order so I have to wait 7 working days. I ordered 2 days before Christmas and they just started back yesterday, so probably next Monday or Tuesday when I get it. I could have had a 95, that they had in stock, the next day but it was a single phase model, more expensive, probably a bit too big for my needs but the deal breaker was it needed a 64 Amp supply.

I will just be using it to hand cut for a while, have quite a bit of work on at the moment so no time to build the CNC.


Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 05, 2016, 06:46:39 PM
Oh forgot, TecArc seemingly can offer CNC Interface boards in the machines but that is an option. Don't know what it consists of or the price though.
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 17, 2016, 02:34:28 PM
Got the plasma cutter on Wednesday night and spent the next day making a mess of metal :D

I don't know how I managed without it before :D
I tried various settings and various metals and it works great.
Cut 3mm up to 20mm Alu,  4mm up to 16mm stainless and 2mm up to 32mm steel and it was amazing to use.

Just wish I had the time to get the table built straight away, sadly that will have to wait a while as I have a fair amount of work on at the moment.
Have been using it for one of these jobs, cutting 10mm alu sheets up, it is like a knife through butter, cut a section with it that took maybe  5 mins to do, would have taken me near an hour with a grinder I think.
Cut a hole in the centre of the section, 150mm dia, just milled a thin piece of alu out at 160mm internal dia and used that as a template, piece of cake :)

CNC will make things much neater and easier though :)

Hood

 
Title: Re: Physical buttons for plasma
Post by: Hood on January 17, 2016, 02:36:42 PM
Oh also got the THC from Russia, hooked it up to the CSMIO here at home (been wiring the panel up here ) and it seems to work well, certainly in test mode it responds very quickly but I suppose the real test will be when its hooked up and controlling a real axis.
Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 17, 2016, 03:06:28 PM
Thanks for the update, I for one will be very interested to know how it works on thin and thick stuff (high and low cutting speed)
Title: Re: Physical buttons for plasma
Post by: Hood on January 19, 2016, 07:39:05 AM
What are people thoughts on having a water table?

I have been trying to work out how I can get the table into the back section of my workshop and it would be extremely tight with the bandsaw and the plasma. If I did away with the water table and just has a portable grid of 2500mm x 1250mm that I could pull forward when I am using the plasma it would make things a bit less cramped.

Pics below of with and without the water tray. In the second pic the grid would be in this position when not using.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 19, 2016, 07:48:35 AM
Are you doing stainless?  If so, I thought a water table was beneficial to avoid blackened edges (so is the use of nitrogen I think it is).

Is it a workplace (as classified by hsawa 1974....)... In that case you would need to consider hsg 258... (Search hsg 258 PDF and you can download the guide for free).

A downdraft chute will also work ... But not on stainless edge quality or blackening (think the grade of SS may be an issue)

Not done SS myself, just read titbits
Title: Re: Physical buttons for plasma
Post by: Tweakie.CNC on January 19, 2016, 07:58:09 AM
What are people thoughts on having a water table?

I have been trying to work out how I can get the table into the back section of my workshop and it would be extremely tight with the bandsaw and the plasma. If I did away with the water table and just has a portable grid of 2500mm x 1250mm that I could pull forward when I am using the plasma it would make things a bit less cramped.

Pics below of with and without the water tray. In the second pic the grid would be in this position when not using.

Hood

I think you need the unit next door as well.  ;D
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 19, 2016, 08:23:11 AM

I have been trying to work out how I can get the table into the back section of my workshop and it would be extremely tight with the bandsaw and the plasma.   
 
Hood

Wondering just how much the new Plasma would negate the need of the saw. If illustrated to scale (as probable to the micron) that is a bear of a saw.
I'd try to leave the plasma table in place and put the saw on casters/rollers and roll it from the wall when needed. (casters, or surplus railroad bogies  :) ).

Or maybe downsize the saw ? ? ?

Either way, I would give the plasma table permanent resident status .... water table or not.

Guess it all depends on projected usage of each.

Russ
 :)
Title: Re: Physical buttons for plasma
Post by: robertspark on January 19, 2016, 10:44:38 AM
Oh ... Water table... Is the shed heated (thought I saw the word portacabin somewhere...not sure of the chances of freezing in an unheated shed in scotland)... Also if it's not being used much, consider corrosion (add inhibitor) and bacteria (add a biocide), could always design it to take a water table later if your material throughput justifies it.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 19, 2016, 10:57:57 AM
HIYA Hood What controller will you be using with the plasma table ??

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Chaoticone on January 19, 2016, 11:09:36 AM
What are people thoughts on having a water table?

I have been trying to work out how I can get the table into the back section of my workshop and it would be extremely tight with the bandsaw and the plasma. If I did away with the water table and just has a portable grid of 2500mm x 1250mm that I could pull forward when I am using the plasma it would make things a bit less cramped.

Pics below of with and without the water tray. In the second pic the grid would be in this position when not using.

Hood

I think you will want a water table Hood. Probably as much as doors on the Chiron. I imagine you will be keeping it hot. They can generate a lot of slag and smoke quick fast and in a hurry.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 19, 2016, 11:54:32 AM
For occasional cutting a water table is a pain in the rear end . Being it would be in an unheated shed in Scotland it would be a double pain in the rear end.

Use a slide in pan to catch teh slag/drops and a good exhaust fan to evacuate the fumes.

NOW if it was to be used in continuous productions cutting that would be a different story AND it would NOT be out in a shed.

Just a thought, (;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 19, 2016, 02:04:49 PM
Thanks for all the replies, I will try and answer all as I go.

Are you doing stainless?  If so, I thought a water table was beneficial to avoid blackened edges (so is the use of nitrogen I think it is).

Is it a workplace (as classified by hsawa 1974....)... In that case you would need to consider hsg 258... (Search hsg 258 PDF and you can download the guide for free).

A downdraft chute will also work ... But not on stainless edge quality or blackening (think the grade of SS may be an issue)

Not done SS myself, just read titbits


Any stainless I have seen that has been cut on a plasma has blackened edges, still nice clean cut and easily buffed but  would a water table help with that?
Would the plate be submerged? Most of the ones I have seen is with the water below the material although I think I do recall, maybe an Esab video, with the material fully submerged.

Regarding health and safety, it is a workshop but I am the only person there so I don't think they have any jurisdiction, I do take my health seriously though, well now I am getting older and feeling the effects of not doing so in my younger days :D



I think you need the unit next door as well.  ;D

I already have two units and the only other 2 are occupied and anyway not everyone is a rich kid like you and Brett, so wouldn't be able to afford it even if empty :D

Wondering just how much the new Plasma would negate the need of the saw. If illustrated to scale (as probable to the micron) that is a bear of a saw.
I'd try to leave the plasma table in place and put the saw on casters/rollers and roll it from the wall when needed. (casters, or surplus railroad bogies  :) ).

Or maybe downsize the saw ? ? ?

Either way, I would give the plasma table permanent resident status .... water table or not.

Guess it all depends on projected usage of each.

Russ
 :)

Russ I reckon it will have very little effect on the bandsaw use, more likely it will be the Chiron that gets less use.

It is a fairly big saw but not massive, 280mm jaw opening and think 250mm Dia.

No way I will be downsizing the saw, need all of it's capacity and could often do with more :D

I was planning on putting it on wheels, the position in the pics is when I will be using it for cutting up long parts, the door nearest the saw is the outside door and the other one is through into the section I have my desk and Beaver mill, it was one unit but I sectioned it off. Often I have 6m lengths of material being cut and they are  right through the two doors :)

The plasma will be permanent there, it is just whether to build the  table section or just have the two side rails and have a 2500 x 1250 (8' x 4') grid which I can slide back a bit as in the second pic, freeing up some space when not in use.
Just thinking though, if I had the moveable grid/table/whatever its called just 100mm bigger than a sheet I could still have the water underneath and  still gain the room if it was pushed back.


I think you will want a water table Hood. Probably as much as doors on the Chiron. I imagine you will be keeping it hot. They can generate a lot of slag and smoke quick fast and in a hurry.

Sounds like you know what you are talking about Brett :) Is that where you do all your cooking? :D


HIYA Hood What controller will you be using with the plasma table ??

(;-) TP

Will be using the CSMIO/IP-S controller I have pulled off the wee lathe.

For occasional cutting a water table is a pain in the rear end . Being it would be in an unheated shed in Scotland it would be a double pain in the rear end.

Use a slide in pan to catch teh slag/drops and a good exhaust fan to evacuate the fumes.

NOW if it was to be used in continuous productions cutting that would be a different story AND it would NOT be out in a shed.

Just a thought, (;-) TP


I am trying not to put it outside in the shed, trying my hardest to fit it into the backmost section of my workshop. Still bloody cold at times, only heating there is when I fire up the pipe and have a smoke :D

It is unlikely to be continuously cutting but I do see it being used a fair amount, time will tell though.

So  the benefits of a water table are what?
To cut down on fumes?
To reduce heat?
Anything else?

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 19, 2016, 02:17:30 PM
Have a read here on nitrogen, and stainless plus the use of a water table... Although it's a submerged cut

http://www.hypertherm.com/en/Torches_and_consumables/Centricut_consumables/Centricut_plasma/Articles/article_ChoosingPlasmaGases.jsp
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 19, 2016, 02:21:50 PM
Ahhh ... OK.
I was assuming it was a vert. saw.
Gotcha now.
My horiz. saw is 280 x 460 cap. and is on casters, very handy that way.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 19, 2016, 02:29:08 PM
http://www.modernmetals.com/item/11600-underwater-plasma-cutting.html

I have a foldup and extendable table.  Garage isn't that big, hobby for me.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 19, 2016, 02:42:35 PM
Submerged cutting is a whole different animal . (;-)

(;-)TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 19, 2016, 03:19:53 PM
I started off with a water tray on my first machine, PITA TBH.

I only cut occasionally 2-3 times a week. On the new table i fitted a large (350mm) duct extractor under the table making it a down-draught one. The fan exhausts through the garage wall, I have to open a window when cutting or the vacuum makes your ears bleed (well not quite but you get the idea), even with he water before, I would end up with the black-snot at the end of a day which was pretty worrying from a health point of view. With the extract, I can cut all day and not even smell it :)

If you do go with extract, make it down-draught as fitting the extract above is not as good.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 19, 2016, 04:04:16 PM
For any draft... Go with the direction of flow... Which is generally downwards for a plasma (only ever seen one vertical plasma table). 

If you do go for a fan ... Look for something like a mixed flow fan and not just an axial fan as they have a higher discharge pressure for ductwork (flexible or ridgid)

(Dayjob tips)

I did sandblasting in the garage once upon a time... Best thing I ever did was build an enclosure using PVC drainage pipes with 1000 guage plastic sheeting and a 12" vent axis powerflow fan.... No dust ever escaped the enclosure (I used an air fed blasting helmet whilst sat in it for the time it takes to discharge a 50 litre pressure pot blaster full of 60/40 garnet... Vaccumed up using an old dyson for reuse as the cyclone separates out the fines....  Sorry off topic more to give an example of fan flow.

If you want to make an angled chute below the table for iron filings collection, need to consider the angle of response for iron filings... Which I think is about 45 degrees, hence I would split the underneath of the table in two and create 2 4' chutes, with an easy to empty iron filings tray at the bottom of each chute set as a drawer and a 12" extractor fan connected near the bottom of each chute, except you want the chutes to decrease in size to a sort of cone shape, then have an abrupt expansion where your drawer is, so that the air velocity drops off drastically and any suspended particles in the airsteam loose suspension and end up in the drawers.

Just another option to consider.

What I did with my slats is I got some 15mm SHS, and welded it to the end of some wide flatbar 50x3, which was cut in a chopsaw about 3" longer than my bed gap.  On the table railsi welded a 50x50 angle iron at either end and then aload of 15x15 SHS teeth vertically which had a gap between them of about 20mm.  Then I force and bend the slats in and they interlock, and they snake across the bed in a curved profile.  They can be removed, flipped over, swapped or put closer together or further apart as nessesary.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 19, 2016, 04:04:50 PM
HIya Hood did you realize that that controller has a real analog THC function built in and you don't need an outside THC controller (;-) You just input teh divided voltage under 10V and it can do all the THC work realtime.

There are a ton of really cool things you could do with it for plasma. I have been wanting to test one but am too cheap to buy one to test(;-) They could capture a HUGE share of the CNC plasma market with that controller IF it actually works well.

Are you going to run it with Mach3 or Mach4 ??  (;-)  

(;-)TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 19, 2016, 05:55:19 PM
Ok thanks for the info, looks like the water table is out, especially after reading the links provided by Robert. Never even thought of the hydrogen issue with Alu and water. I will be cutting  mainly Alu and Stainless seeing as I do marine stuff.

Will just go for the sliding rack so that I can push it back against the wall when not in use, will free up almost 1 meter x 3 meters.

Will have to look into the fans, don't have any experience at all, may initially use a fan I kept from a Kemppi Mig welder as it is lying about doing nothing.

TP
Yes I did know the CSMIO had THC but my Plasma doesn't have a divider in it, it was an option but as the plasmas are built to order it would have added a day or two onto the delivery and I was really needing it ASAP.
I decided to go with the Russian THC as it has the Arc OK board and the Divider so I still have the option of using the CSMIO THC if I want/need.

Robert,
 I think I am doing something similar to you re the slats, will just have angle with bits of flat bar 90mm or so welded to the angle with a 3-4mm gap between them so the slats fit in.

Hood
Title: Re: Physical buttons for plasma
Post by: Chaoticone on January 19, 2016, 08:44:27 PM
Quote
I already have two units and the only other 2 are occupied and anyway not everyone is a rich kid like you and Brett, so wouldn't be able to afford it even if empty Cheesy


Tweakie, don't believe everything you hear. I'm so poor I can't afford to buy fruit. The only way we get any fruit to eat it is to peel it off the wallpaper.   ;D
Title: Re: Physical buttons for plasma
Post by: Tweakie.CNC on January 20, 2016, 01:56:52 AM
 ;D ;D ;D

Tweakie.
Title: Re: Physical buttons for plasma
Post by: Hood on January 20, 2016, 03:31:24 AM
Wallpaper?
Your just showing off your wealth there.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 20, 2016, 03:31:57 AM
TP,
 forgot to answer you earlier, it will be Mach 3.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 20, 2016, 05:46:32 AM
Can I ask if anyone is using Mach4 for plasma?

The only screenset I've seen for Mach4 is from vital systems for their Hicon controller, and presume it can be adapted.... but it would require a compatible motion controller.
http://www.vitalsystem.com/portal/cnc/motion/plasma.php (screenset download link in top RHS list, copied below)
http://www.vitalsystem.com/portal/cnc/motion/ArcPro_Plasma.zip

I'm awaiting Warp9 to release their updated M4 plugin to hopefully turn on the THCUP, THCDN, THCOK functionality (M62 and M63 wiould be helpful for me too [as a quick THC ON / THC OFF toggle via relay + routing the THCOK signal back to the ESS]) hence can't do anything until this point unless I change motion controllers.

Does anyone believe that M4 is missing something that won't work with plasma or wont work well, or could do better?

50Hz script loop (adjustable) has got to be better than the 10Hz brains or macropump.

A plasma screenset would be nice from Artsoft to get us started.

The use of the Analogue Input on the CISMO for THC with Mach3 via THC Plugin, what loop speed does it run at?  (10Hz for THC at high cutting speeds may be a little slow to correct?)

Rob
(always here to learn.... thanks)
Title: Re: Physical buttons for plasma
Post by: Hood on January 20, 2016, 07:02:58 AM
The THC in the CSMIO would be done within the motion controller I would think, so would be extremely fast, probably in the high KHz if not MHz.
Regarding Mach4, not tried it for a long time on anything but from what I saw it was years away from being capable of what Mach3 is now.
Maybe I am wrong and it has taken a giant leap in the last wee while, hope so.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on January 20, 2016, 12:04:47 PM
Hi Rob - Not sure if I'm misreading what you're saying here but Mach3's THC loop is WAY faster than 10Hz. I've tested it (Mach3) to 2KHz with my THC and it keeps up no problem at all. The scope traces are on here somewhere for the last time someone came out with this 10Hz thing. I'll find them and re-post if it helps.

Ian

Title: Re: Physical buttons for plasma
Post by: Hood on January 20, 2016, 12:17:45 PM
Ian, I looked at your THC but  seemed it was only for Hypertherm cutters, did I get that right?

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 20, 2016, 01:23:12 PM
An outside controller MUST do all the THC functions internally.  IF you are to do teh analog monitoring as well it must sample at a rate to provide usable data at the max feedrate you will be cutting at.
One of the nice things about teh Controller doing ALL teh functions is it is easy to update teh variables for the THC function on the fly( set volts, Antidive,Cornerlockout, THCdelay,etc). You already have a Com link to the controller so no other outside com link is needed. Also easy for the controller to update teh User Displayed values such as Arc Volts.

Title: Re: Physical buttons for plasma
Post by: BR549 on January 20, 2016, 01:38:47 PM
The one thing about teh CSlabs version that I do not care for is it requires you to adjust the Set volts via a Manual pot.   THAT should be an adjustment you make via software not not manually via hardware.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: stirling on January 20, 2016, 01:43:52 PM
Ian, I looked at your THC but  seemed it was only for Hypertherm cutters, did I get that right?

Hood

Yep - correct - well I suppose yep(ish) - any plasma that has an interface providing a 50:1 scaled voltage, a TTL arcok and a "dry contact" trigger should work in theory but it's not easy to get the specs. At the time I designed it I was only aware of HT doing this. One guy reckoned it works with a Thermal Dynamics but I couldn't get much out of him so I lost interest and just say Hypertherm only for a quiet life.  ;D

Ian
Title: Re: Physical buttons for plasma
Post by: robertspark on January 20, 2016, 02:42:20 PM
The one thing about teh CSlabs version that I do not care for is it requires you to adjust the Set volts via a Manual pot.   THAT should be an adjustment you make via software not not manually via hardware.

(;-) TP

Thanks for that I hadn't noticed....not very dynamic if you were to include something in the gcode (#parameter=?)

The best one I've seen is still the neuron THC http://neuroncnc.com/
Title: Re: Physical buttons for plasma
Post by: BR549 on January 20, 2016, 03:12:13 PM
HAve you seen Stirlings unit ?  RazorDance
Title: Re: Physical buttons for plasma
Post by: robertspark on January 20, 2016, 04:20:15 PM
HAve you seen Stirlings unit ?  RazorDance

I have seen it before, what put me off for my application was no voltage divider option or extra  (ie I had to provide a voltage divider... Or buy a bigger and newer plasma than my current older hypertherm).... I'm now waiting to take delivery of a hypertherm 65 (without CPC...to be added, plus fancy a fiddle with the rs485 interface but it would require a modbus rtu <> serial (ascii) bridge (arduino mega?))) Hence makes the razordance one more appealing for me, but no mention of mach4, hence concerned about future compatibility, website seemed a bit static so wasn't sure if it was still being supported (sorry sterling)

I'm in the UK and did seriously consider it.

Whether the neuron is worth £530 / $800... That is another matter. 

If the plugin sourcecode was available from razordance via maybe small fee and maybe NDA, now we are talking...just amazes me how much time people spend developing something, selling it, market share drops off, and they discontinue the product line but never release the sourcecode for those that may be interested (I'm thinking one man band developers here not volume sellers who reuse the code for newer products etc... Guys who come up with one off really good ideas)

One of the things that never seems to be covered is a better way to enable THC via gcode without feedrate hesitation, or instant torch firing or disabling without hesitation.  It's been my observation that every time an mcode is run motion hesitates so you end up with a divot... Except for m10/m11

Not sure what happens with #parameters added to gcode

Always learning
Title: Re: Physical buttons for plasma
Post by: robertspark on January 20, 2016, 05:08:46 PM
Hi Rob - Not sure if I'm misreading what you're saying here but Mach3's THC loop is WAY faster than 10Hz. I've tested it (Mach3) to 2KHz with my THC and it keeps up no problem at all. The scope traces are on here somewhere for the last time someone came out with this 10Hz thing. I'll find them and re-post if it helps.

Ian



Sorry Ian, missed this one.

I wasn't sure how mach3 was using Brian's torch height controller plugin, and if it was using the 10hz loop speed of brains or macropump or if it was able to use the 40hz fast loop of mach3 or if it was able to tie into the kernal (parallel port) loop speed of 25khz (or above whatever its set at)

The documentation has always been sparse on using it.

It has never been an option for me as I have never used a motion controller with an analogue input (16 bit I think is what is required), hence the only way I could get an analogue input into Mach was modbus... Which I did not believe had a very fast loop speed, hence back down to 10hz...

Did consider the uc300.. Which has analogue input support... But again no mention of the future with mach4 support.... So went the ESS route... But obviously without analogue input support... Can't win them all...

Title: Re: Physical buttons for plasma
Post by: robertspark on January 21, 2016, 01:28:13 PM
Wow, instantly gone quiet on here, I genuinely hope I have not offended, if I have I appologise.
One persons comments, viewpoint and observations were not intended that way.
Rob
Title: Re: Physical buttons for plasma
Post by: BR549 on January 21, 2016, 05:08:02 PM
NO I think it was just all covered (;-). Not much more to say. Mach3 is what it is and will never change. IF you want something better you have to move on to another brand controller (;-).

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 22, 2016, 04:28:36 PM
Ian,
 kind of thought that was the way of it. My Plasma doesn't have the divider or arc signal. There was a CNC Interface option but I never went with it as I needed the machine ASAP and I didn't bother asking how much. Suppose I really should have as I may have been surprised at the cost.


Robert
 Dont think anything you said was an issue, just as TP says I think.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on January 23, 2016, 06:28:40 AM
No worries. Although a divider etc. interface is dead easy to make, I just decided I didn't want to go near the H&S/legal nightmare of selling them.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 23, 2016, 07:01:09 AM
yeah, I guess its also warrentee issues if its not been wired up correctly... looking at the hypertherm 65, the standard voltage divider output is 20:1, and then by buying the interface card and CPC (circular plastic connector), it adds the ability via a PCB, dipswitches and presumably a resistor array to select other voltage divider settings.

https://www.hypertherm.com/Xnet/library/library.jsp?file=HYP109602
page 258 / 258, bottom RHS of schematic

One of the reasons why I like hypertherm.... the service manuals and operator manuals are available and detailed...
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 23, 2016, 11:35:47 AM

One of the reasons why I like hypertherm.... the service manuals and operator manuals are available and detailed...


Not to be advertising, but this is one of the main things I look for before purchasing. And this .doc was well worth downloading.
Thanks for the link Rob.
Hoping Hood's choice works out very well and is equally, or better detailed and supportive.  :)

All this is just helping me to prepare for the day I delve into a project similar to this .... Thanks Hood.

Hijack over ... releasing the hostages.
 :)
Russ
Title: Re: Physical buttons for plasma
Post by: BR549 on January 23, 2016, 12:47:34 PM
Could you not buy a HT voltage divider card and install it on another brand  ????   

Title: Re: Physical buttons for plasma
Post by: robertspark on January 23, 2016, 01:49:59 PM
Glad to have been able to help, note the L1 and L2 are likley to be an inductive filter.

You can build a higher voltage, voltage divider very easily.

Sorry was not really advertising, just saying as it was if another manufacturer publishes their data so fully and freely I've not seen it.  Don't work for them, sell them or even do a day job in the industry.  The operator manuals are very good too for the cut tables, which I have wondered if you can equate them to other manufactures machines, although I'd suggest as I read somewhere... Don't focus on the ampage alone but the actual cutting power... Say the machine is set at 65a/140v, so the cutting power is 9100W... Rival machine... Say 60a at 105v... Cutting power is 6300W, so proportionally the cut speed of the rival is probably going to be about 70% of the ones in the published manual... At least as a starting point if you have only an ampage and target cutting voltage without any published data..

There are obviously other bits that come into it like air pressure, inverter frequency which may affect the concentration of the plasma flame?  Arc? ... Whatever the correct technical term is of the plasma cutting zone.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 23, 2016, 02:31:39 PM
The cutting voltage is actually irrellavant. It is the cutting HEIGHT that is important. The voltage level will be what it will be depending on all the elctronics and calibration involved.  BUT teh cut charts are a great starting point.

The nice thing about the HT units are they STAY on the leading edge of plasma cutting technology. A lot of others may lag behind as much as 20 years in Plasma cutting technology and design. A lot of them are actually using OLD HT tech that the patents have run out. Most of the times even the NEW torch tech can be upgraded to an older unit.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: robertspark on January 23, 2016, 03:10:38 PM
Sorry don't agree with you there the rated cutting voltage is important as it affects the power output of the unit, and provides a simple direct comparison between machines

Wrong forum... Suggest asking over on one of the CNC forums frequented by Jim colt I know he wrote a bit on it if I can find it again I'll post it.

If you have no cut table, it can aide you in setting something up.

Compare two machine with a similar rated cutting current, say a powermax 600 and powermax 45 or a powermax 1000 and the newer powermax 65, cut tables are not the same but current maybe... Why?

Here is an article
http://www.fsmdirect.com/cutting/laser-cutting/247-volts-amps-and-plasma-power

And another
http://www.hyperthermspark.com/taking-the-mystery-out-of-air-plasma-power-supply-specifications/
Title: Re: Physical buttons for plasma
Post by: BR549 on January 23, 2016, 03:53:12 PM
I think you WILL find out differently in the real world (;-)  Even Jim will tell you two things.  Teh Amp rating sets teh power density of the plasma arc so always try to cut at  MAXIUMUM power density( 40 amp tip and 40 amp setting)  And teh Cut height is teh important value not arc voltage. They give you the arc voltage to get you in the ball park. You would set YOUR voltage value to represent teh actual cutting height listed in teh table BASED on your torch components reguardless of what your voltage display says.

Torch and tip design also plays a large part of what teh actual voltage will be cutting at a preset height.   A longer length combination of nozzle components will give you are higher voltage than a shorter length combination .

Just a thought, (;-) TP

Title: Re: Physical buttons for plasma
Post by: beefy on January 23, 2016, 04:42:28 PM
+1 to what Terry said.

Some setups have automatic voltage setting. The gcode sets up the proper cut height (the important bit) and the THC is switched off. Now, assuming your plate is nice and flat and parallel with your XY rails, the cut begins at that precise cut height, and doesn't care what the voltage is. The system takes multiple samples of the voltage for a certain time then averages those readings to give the SET VOLTS. It then passes that voltage to the THC, effectively saying, "At this cut height, feedrate, airflow, amps, etc, etc, THIS is the voltage you need to maintain your proper cut height".

That's also why the voltage can change when the electrode hafnium starts eroding away with use. This effectively increases the arc distance and hence the voltage. So as your electrode wears you need a higher arc voltage to maintain the same torch to work distance.

Another method of getting the correct voltage is to do a test cut with THC off and simply note the cut voltage. The feedrates, etc can be tweaked and the voltages noted at each test run, and the parameters from the best cut are what is used. But once again you must have a flat sheet laying parallel with your XY rails (no lumps of slag on the slats, lifting up the sheet) for these tests to be accurate.

So at the end of the day the arc volts is ONLY a representation of the cut height, which is the critical factor that Hypertherm for instance base their best quality cuts on.

If a different cut height to the cut charts gives you a better quality cut, then leave me out of that one, that's something to argue with Hypertherm, etc  ;D

Keith.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 23, 2016, 05:12:31 PM
(;-) When cutting I normally adjust to BEST cut and that does not always agree with HTs chart data. Remember that that data was derived from LAB data not real world cutting where the variable conditions can be  a lot different.

NOW most times the data is  close but sometimes NOT so close. (;-)

(;-) TP
Title: Re: Physical buttons for plasma
Post by: beefy on January 23, 2016, 06:53:42 PM
I mustn't forget that Terry.

In the days when I was learning all this stuff, one guy who cut regularly said he could use exactly the same parameters as he used on a previous day and yet the cut would not always be the same.

Temperature of the electronics changing measurement accuracy, air density/temperature, stars not aligned, who knows.

Keith.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 24, 2016, 05:19:47 AM
Yup, agree 100% lab conditions... Don't forget cutting in an in temperature regulated shed without slowly preconditioning whatever you are cutting will also result in a different cut as the material will be slightly warmer or colder relative to the plasma gas temperature (aerospace industry they precondition materials to very close temperature tolerance before machining)

The main thing is with some machines there are no cut tables so at least you have a starting point

Here is another interesting read here about controlling the cutting current whilst inhibiting z-axis motion for corners (Jim colt and tom caudle

http://www.plasmaspider.com/viewtopic.php?t=16534
Title: Re: Physical buttons for plasma
Post by: robertspark on January 24, 2016, 05:35:12 AM
Terry, if you reread my post again you will note that I was talking about machines without any cut tables published, and tried to give a bit of guidance as to how you may use a good tested and published table of cut speeds for a machine without a table of cut speeds

Zero, no tables....  Nothing ... What would you use as a starting point....

I live very much in the real world... And there are way more machines being sold without any published information than those that have good detailed manuals.... Should they be purchased... NO... But people do... And then put them on a home built CNC... Why because they are cost effective to their objectives.
Title: Re: Physical buttons for plasma
Post by: Hood on January 24, 2016, 10:21:59 AM
Hoping Hood's choice works out very well and is equally, or better detailed and supportive.  :)
Russ

Well Russ, didnt reply earlier as I had no idea what the manual was like, I never read the bloody things unless something is wroong :D

Anyway went down to the workshop today to find it, still in the poly bag that the machine was wrapped in :D
As I suspected it is very basic, few specs, info on what the buttons/switches do and thats about it. It was the same with my Tig from them, just the basics but it works great and easy to figure out in seconds.

Maybe hooking to the CNC Table will provide some issues but absolutely none so far.

Hauled off the cover and took some snaps of the internals, I am thinking the CNC interface may actually be there and all that is missing is the connector, will have a study of the pics in a wee while and see if my initial thoughts are correct or more likely post some pics and see if the clever plasma people here  think they are :D

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 24, 2016, 11:24:05 AM
Ok first pic shows section from manual about the interface.
Next pic shows what I suspect is the Arc Ok signal board, the grey wire that wraps around the board is connected to the cap at one end and goes to the work lead clamp at the other, third pic.
The circuit board seems to have missing connections on the output side of it which I think likely are for the CNC plug, 4th pic
Title: Re: Physical buttons for plasma
Post by: Hood on January 24, 2016, 11:29:11 AM
Never took a thought to see if there are wires directly connecting the circuit board to the arc voltage, all I have in the pics I took are wires from the cap to the board (pink and grey on one terminal white on other), not sure if that would be the raw arc voltage which then get divided, any thoughts?

Will likely give TecArc an email tomorrow and see what they say, in the mean time back to filling in my tax return :(

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 24, 2016, 01:33:43 PM
hIYA Robert if you have looked at some of the "others" cut values you will see MOST are not even close to HT specs (;-) And that is bascially a design issue because MOST of them are using old technology. It is simply BEST to do as Keith suggested and do a simple test cut to determene a good setting as far as height and set volts . You can figure it out in one or two simple test cuts.

Also if there are ZERO values published then the Manf does not really care about its customers (;-)

And YES I am a Loyal HT fan. And THEY have earned every bit of that respect over the years. Their HARD WORK has made my job a LOT easier and has put a LOT of money in my pocket. (;-)

IF I ever run into a weird problem I can simply call Jim and ask him about it. So far I have always gotten an answer. NOT always what I WANTED to hear but an honest answer all the same.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: robertspark on January 26, 2016, 02:38:51 AM
Agreed Terry, I'm also a loyal ht fan. (13 years now).

Ever done anything with the rs485 on the 65 and 85?
Seem to have limited themselves there providing only one board running modbus ASCII.  Asked ht Europe last week and was given a short shift answer... First time been unimpressed... Reverse engineering may be required with an arduino rtu to ASCII bridge.  ... Long term project for me maybe ...
Title: Re: Physical buttons for plasma
Post by: beefy on January 26, 2016, 06:41:51 AM
So Rob,

what did you ask HT and what response did they give.

I'm curious about the reaction time of their current control. I wonder if they publish figures like that. So from gcode to HT current adjustment via their ASCII modbus interface there will be some delay. Some of that is under our control but once the HT receives the ASCII value I wonder how long it takes for the cut current to adjust.

Keith.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 26, 2016, 08:20:02 AM
iF you are talking about on the fly amp reduction I am not a big fan with low end air plasma as you do not gain anything from it without having all teh high end features of plasma. It is more of a sales gimic than anything at this level.

You will gain a LOT more by working on the mechanics of your machine rather than the gimics of your machine.

NOW HIgh end mixed gas variable flow machines are a different story BUT that is NOT what we are dealing with.

NOW why Modbus Ascii ?? I do not have a clue only a guess.  Ascii uses a CRC check of teh code to insue it is what it is. I GUESS they wanted that type of secure mode to talk to a high end machine and it just trickled down in technology. IT DOES make it a PAIN to work with for low end stuf.

Why make it even more complicated just program your COntroller to talk Ascii.  HT shows you how to use teh CRC check.

WHY would you want more than 1 com board for teh plasma ??? 


(;-) TP
Title: Re: Physical buttons for plasma
Post by: stirling on January 26, 2016, 08:26:48 AM
NOW why Modbus Ascii ?? I do not have a clue only a guess.  Ascii uses a CRC check of teh code to insue it is what it is. I GUESS they wanted that type of secure mode to talk to a high end machine and it just trickled down in technology. IT DOES make it a PAIN to work with for low end stuf.

Hi Terry - we've discussed this before - I guess you've forgotten - check our email conversations.

Modbus ASCII actually uses an LRC whereas Modbus RTU uses a CRC. Moreover the LRC is only 8 bit whereas the CRC is 16 bit. The end result is that as far as error detection is concerned RTU is the WAY more robust than ASCII.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 26, 2016, 10:36:16 AM
Gents,

To be fair, I whole heartedly understand their position... but it would have been nice to get a bit more info.

Judge for yourselves

Question:
Quote
Hello, Looking for some technical advice or guidance, regarding Hypertherm Part number 228539 (PMX 65 / 85 RS485 communication interface). I was wondering if there was any way to change the modbus communication protocol from ASCII to RTU, or if you were developing or able to provide a MODBUS RTU protocol board? The reason being is RTU is way more common than MODBUS ASCII, hence I have cnc software which is able to directly commuicate via MODBUS RTU and I would like to employ that than using a communication interface bridge. The 228539 board obviously interfaces with J7 on the PMX65/85, is there any way I can find out what protocol or what interface takes place between the 228539 and the DSP board (141073), so I may be able to build an interface directly which could be MODBUS RTU or even MODBUS TCP/IP to gain access to the registers? Happy to sign an NDA

Response:
Quote
We only offer serial communication protocol as per the attachment, we would also not provide any other internal information on board to board protocol.

For those interested (sorry Hood, not trying to side track your topic... keep meaning to have a look at your photos on a big screen [pc])

The interface infomation is here:
http://www.cnc.info.pl/files/serial_communication_protocol_807220rev1_124.pdf


Terry, yup it's probably a "gimic" but I thought it may be handy to have if there was very little to do to incorperate it into your system.

I know that CandCNC do an interface, and compliant sheetcam postprocessor etc for this and its well documented on youtube https://www.youtube.com/watch?v=QKipXFIIg0k plus their website.

I'm over the pond, and was more curious than wanting to reinvent the wheel and I just didnt want to go to CandCNC thanks because of cost (shipping import duty etc etc etc.)

Key word.... Curiosity....

not having a go at any manufacturer
Title: Re: Physical buttons for plasma
Post by: Hood on January 26, 2016, 02:04:51 PM
Rob, no problem, nothing in my book is a hijack if it is talking about the subject even if it goes way off at a tangent.

I emailed TecArc yesterday and got a reply back, not really the info I was seeking but I suppose I never really asked a direct enough question.
Basically they said they do it as an option and they could supply parts to convert but said it would need to be done by a qualified Electrical Engineer. I asked what the parts would be and how to do but they came back saying they could supply a kind of add on which would be easier to do. What they would supply is a current sensing board  and a voltage divider board. I already have them (got with the THC) so do not see the point in purchasing more just to wire up in exactly the same manner.

I still think the divider , Arc Ok and trigger terminals are there and it would just require hooking them up but I am not going to bother trying to trace them, will just shove in the boards I have.

The THC I got has modbus on it but when I asked the guy said it really wasn't that great (too slow)  and on future revisions he will be removing it.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on January 26, 2016, 02:14:46 PM
Well the torch on and off will be easy to find.... Trace the hand torch leads obviously.

Normally the voltage sense just goes across the ground clamp (which is positive dc polarity) and the torch (negative polarity with respect to the clamp).

Only the HF off or torch cutting current signal initialised signal to find

That THC (nearly bought one) has something called "caxis protocol".... I'm curious.... What is it?.... Apparently it's a way to send settings back from the controller to Mach....or that is what I gleened from the manual

Title: Re: Physical buttons for plasma
Post by: Hood on January 26, 2016, 02:15:30 PM
Ah Ok just looked at the vid, the modbus connection you were talking about is totally different than I was thinking, it is for controlling the actual plasma current etc.
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 26, 2016, 02:22:12 PM
Yep, the connections I have to make are simple and easily accessible. The Arc signal board you c get can be cable tied to the work clamp but I will install it inside the machine and tie it to the wire that comes from the cap to the work  clamp socket. Can also get the arc voltage no probs inside and the torch trigger wires have connections I can hook into as well.
Just thought it would have been nice not to install these boards if the circuit board in the plasma already had the divider etc in it. I think it does, or at least the trigger and likely the arc signal as there are a couple of relays there.
Anyway not going to bother getting the addons from TecArc as they are exactly what I have already from the THC kit.


The Modbus in the THC is just a way of getting the Up/Down. Arc Ok etc to/from Mach instead of going via the parallel port or  motion controllers I/O.

As said I asked about it as it would have been an easy hook up but the guy said it wasn't that fast and not really suitable for thin material, so I never investigated it further.
Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 26, 2016, 04:42:39 PM
Hi Ian I agree with you (;-), the explaination I gave as a guess came about from a conversation I had with HT many years ago about their choice of Modbus.

Hiya Robert, Ok I see where you were heading GOOD idea.  Who you need to talk to is Jim Colt at HT USA. I will see what I can find out from him. I agree that an RTU version would be a BIG help or even a simple Serial version would be just fine as you are NOT accessing vary mANY variables inside of teh Plasma unit. Basically cut Amps and Air pressure.

A simple serial version may  save a LOT of overhead  over using Modbus  ?????? AND it may be that the unit actaully talks a form of serial  and they only use the Modbus board as a dependable noise free communication in a shop enviroment.

It may be that Mach3 could talk to teh unit directly across RS485.

(;-) TP

Title: Re: Physical buttons for plasma
Post by: beefy on January 26, 2016, 04:53:48 PM
Terry,

I remember you posted some time ago about having an "automated potentiometer" on your plasma cutter and you had it reducing the current at corners, etc. You said about 95% of the time it made no difference to the cut. I've often had problem on outside corners on thicker steel, and also where a lead out crosses over a lead in. I get tabs left. When the lead out crosses the lead in the arc "jumps" over to the steel on the other side of the lead in, leaving an uncut tab. Outside right angle corners have had it too, but it's more weird because the arc "RE-PIERCES" around the corner, again leaving a tab.

I was wondering if slowing down at corners may help this and by reducing the current a little bit it won't blow the kerf out noticeably wider.

Rob,

thanks for that info. I've downloaded from that link plus downloaded the other two pdfs on the protocol.

Keith.
Title: Re: Physical buttons for plasma
Post by: beefy on January 26, 2016, 05:08:27 PM
The Modbus in the THC is just a way of getting the Up/Down. Arc Ok etc to/from Mach instead of going via the parallel port or  motion controllers I/O.

As said I asked about it as it would have been an easy hook up but the guy said it wasn't that fast and not really suitable for thin material, so I never investigated it further.
Hood

I asked Jim Colt about sampling / THC signaling rate and he said most good THCs sample at least 25 times per second. I'm guessing you'd have to use a brain or macro pump with Mach3 to use Modbus so that limits the sample rate to a max of 10 times a second I believe, much slower than what Jim said. I'm working on my own THC and I have the sample rate at 32 times/sec which I could make a lot faster if I wanted. That doesn't seem fast in the world of electronics and microprocessors but at the end of the day the UP/DOWN output is controlling a mechanical device (Z axis) so it's own weight / inertia will limit it's reaction time. I hooked up the output to a terminal window and when you see the volt readings spewing on the screen at 32 times/second, and you imagine your Z axis ATTEMPTING to change direction at that rate, I don't think you need any faster.

My guess would be that the important bit would be once your system receives the THC UP or THC DOWN signal, how fast can it move. Mach is a problem there because the THC moves have no acceleration / deceleration in them so your THC RATE  setting is only a percentage of your Z rapid speed.
Keith.
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 26, 2016, 05:17:36 PM
  Mach is a problem there because the THC moves have no acceleration / deceleration in them so your THC RATE  setting is only a percentage of your Z rapid speed.
Keith.

That is interesting.
How would a stepper motor deal with that without missing steps ?

Just curious
Title: Re: Physical buttons for plasma
Post by: beefy on January 26, 2016, 05:27:23 PM
It deals with it simply be having the THC RATE set a lot lower than the rapid speed. I think my THC RATE is set at 15 percent.

A lot of people don't seem to understand that the Z axis design is also very important for faster THC speeds (with Mach3 and no accel/decel on the Z). You want as little inertia (weight) as possible so that the stepper is moving as little weight as possible. Linear bearings want to be very free moving, no stickiness. A weight counteract spring for the UP movements should help. At the end of the day you are telling the Z axis to move UP then having a change of mind and saying now go down, all as fast as possible. A heavy Z axis won't fare as well like that.

I'd hazard a guess a servo motor may help matters a little because I THINK they allow for some error from commanded movement to actual movement and will increase the current in an attempt to make the motor catch up. Not so with a stepper, try and make it do too much too quickly and it just squeals and stalls.

Keith.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 26, 2016, 06:10:51 PM
Terry, thanks for that on the RS485.  (yes its just for the torch amps and pressure, yes I'm probably being lazy as that can all be adjusted on the front panel, but you could in theory include it within the gcode as a #var for example so that if you use say the gcode files intermittently, all your settings would be there from last time).

I did suspect that the main board just interfaces with RS232 to the interface board, which has a MAX488 or MAX490 on it which provides 4 wire modbus + ground tap https://www.maximintegrated.com/en/products/interface/transceivers/MAX488.html#popuppdf



Keith,

THC.... (I know Terry pulled me up on another post a little while ago (reply 18, in my response to reply 16 here http://www.machsupport.com/forum/index.php/topic,31649.10.html) about this but I still can't get this one out of my head as potentially being a better idea.... bear with me a little before shooting me down [I couldn't keep up with the speed of responses on that one to provide a response and put forward my thoughts below]).

I've always had a problem with THC shunting the Z axis up and down and also the potential for the Z axis to stall and this obviously provides the THC limit of z axis motion.  I can appreciate what Terry said, and your post above, but as you've pointed out your maximum Z axis velocity with instant (infinite) acceleration is 15% of your potential Z axis velocity.

Below is an extract of a macropump that I set up to try to increase DRO25 which is where the THC speed parameter is held, and consider this as a simple way to increase the Z axis velocity so that if the torch is not able to accelerate fast enough upwards (after 0.1 seconds [10hz macro pump speed]), DRO 25 is increased given the velocity of the z could increase further.

As Terry said in his post, "acceleration in King".... unfortunately DRO25 is not able to make acceleration king as you only have one chunk of acceleration.... from zero to 15% of full z axis velocity in.... but after 0.1 seconds if the z is still going up.... you have no more acceleration.

say like my Z your maximum velocity is 1500mm/min (60"/min) .... not sure what everyone else is running but curious to know [my z is a 2mm pitch acme leadscrew in a delrin nut].... thinking about changing it to a 10mm pitch ballscrew.

at 20%, the maximum z axis THC velocity is 300mm/min (12"/min)..... or  5mm/sec.... say my steps / unit is 200..., that gives a pulse width per step of 1milisecond. ... so as soon as the THC receives a signal for THUP, it will step at 1kHz (5x200), and after 1 millisecond the z will be moving at 5mm/sec.... the catch is after 10 milliseconds it will still only be moving at 5mm/sec and travelled 0.5mm.

However, if we increase DRO25 to say 50% of Z axis maximum velocity for the next 10miliseconds (macropump loop), it will now be doing twice the speed after 11 milliseconds than it was doing after 10miliseconds.... hence after another 10 milliseconds it will have travelled 1.5mm .... and not just the 1mm that the z would have travelled without the "improvised acceleration curve".

Code: [Select]
THCCorrDRO = GetOEMDRO(25)
THCCorrDROOld = GetOEMDRO(1100)
THCCorrDROMin = GetOEMDRO(1101)
THCCorrDROMax = GetOEMDRO(1102)
THCCorrDROInc = GetOEMDRO(1103)

TorchEn = GetOEMLED(852)

THCEn = GetOEMLED(24)

THCLedOk = GetOEMLED(36)
THCLedUp = GetOEMLED(37)
THCLedDn = GetOEMLED(38)

Dim THCLedUpOld
Dim THCLedDnOld
Dim THCUpDn
Dim SwitchCase


' >>> add in if statement to check current THC UP & DN pins status
If THCLedUp And THCLedUpOld Then
THCUpDn = 1
ElseIf THCLedDn And THCLedDnOld Then
THCUpDn = 1
Elseif Not(THCLedUpOld) And Not(THCLedDnOld) Then
THCUpDn = 1
Elseif Not(THCLedDn) And Not(THCLedUp) Then
THCUpDn = 0
Else
THCUpDn = 0
End If


' >>> Main Loop
If isEStop() Or isStopped() Or Not(THCEn) Or Not(THCUpDn) Then
SwitchCase = 0 'set THCDRO to Min Speed Setting

' increment THCDRO up to Max Speed Setting, by increment amount.
ElseIf THCUpDn And THCCorrDRO < THCCorrDROMax Then
SwitchCase = 1

' set THCDRO to Max Speed Setting
Elseif Not(invTHCMovement) And THCCorrDRO >= THCCorrDROMax Then
SwitchCase = 2

Else
End If



Select Case SwitchCase
Case 0
SetOEMDRO(25,THCCorrDROMin)
Case 1
SetOEMDRO(25, THCCorrDRO + THCCorrDROInc)
Case 2
SetOEMDRO(25, THCCorrDROMax)
Case Else
SetOEMDRO(25,THCCorrDROMin)
End Select



' >>> Update Old Info With Current Info
THCLedUpOld = THCLedUp
THCLedDnOld = THCLedDn


 



Again, it would be interesting to know what everyone else is running z axis velocity wise (is 60"/min fast or slow?).... although with DRO25 (THC Max speed.... its obviously running slower than that, think mine stalls at about 45% so I run it at most about 30% off hand), never tested it for missed steps, although do they matter as all it is doing is tracking the Torch Voltage, so if it looses a step (or a few) it will just correct the other way and when you next touch off between cuts, the Z axis DRO is zero'd (G28.1 Z).

Thanks

Rob
Title: Re: Physical buttons for plasma
Post by: Hood on January 26, 2016, 07:04:38 PM

Again, it would be interesting to know what everyone else is running z axis velocity wise (is 60"/min fast or slow?).... although with DRO25 (THC Max speed.... its obviously running slower than that, think mine stalls at about 45% so I run it at most about 30% off hand), never tested it for missed steps, although do they matter as all it is doing is tracking the Torch Voltage, so if it looses a step (or a few) it will just correct the other way and when you next touch off between cuts, the Z axis DRO is zero'd (G28.1 Z).

Thanks

Rob

Would be interested to hear that also.
I will be using a servo on my Z and it has a rated RPM of 4000. I have several options.
Direct drive on a 10mm pitch screw thus giving 40m/min
Direct drive on 5mm screw thus giving 20m/min
4:1 gearbox with 10mm screw giving 10m/min
4:1 gearbox with 5mm screw giving 5m/min.

I was going to go for the last option as I thought 5m/min would be plenty but maybe not?

Hood
Title: Re: Physical buttons for plasma
Post by: beefy on January 26, 2016, 07:32:37 PM
Rob,

I like the concept but have no idea if it's feasible. I haven't had a great deal to do with macropumps and don't know if there is any reason it won't work. But like I said I like your way of thinking, and I'm going to keep that idea in mind.

Initially I was thinking, "Ah but my THC will run at 32 times/sec", then realised that won't matter. If the THC UP or down signal is still there after 1/10th sec, then give it some help.

I hope it works  ;D

Ah, just had a thought of a potential spanner in the works is when it stops at the higher speed. Let's say the macropump bumps the speed up then the SET VOLTS is reached, so the THC UP/DOWN signal is removed. Mach3 now will stop the Z without any deceleration, possibly causing the stepper to slip and lose it's holding torque and maybe stall. Worse case is it will stall and won't drive properly, or even when going down will keep going into the workpeice. Best case is you just lose position but the stepper keeps on doing corrections.

So this lack of acceleration may cut both ways. It limits your max instantaneous speed PLUS it MAY limit your max instantaneous stopping speed.

Something to keep in mind.

Keith.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 26, 2016, 08:03:21 PM
HI Keith , The problem with trying to lower teh amps is teh nozzles are based on teh rated current to establish a high density arc. Teh shap of teh nozzle cone and teh air pressure help to compact teh arc into a much denser arc great for cutting. When you just lower the amps the arc can get weak and lazy. High end cutter can vary teh gas % and gas pressures and modify teh charectoristics of teh current to keep a dense arc going. Low end plasma units like we use it cannot do that so you basically just end up with a weaker lazy arc. AND that is not what you really want.

IF you think about it Plasma cutting depends on a constant velocity to cut best. It is just the nature of the beast. With low end cutting the best you can do is set your anti corner dive to come in early to lock the THC down and just let it run through teh corner(slowing down naturally ) then pick back up after the corner.  Trying to manipulate all teh other variables on the fly WHEN the plasma unit was never designed to USE those variables is a beast at best and normally does NOT show an improved cut.

You would better off spending time to optimize teh Aceeleration curve of teh machine rather than relying on magic monkey dust.  

Next thing to work on is seeing IF there is an alternate cut setting that works at a lower feedspeed where your machine can better deal with corners without slowing down as much( % wise) as with high speeds.  

Then work on your tool pathing to optimize it for sharp corners.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: beefy on January 27, 2016, 12:43:51 AM
Thanks Terry,

some time ago I tried using lower amps on Finecut nozzles and the cut quality was quite bad. Maybe that was an example of what you are telling me.

Keith.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 02:42:43 AM
Love this thread, great minds at work here:)

I have spent many (too many) hours messing with cut current on my PM45 the end result is that i just leave it at 45A! It really cuts poorly at lower amps on the 45A nozzle, the 30A nozzle works best only at 30A.

I have however discovered I can drop my speed by over 1000mm/min on aluminium and still get good cuts so the window for a nice cut is quite wide it seems, this helps my machine a lot, even though I took time to design it as rigid as possible it sill wobbles on fast moves which shows in the cuts.

BTW my THC rate is 20% with a max Z of 1300mm/min
Title: Re: Physical buttons for plasma
Post by: stirling on January 27, 2016, 05:36:20 AM
Acceleration in THC controlled Z is not missing by fault, it's missing by design. Trying to put it back is missing the point.

The reason THCs have no acceleration is twofold. Firstly, if you have need or time or room to accelerate then you're already hopelessly out of position anyway so the game's already over. Secondly if you accelerate you also have to decelerate. THC MUST be able to CHANGE direction as quickly as is possible. The only way you can do that is to have NO deceleration ramp. If you have no deceleration then you CAN'T have acceleration.

Re: Speed design of Z: Let's assume your Z can move WITHOUT accel as fast as the fastest feedrate in the XY plane you'll ever need. In that case your system can follow a 45 degree slope in Z (maximum).

First question is: Do you need to be able to do this? - adjust accordingly.
Second question: Is your THC response fast enough to do this? - adjust accordingly.
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 05:55:04 AM
So Ian, what do you reckon for Z Axis speed.
Theoretically on the build I will do I could have
X and Y rapid 60m/min, whether the build will stand that at decent accel,  time will tell.
So anyway if I have these kind of X and Y rapids would it be best to get the Z as high as possible or would it not matter too much seeing as the travel on Z will be very small.

With the Z I see no problems in setting an extremely high accel with the setup I propose as there will be little mass to it and the servo should  be more than capable of handling it even direct drive.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 07:48:20 AM
I've been here before ;)

My answers were no and no :)

I think i calculated I can follow a warp of about 5-10mm across a distance of 1000mm on a good day.
Sounds bad but i don't cut corrugated and a 10mm warp is pretty bad i think, i gave up chasing some time back;)
Title: Re: Physical buttons for plasma
Post by: stirling on January 27, 2016, 08:12:51 AM
Hi Hood - Hopefully I've worded this carefully enough to avoid a good kicking from Terry  ;D - but here goes...

I kinda left it vague because it depends on what you want to do and what your THC can do. We can wax lyrical about speeds but ultimately you'll probably end up slowing Z down to match the capabilities of any (including mine) "budget" THC. Spend a few grand on one and the game changes entirely (so I'm told).

To give some perspective though, here's what the tables I've built in the past did (with my THC). I'm sure there are better (and worse) tables out there so I'm not saying this is good or bad - just what they were.

My THC samples at 1KHz. If it's set to do 1 step pulse per sample (which it is) then it can obviously drive the Z at 1000 pps. The Z was rack n pinion with a steps per of 42.44131816 steps/mm.

so Z moved at 1000 / 42.44131816 * 60 / 1000 m/min i.e. 1.4m/min.

Lets say then that it's cutting at 6m/min. It can therefore handle a slope of 6/1.4 = approx 13 degrees. I've yet to find this to be inadequate. Of course it means it couldn't cut corrugated - but it wasn't designed to - it was simply designed to cope with "typical" warpage.


With the Z I see no problems in setting an extremely high accel with the setup I propose as there will be little mass to it and the servo should  be more than capable of handling it even direct drive.

Remember with THC the Z accel is not used so it's irrelevant.
Title: Re: Physical buttons for plasma
Post by: robertspark on January 27, 2016, 08:52:40 AM
Ian, and all, thanks for taking the time to explain and cover this aspect a little more than I've read anywhere else.

...If you never get a chance to discuss your viewpoint... you never get a chance to question, consider or change it...

Like the discussion about z axis speeds, THC and plasma, I've never seen much posted on it as to what people use and although it may be viewed as boasting or something, at least it gives us an idea of how others may have done it and what they got.

I am not keen on the use of a 2mm acme thread (actually trapezoidal, but similar), but a change would require a redesign hence a pointer to speed what others use / expect is really something that someone like myself can use to value the redesign benefit from thread + delrin nut (or threaded rod + nut), to ballscrew (overkill on accuracy maybe?), rack & pinion or even belt?

Thanks for giving the insight into the 1kHz sample rate / step rate its a bit more of the chunk of infomation to consider.

Rob
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 09:39:13 AM

so Z moved at 1000 / 42.44131816 * 60 / 1000 m/min i.e. 1.4m/min.

Lets say then that it's cutting at 6m/min. It can therefore handle a slope of 6/1.4 = approx 13 degrees.


Any chance you can show the full workings of that sum please?
How you arrive at 13deg;)
Title: Re: Physical buttons for plasma
Post by: robertspark on January 27, 2016, 09:43:14 AM
the 13º is from the arctan (tan-1) of (1.4 / 6)  (opposide / adjacent)

sorry... post corrected... muppet!
Title: Re: Physical buttons for plasma
Post by: stirling on January 27, 2016, 10:24:35 AM
What he said. Sorry, was it the slope of 6/1.4 that confused? I should of course have said 1.4/6
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 10:27:56 AM
HI Ian, Sounds good to me (;-).  As to teh Z design the best solution I have seen was a very light very low inertia setup. It used linear rails and a small diam ballscrew 2TPI. The motor was as very low inertia servo drive.  IT was wickedly quick but if you turned off the machine the head would fall to the table. The frame was thin 4130 chromoly plate. It was built by one of the aircraft guys.

What always interested me was IF direct pulsing of the stepper to gain max accel and minimum time HOW is it they can do it WITH accel curve and go MUCH faster and quicker with an outside controller driving teh Z ?  

IF direct pulsing is the fastest possible way to move the motor HOW can it be done faster ???

(;-) TP
Title: Re: Physical buttons for plasma
Post by: stirling on January 27, 2016, 10:35:33 AM
What always interested me was IF direct pulsing of the stepper to gain max accel and minimum time HOW is it they can do it WITH accel curve and go MUCH faster and quicker with an outside controller driving teh Z ? 

IF direct pulsing is the fastest possible way to move the motor HOW can it be done faster ???

This sounds interesting Terry but I'm not with you. Can you run this one by me again?
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 10:51:36 AM
Robert you commented on teh lost steps. The probem with lost steps in Z is that Mach3 does not know it happened and THAT alters where it thinks Z actually is. Normall it makes it think the teh Z is HIGHER than it actually is so when the Torch head goes to cycle and the next cut it drives the torch into the metal.

NOW if teh Z motor had an encoder for position you could fix that via software and correct teh position before it caused a problem.

As to adjusting teh Torch parameters long ago I used small steppers attatached to teh Amp knob and to teh pressure regulator to adjust teh machine settings on the fly. The problem was EACH curve in teh toolpath required a different setting based on the dynamics of the curve. High end machines can calculate that on teh fly Mach3 would not stand a chance there, and did not (;-). It may be possible for Scam to do it in CaM BUT with all teh changes the Gcode would be horrible. AND you still would not get much improvent if any in cut quality.

You idea on speed changes is interesting BUT I don't think you will never get it to work at teh macropump level it s FAR to slow. You MAY be able to do it at teh Plugin level where you have access to a higher sampling rate and process speed.

But in reality what have you gained IF you never cut at Very HIGH SPEED or cut highly warped sheets .  Mosst of teh DIY tables I have seen are not rigid enough for high speed cutting. The high accel rates jerks the table around to much causing poor cut edges.

I emailed JIM as to the NEED for a different rs485 board and the first round of the conversation was all Standard HT sales GibberJab and totally talked around the need. (;-) I rephrased the question and tried again .

Worse case senario we hack into teh Motherboard and use a port sniffer to get the protocal then talk directly to it OR yous guys can develope a RTU modual to talk to it.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 11:02:43 AM
HI Ian, there are cutters on the market that use an outside THC controller that drives it OWN Z axis independant of MACH3 . They appear to be able to cut curragated sheet at high speed. To do that the Z MUST be very quick and fast obviously faster than teh normal Mach3 can do THC control.

SO is the speed limit a function of the stepper motor being directly pulsed without a curve or the speed of the THC to be able to respond.   With a fast Z 2tpi you can drive teh Z faster than the THC can keep up with corrections and get overshooting.

(;-)TP

Title: Re: Physical buttons for plasma
Post by: robertspark on January 27, 2016, 11:29:05 AM
Thanks Terry on all the previous items covered, following the thread closely.

I know mach3 is not up to the imposed acceleration, but did wonder about Mach4 as the scripts run much faster....  I'm still waiting for the new ESS plugin (no jokes please!!).

As posted previous, the Neuron THC and the CandCNC both directly control the Z axis so should be able to attain higher z axis motion with a very steep accel and deceleration, I'm also aware of another product that I'm eagerly awaiting to hit the market which will do the same.

What does everyone else do to turn THC on and off via gcode on the fly (I use sheetcam as I'm sure most probably do), before corners or small circles etc?
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 12:21:44 PM
Hi Robert , You highlighed the very question I was asking. IF teh direct pulse method(on/Off) is the faster possible move of the stepper HOW is it they can use accell and deaccel with an outside Z drive and do it faster ?? .  Maybe Scurve profile ? but that would not neccesarily be quicker for the length of the average move.

The best method would be to run teh entire THC function directly from inside of the Motion Controller itself ( ESS, UC300,etc) . Just give it the reference voltage or frequency and the Ark OK signal and it handles everything internally.  There is one that can do that currently.


Another interesting investigation is to be able to Directly TALK to the THC without a COM link to the THC. That way teh THC could be  adjusted on ANY controller ON THE FLY and without a COM link. A universal fully programmable THC without teh need to create a normal Com link to talk to it.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: stirling on January 27, 2016, 12:42:08 PM
HI Ian, there are cutters on the market that use an outside THC controller that drives it OWN Z axis independant of MACH3.

Yep.

They appear to be able to cut curragated sheet at high speed. To do that the Z MUST be very quick and fast obviously faster than teh normal Mach3 can do THC control.

Yep. Though if you look at SOME vids doing corrugated, it looks to me like they've slowed the XY feed down to match the Z rather than the other way around.

SO is the speed limit a function of the stepper motor being directly pulsed without a curve or the speed of the THC to be able to respond.

Both - one is no good without the other.

With a fast Z 2tpi you can drive teh Z faster than the THC can keep up with corrections and get overshooting.

If your Z can move faster than the THC can cope then yes - you get head bounce. That will happen whether you use Mach OR a standalone.



PS - I'd love for someone here to explain to me why they think THC with an accel ramp would be beneficial.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 12:50:43 PM

What does everyone else do to turn THC on and off via gcode on the fly (I use sheetcam as I'm sure most probably do), before corners or small circles etc?


I've been messing a lot with this stuff lately, I have the CandCNC Mp3000-DTHC2 and I use Sheetcam rules to turn the tHC on and off all over the place as I've been messing with slowing down on corners and holes etc. I'm not convinced it makes any difference yet, need to run some tests with THC on and then slow down and see if it dives or not, I don't think i have ever had a true torch-dive yet! Normal reason for a dive for me is having the volts too low, especially on the 30A consumables as there is only 1.5mm gap to play with and a volt or three out and it will dive in on the run, sometimes you can catch it and bump the volts up but usually it catches me out.

Maybe it needs a "super anti-dive" feature whereby if it senses the THC being told to go down but the volts are not changing at all i.e. the torch is running along the plate, then it blocks further drop signals, maybe even lifts a bit until it sees a volt rise - don't know if any systems offer this but it sounds useful to me ;)
Title: Re: Physical buttons for plasma
Post by: beefy on January 27, 2016, 12:54:27 PM
I'm still not convinced that ZERO acceleration is needed for THC.

There's a little goodie called deadband or hysteresis in a good THC. That acts as a buffer so if you deadband was +/- 1 volt, then so long as your accel/decel is fast enough it will at least keep the voltage within the dead band. Yeah, with accel/decel you'd pass the set point a bit BUT providing the accel/decel is fast enough it would bring the Z to a stop within the dead band.

THAT'S MY THEORY  ;D

Perhaps when Mach3 was designed the deadband factor was not part of the design, and that's the reason no accel/decel was applied to THC moves.

Fast PID control effectively has accel/decel based on error. Smaller error, then slower correction speed, bigger error, faster correction speed.

Keith.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 01:14:28 PM
HI Dave. Mach3 has anti corner dive built in. IF teh combined vel drops below the setting it locks out THCdown from working. You  still get the THC up function to prevent head collision. Most set it too low.

IF you set this too low teh head will dive due to teh THC trying to correct teh voltage as teh Vel slows down for a curve.  How far it will dive is a function of how slow teh Vel gets in that particular curve and where you have teh cutoff point set to.

Title: Re: Physical buttons for plasma
Post by: robertspark on January 27, 2016, 01:19:26 PM
Keith as you said.... why could you not use PID instead of bang bang control for THC?

(totally external to M3 or M4 of course)

That way accel and vel is proportional to the error and increased relative to the error time and decel used obviously once you get closer to the target voltage (D).... or PI control?

I guess in theory the intergral "I" part with a fast Z should be near zero?...
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 01:22:32 PM
Hi Ian, Not really, IF you try to slow down with thin sheet goods you end up blowing out the Metal and the torch shuts down (;-).  SO it has to be fairly close to cut specs to even cut.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: robertspark on January 27, 2016, 01:25:32 PM
Another interesting investigation is to be able to Directly TALK to the THC without a COM link to the THC. That way teh THC could be  adjusted on ANY controller ON THE FLY and without a COM link. A universal fully programmable THC without teh need to create a normal Com link to talk to it.

You have lost me there??

The best method would be to run teh entire THC function directly from inside of the Motion Controller itself ( ESS, UC300,etc) . Just give it the reference voltage or frequency and the Ark OK signal and it handles everything internally.  There is one that can do that currently.

can I ask which one? CISMO I thought did it and purelogic does something, but I'm not sure how much is shared from their THC to their motion controller?
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 01:30:26 PM
HI Dave. Mach3 has anti corner dive built in. IF teh combined vel drops below the setting it locks out THCdown from working. You  still get the THC up function to prevent head collision. Most set it too low.

IF you set this too low teh head will dive due to teh THC trying to correct teh voltage as teh Vel slows down for a curve.  How far it will dive is a function of how slow teh Vel gets in that particular curve and where you have teh cutoff point set to.



Thanks, i did know that but maybe i need to revisit the settings, messing with sheet cam looks good on paper but i'm not convinced it even updates theTHC in time when running unless you switch THC off way in advance which is a bit pointless.

What sort of % is recommended in the anti-dive DRO?

Also, I gather there is no existing function that addresses my suggestion of stopping downward signals IF there is no corresponding fall in volts received???
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 01:45:38 PM
HI Dave.

IF the arc volts go uP then the torch goes down

If the Arc volts go down the torch goes up

Anti corner lock blocks torch down ( Mach3 function)

Anti Gap lock blocks torch down across a void ( THC control function)

What else would you think it needs ?

I would start with the Corner lock at %90 it will vary as to your machine and it motion charectoristics

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 02:06:08 PM
Hi Hood - Hopefully I've worded this carefully enough to avoid a good kicking from Terry  ;D - but here goes...

I kinda left it vague because it depends on what you want to do and what your THC can do. We can wax lyrical about speeds but ultimately you'll probably end up slowing Z down to match the capabilities of any (including mine) "budget" THC. Spend a few grand on one and the game changes entirely (so I'm told).

To give some perspective though, here's what the tables I've built in the past did (with my THC). I'm sure there are better (and worse) tables out there so I'm not saying this is good or bad - just what they were.

My THC samples at 1KHz. If it's set to do 1 step pulse per sample (which it is) then it can obviously drive the Z at 1000 pps. The Z was rack n pinion with a steps per of 42.44131816 steps/mm.

so Z moved at 1000 / 42.44131816 * 60 / 1000 m/min i.e. 1.4m/min.

Lets say then that it's cutting at 6m/min. It can therefore handle a slope of 6/1.4 = approx 13 degrees. I've yet to find this to be inadequate. Of course it means it couldn't cut corrugated - but it wasn't designed to - it was simply designed to cope with "typical" warpage.

Thanks for that Ian, not even sure what the sample rate of the THC I have is, so looks like whichever way I go it will be plenty fast.
One thing though, I wonder if I would maybe be better trying the built in THC of the CSMIO. I am not sure how it works but if it is totally internal to the CSMIO then it should be very fast. Will have to do some reading on it.


Quote
With the Z I see no problems in setting an extremely high accel with the setup I propose as there will be little mass to it and the servo should  be more than capable of handling it even direct drive.

Remember with THC the Z accel is not used so it's irrelevant.

Yes I saw that mentioned earlier, what I was really getting at was I should be able to have a very fast acceleration with whichever scenario I choose for the motor/gearing/screw. So really there being no accel in Mach should not make a difference as the servo should be able to get to speed almost as quick as it is told to without falling foul of itself.
 For example I have a motor hooked up here, I command a RPM of 6000 at an accel of 6000 revs/s/s and it quite happily does it. There will be error of course but it still does it easily. Also there is no load so that would change things but 6000 rpm to -6000rpm at acccel of 6000rpm/s/s is fairly aggressive :D

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 03:12:40 PM
HI Dave.

IF the arc volts go uP then the torch goes down

If the Arc volts go down the torch goes up

Anti corner lock blocks torch down ( Mach3 function)

Anti Gap lock blocks torch down across a void ( THC control function)

What else would you think it needs ?

I would start with the Corner lock at %90 it will vary as to your machine and it motion charectoristics

(;-) TP

Thanks TP, most likely my misunderstanding or the mixture of terminology.
I guess Anti corner lock is the Mach3 Anti-dive??
Anti gap lock sounds like the CandCNC Tip-Saver??
I know meant-dive is not that high so i'll play with that.

I was thinking of something that would sense the fact that the THC is asking for tip down BUT the volts are NOT changing - the torch has started riding on the plate, this can happen easily on 30A consumables as there is only a 1.5mm cut height so if you were maybe 2-3 volts or so off, it would drop onto the plate and then keep trying to drop the torch until it trips a limit or the torch falls off the mount. Just wondering :)
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 03:30:06 PM
The THC cannot signal for torch down IF the voltage level has not changed. The voltage level is what drives the entire process . Mach3 has no idea what the voltage level is nor does need to know that . It simply watches the up/down signals and does what it is told to do(;-) .

Sometimes IF you get teh span volts(deadband) too wide the THC will get lazy and slow to respond . IT would be fine for thicker cuts but far too slow for thin springy sheetmetal that as you pass over a section it goes Boung  and springs straight up .500" or so. The tip will drag untill the THC can catch up.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 03:41:54 PM
Ah, but what I mean is this...

Set volts to say 90v because thats where you reckon it should be...
Start the cut and the THC reads 98v so tells Mach "Send the torch down.."
Mach drops the torch but as it so close to the surface the volts only reach say 94v,
The THC shouts "I want more, drop the torch again..."
Mach says whatever and this loop continues with the Z dropping but the volts not changing anymore because they can't.

Sounds spurious but on thin material with the 30A consumables its very easy to do.
Mach or the THC should see the repeated DOWN calls AND the fact that volts is NOT changing and say "I'm not allowing that anymore", maybe even lift the Z a mm or so. ;)
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 04:12:57 PM
(;-) Mach3 cannot read a crystal ball and figure out exacty what YOU WANTED it to do. It can ONLY do what YOU TELL  it to do .  In this case it is an operator error that no machine can compensate for as you asked it to do something that it cannot physically do. I would have simply dialed  the setvolts to teh proper voltage level as soon as I saw it lower onto teh plate after the THC delay cleared.

IF you do not correct it it will continue going DOWN until it breaks the torch, trips a limit, Goes to teh THC MIN, or breaks away teh torch(magnetic holder).

I have done all of the above as well (;-).

You do WATCH new untested programs programed with SWAG settings don't you? (;-)

(;-) TP
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 04:15:14 PM
OK That said MAYBE  ;D there is a way.  >:D

NOPE DON"T THINK SO as Mach3 has NO idea what teh arc volts really is in real time so there is nothing to compare to.

 :P TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 04:21:31 PM
OK That said MAYBE  ;D there is a way.  >:D

 :P TP

You see, thats the sort of thinking I like :)

I know it's OP error, I just put my PLC systems programming hat on for the evening - you know, the one that tells me if it CAN happen it WILL happen AND the machine should block it if possible:)

The same as pressing the "dry run"button while running code - a simple fix in the end and a button that now does nothing when it shouldn't - the BEST kind of button in my mind :)
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 04:28:50 PM
OK I don;t see HOW it could work as Mach3 has ZERO knowledge of Arc volts. It does not even know what it is. That is monitored from the THC AND the THC HAS zero KNOWLEDGE ABOUT the Z vel in Mach3.   

Nothing to compare .  Any com link between the two would be FAR too slow to react in time.

Interesting idea though, (;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 04:33:40 PM
I guess it would have to be an advanced standalone THC that drives the Z directly then, this would bring all the needed parameters under one roof;)

Ah well, it was just an idea....
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 04:36:18 PM
NOW IF you were using teh Mach3 THC plugin with a LPT  MAYBE it could work at teh plugin level as you would have knowledge of both at teh same time BUT I am not sure IF that Plugin even actually works. I don;t know of anyone that has actually even tried it to see IF it works.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 27, 2016, 04:46:34 PM
didn't know it existed :)

Personally, i think a standalone THC would likely be the best option all round, something that can devote 100% of its life to maintaining the torch height without worrying about cpu load, buffer capacity, parallel port speed and so on. :)
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 05:06:56 PM
I wonder, my THC and all other commonly used one with Mach, I would imagine just send a signal out for Up or Down. So if I were to have a Z axis on the plasma but in addition have a small servo on the torch that could raise or lower the torch via a second small slide, I could possibly control that servos drive via my THC Up/Down signals.
 In the screenshot below you can see I can configure the drive to presets, basically what that means is when a signal is seen it will do the RPM configured.
As you can see I have just entered a number of 1000rpm for Preset 1 and -1000rpm for preset 2, (Preset 0 is the default when no inputs are active, thus it is set to 0rpm) Accel and Decel can also be set there.

Will try and test this theory out in the next while but before I waste my time does anyone see anything wrong with my thoughts?

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 05:21:33 PM
Some of the THC use a pass thru Z axis signal. When NOT in thc mode it uses teh MACH3 Z axis pulses for position control BUT then in THC mode they pulse the Motor seperately Then resync back to  Mach3 Z when it is done.

YOu do have to be able to resyn to Mach3 to make SURE it knows where Z really is position wise. Otherwise CRASH.

Putting an encoder on Z ( linear or rotary) or using a servo would make that easy enough to do

(;-) TP



Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 05:36:30 PM
HIYA Hood I would get in running in a NORMAL mode first . Then when all is working well have at it.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 05:40:38 PM
Well I could probably do quite a few things to re-sync, for example I could set it up as the A axis in Mach/CSMIO and have it home to the Index pulse of the encoder. To do that all I would need to do is set the drive up so that its Primary Control method is Step/Dir and the secondary is Presets, just one input to switch between the two.

I have the ideal motor to use, it was on the X axis of the wee lathe and it could shove that along no problem so a torch and light axis would be a walk in the park for it.
Think I am going to test this out when I get a chance.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 05:41:35 PM
Ha ha TP, got to build the table yet, in fact I have to work out where I will put it and wherever that is I will have to clear a space, that will take me weeks if not months to do :D
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on January 27, 2016, 06:02:27 PM
Just looked at the servo drive I have for that wee motor, it is an Indexing drive. That means I wouldn't even have to set it up as an extra axis to home it as it is capable of homing to an index pulse itself.
It could also be set up to home to a current value thus negating the need for even a switch, just drive it to a hard stop and then have it back off a set amount, half axis travel for example.

I would imagine the Homing would only be required at the start (or end) of code as you would just use a G31 or something during the code itself, would that assumption be correct?

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 27, 2016, 10:24:19 PM
Ok I have never setup a CSMIO for plasma so I would only be guessing.  A to teh G28.1 or G31 that will depend on HOW to what to run your table.  Many use the G28.1 to reference the TOP of Material (TOM)and set it to work Zero. Others Use the G31 to reference the TOM and set work Zero.  

There are pluses and minus to each way .

You will only need one axis for Z not 2.  Just set every thing up as you would a gantry router.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 28, 2016, 03:39:27 AM
The CSMIO has a M31 macro for probing which basically is the same as G31 in Mach but all done internally in the CSMIO, if it is anything like their M84 macro it will be the dogs danglers :)

Going to test out the THC hooked up to the small servo motor/drive directly over the next wee while and see how it performs.
As said I am a while away from getting my table started so I might as well do some messing in the evenings at home to see how it performs.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 28, 2016, 06:09:59 AM
Ah, but what I mean is this...

Set volts to say 90v because thats where you reckon it should be...
Start the cut and the THC reads 98v so tells Mach "Send the torch down.."
Mach drops the torch but as it so close to the surface the volts only reach say 94v,
The THC shouts "I want more, drop the torch again..."
Mach says whatever and this loop continues with the Z dropping but the volts not changing anymore because they can't.

Sounds spurious but on thin material with the 30A consumables its very easy to do.
Mach or the THC should see the repeated DOWN calls AND the fact that volts is NOT changing and say "I'm not allowing that anymore", maybe even lift the Z a mm or so. ;)

Found it, it does exist, its in the Mp3000 settings screen and is what CandCNC calls Tip-Saver. It (should) work if you set it  to a value that keeps the torch just off the plate, so if normal volts is 90, the tip-saver is set for 2% this means once it reaches 88.2v it will stop further downward movement. Of course you have to know what value will keep the torch off the plate but it sounds good.

I have no idea what my one is set for but I know for a fact that its not as low as 2% so will be playing with that I think.
There is also max and min volts limit which i think I have set at 200 & 50 but no idea what the actual max and min cut voltages are for the PM45??
Title: Re: Physical buttons for plasma
Post by: BR549 on January 28, 2016, 07:52:23 AM
 Tip Saver and Anti Corner dive CAN be 2 different things (;-)  Tip Saver is when it crosses a void and senses a very quick change in Voltage based on time. It is controlled from teh THC side as that side sees teh voltage levels real time.

Anti corner dive is based on a change in Axis Velocity. It is normally run from teh Mach3 side as it KNOWS what the Velocities are.

You may want to read teh manual to verify that tip saver can do both.

Just a thought, (;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 28, 2016, 10:25:23 AM
I read all the manuals - CandCNC produce more manuals than a library can handle but they are very confusing at times ;)

I used google to research the Anti-Dive as I can't find it mentioned in a manual but there is plenty info out there on the 'net.

The two seem to do totally different things so running both anti-dive AND tip-saver is Ok.

I will check my settings for each one and have a play, I think tip-saver is the important one as my table does not slow much on corners unless i tell it to and thats not the same thing so i'm ok with that.
Title: Re: Physical buttons for plasma
Post by: Hood on January 28, 2016, 07:15:40 PM
Well I hooked up the small servo to its drive and set up the two inputs as Presets. Set the RPM at 4000 and -4000 at accel and decel of 4000 revs/s/s and it worked great, instant action :)

Next step is to make up a wee circuit so I can feed the Torch Up/Down outputs from the THC into the drive, can then put a voltage to the divider board and vary that slightly and see how the motor reacts to the THC signals.

Hood
Title: Re: Physical buttons for plasma
Post by: Chaoticone on January 28, 2016, 08:55:26 PM
Well I hooked up the small servo to its drive and set up the two inputs as Presets. Set the RPM at 4000 and -4000 at accel and decel of 4000 revs/s/s and it worked great, instant action :)


 :)
Title: Re: Physical buttons for plasma
Post by: stirling on January 29, 2016, 06:41:41 AM
Hi Hood - looking good. Remember what I said earlier though. It depends entirely on your THC, but I reckon you're going to end up capping that speed big time. Maybe 100 rpm or so depending on what you use for a lead.

I must have missed it somewhere but what's the idea behind having a slide on a slide for Z with an extra motor as opposed to just driving Z?

Ian
Title: Re: Physical buttons for plasma
Post by: BR549 on January 29, 2016, 09:30:45 AM
I am also watching to see where he goes with this (;-) I can think of several ways to do this BUT I want to see where Hood ends up. Might learn something new. (;-)

Unless you are doing high speed corrugated cutting a regular setup works just fine 99% of the time.

(;-) TP

Title: Re: Physical buttons for plasma
Post by: robertspark on January 29, 2016, 09:34:29 AM
I think the two z axis were to have a slower positioning axis (to touch off) and a high speed low inertia high acceleration THC axis..

Probably back on page 5... ;)
Title: Re: Physical buttons for plasma
Post by: BR549 on January 29, 2016, 11:45:24 AM
You an do that with 1 Z axis. As a plasma you do NOT need a supper heavy duty Strong torch mount as you would use with a router. You just use a very light weight low inertia Z assembly. You can Position at any speed and still have HIGH speed for the THC control.

BUT As Ian mentioned it WILL depend on teh THC being able to keep up with the Z moves. With a lot of the current THC units that use Mach3 they are slow enough that you can actually outrun teh THC and get Occilations in teh Z control from overshoot. AND that is using a small stepper setup.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: beefy on January 29, 2016, 03:02:35 PM
Talking about overshoot, that's a problem that will be made a lot worse by having any delay in the control loop.

Has anyone ever came across any tests done to measure how long it takes from Mach3 receiving a THC UP/DOWN input signal to outputting the step/direction command to the stepper drive.

I'd assume that was programmed to be as "instant" as possible.

Keith.
Title: Re: Physical buttons for plasma
Post by: Hood on January 29, 2016, 03:03:31 PM
What am I doing this for?

I suppose the initial idea was just to get the THC as responsive as possible, whether there would be any benefit  over running the THC via Mach to the CSMIO I don't know, maybe it would actually be faster doing away with the Mini THC and using the CSMIO's built in THC function. Just don't know at this stage.


I have emailed Denis to see what the response rate of the MiniTHC is, will see what the reply is, might be too slow to take any advantage that the THC direct to  servo would give (if it even would anyway :D )

Made a board up last night with a couple of optos and just hooked it up to see what it was like, seemed fine and I never even let any smoke out, so that is a bonus :)
Here is a vid of it working, obviously it doesn't show much except the servo getting to speed very quicky in either direction.

https://youtu.be/jWw6fMmjF1Q
Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on January 29, 2016, 04:26:18 PM
Keith

The THC up/down inputs I believe are sampled and processed  at Kernal speed so that part is Quick. AND yes there ARE a few advantages of using a faster kernal speed (;-)

AND I believe that your THC sample rate will determen how fast it can react to a voltage change. Too Slow and it caps teh speed of teh Z  early ??

Hood I could not see much of the motor but that is a quick set of fingers you have there.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on January 29, 2016, 05:20:36 PM
LOL TP, yes afraid it was not easy trying to turn the pot, hold the camera, hold the motor down and get the THC, pot and motor all in the same shot. At least you can see the pulley though :D

Oh and you got a good shot of the tidy section of my desk, and I am not kidding about that being the tidy section BTW :D


Hood
Title: Re: Physical buttons for plasma
Post by: beefy on January 29, 2016, 05:54:53 PM
Keith

I believe that your THC sample rate will determen how fast it can react to a voltage change. Too Slow and it caps teh speed of teh Z  early ??

(;-) TP

Electronics and computers can be super fast and assuming that is so, then the real limiting factor is mechanical, so let's have a think about this:

My theory is that the maximum USEABLE rate of a THC is completely determined by how fast a Z-axis can change direction then change back again. If you had a THC sample rate of say 50 times/sec then the worst case scenario is for 1/50 second the Z is being told to go up then for the next 1/50 second the Z is being told to go down. How many Z axis are capable of taking advantage of such demands.

I can easily bump up my sample rate to 100/sec and that's still giving me 10 milliseconds per sample to do all the calculations, compare with SET VOLTS, etc and give a THC UP/DOWN signal, certainly doable with my microcontroller.

BUT is there any benefit to reacting in 1/100th second when I can't see a Z axis being mechanically capable of taking advantage of that speed. I heard that a humming birds wings flap at about 50 times a second and when I see those little guys I can't imagine a Z axis competing with them.

And how long would be considered too long to wait for a THC UP/DOWN signal when the volts had gone outside of the SET VOLTS deadband range. My reasoning for NOT wanting to sample at such a high rate is that I can sample the voltage for longer periods and get better averaging of the noisy spiky plasma voltage.

Do you see my reasoning ?

Keith.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 29, 2016, 06:36:28 PM
YES BUT if you sample to low it effects teh quality of teh calculated values. I am SURE you are aware of the Niquest theorum and sampling rates.

The reaction time needed for THC is directly related to teh Cutting speed AND rate of change in the Material surface heights.  Cutting thin corragated sheetsgoods at high speeds can be a challange to get right.  So far as Ian once mentioned most of the cuts you see demonstarting it done are still fairly SLOW cuts. I had to go back and watch a LOT of the videos. IF you look at teh sheet it is a fairly thick gauge of metal (;-)

Yes Ian I do read your post(;-)

Just a thought, (;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 30, 2016, 04:44:19 AM
The videos on the 'tube seem to very low speed, impressive but low speed for the thickness being cut.

I was also pondering what happens to the voltage when the tip of the torch shied is about 8mm round on my PM45 and would be touching the slope of the metal - the arc will be longer as the torch can't physically get close enough, do you have to fudge the voltage and run with arc-stretch on heavily sloped metal.

Tilt the torch on the fly so its perpendicular all the time then on the up/down slopes you can vary the X/Y velocity to adjust height :)

The ultimate aim is to maintain arc length so is there a vision system that can do that? Forget trying to sample arc voltage and use a system that can look ahead and plan the move???

Too advanced??

;)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 30, 2016, 04:18:21 PM
HI Dave.

IF the arc volts go uP then the torch goes down

If the Arc volts go down the torch goes up

Anti corner lock blocks torch down ( Mach3 function)

Anti Gap lock blocks torch down across a void ( THC control function)

What else would you think it needs ?

I would start with the Corner lock at %90 it will vary as to your machine and it motion charectoristics

(;-) TP

Just a quickie...
I was fine tuning some changes to my system today and i happened to notice that Mach anti-dive wasn't even turned on, never noticed the little button and flashing yellow led before - probably been off from day one!

D'oh!
Title: Re: Physical buttons for plasma
Post by: BR549 on January 30, 2016, 04:43:07 PM
hIYA Dave you MAY want to readup about Tip Saver IF I remember back that far correctly I think it did both functions AND Tom recommended NOT to run both at teh same time.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 30, 2016, 04:51:37 PM
hmm i'll double check that, i have all the numerous candcnc manuals ;)

it read like it was ok as mach anti dive was speed related and candcnc tip saver was voltage-spike related, does the voltage rise as speed drops?

if so then i guess that may be why it was turned off, don't recall reading any warnings about it though.
Title: Re: Physical buttons for plasma
Post by: BR549 on January 30, 2016, 06:45:45 PM
IF you have the choice then run both and tune them seperately as each does do a specific job. It also may be that I remember it wrong that was a long  time ago.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on January 31, 2016, 03:52:26 AM
I asked the question on the CandCNC forum, I might get an answer one day... ;)
Title: Re: Physical buttons for plasma
Post by: robertspark on January 31, 2016, 04:15:06 AM
Thinking about designing a better plasma z axis...


Anybody used anything like this for a z axis leadscrew?

High helix leadscrew, 10mm dia, 12mm lead, with a delrin nut (22mm of)

http://www.igus.co.uk/wpck/7001/DryLin_Steilgewindemuttern

Was looking at 1610 or 1616 ballscrew as a faster response zaxis for a plasma as well.

Why the 10mm leadscrew you may ask, smaller, lighter, easier to couple, no need to have ends machined for bearings or couplings, especially when I would be only after a short length (150mm)

Open to comment, thanks

Edit, drive by stepper, with programmable digital drive, hence choice of microstep resolution.
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 31, 2016, 08:17:03 AM
Thinking about designing a better plasma z axis...


Anybody used anything like this for a z axis leadscrew?

 
Open to comment, thanks

Edit, drive by stepper, with programmable digital drive, hence choice of microstep resolution.

Hi Robert,
  I picked some of these up some time ago (when they were cheap  :) ) to use in a p&p gantry robot.

Teflon coated steel screw, Delrin ? Acetal ? zero backlash nut (self compensating).
KERK ... I think.
3/8" +/- OD x 1/5" +/- lead. VERY slick.

I will contribute to the discussion by donating one of these to you If you'd like.
Guess it depends where in the world you are to be practical as far as shipping goes.

Kind regards,
Russ
Title: Re: Physical buttons for plasma
Post by: robertspark on January 31, 2016, 09:08:36 AM
Thanks Russ for the offer, much appreciated.

1/5" lead is about a 5mm pitch, and 5/8 is about 16mm dia... So unless I got it wrong they are approximately eqivelent to a 1605 ballscrew although using delrin/acetal etc nut.

I'm presently running a 2mm pitch 10mm trapezoidal leadscrew.

I'm in the UK and may take you up on the offer if it's still available after a bit more advice on leadscrew + plasma + z axis.
Title: Re: Physical buttons for plasma
Post by: Overloaded on January 31, 2016, 09:28:50 AM
Oooops, my mistake.
I crossed 1/2 " with .5"

They are about one half inch lead.

  ..... and 3/8" diameter, not 5/8".

Russ
 :)
Title: Re: Physical buttons for plasma
Post by: BR549 on January 31, 2016, 02:37:07 PM
For a direct drive stepper you need between  2-5 tpi on the feed screw.  AND always keep this in mind That screw will be in the NASTIEST, abrasive place you can ever place a screw in period, bar none.  Either count on replacing it often or use bellows to protect the screw and nut.

Play on the screw will drive your THC nuts and give terrible cuts.

You only need about 6" of travel max.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on February 02, 2016, 03:09:02 PM
Just got a reply from Denis (MiniTHC guy) regarding the frequency of the THC, not had time to really study yet but looks like he is talking about 20KHz if my quick calcs are right.
Anyway here it is.



Sorry for delayed reply.
I had to talk to the engineers to ask your question.

Internal feedback loop is about 0.05-0.06 milliseconds (0.00005 s).
(Oscillator clock is 8MHz, and ADC accumulates about 400 values in row, to apply the filter. So 1/(8E6 Hz) * 400 = 0.05 ms)

If you connecting THC to computer, response time (with LPT) will be anyway greater, due to signal need to be transferred to computer and back to motor, which is 1/25000 * 2 = 0.08 milliseconds.

25 kHz seems to be enough to respond even for curve sheets.
For example, with max possible cutting speed (10 m/min), machine travels 170 mm/sec.
That mean, for every 1 mm, Mach3 is able to receive 75 signals up/down



Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on February 02, 2016, 04:51:25 PM
Have they ever said if they use a spanvolts (deadband ) or PID control for the thc ?  The numbers look very good to me . BUT I am not sure that Mach3 can keep up that fast but it is better to be quicker than slower in this case.

Thanks for the Numbers Hood, Those are VERY hard to come by (;-)

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on February 02, 2016, 05:47:17 PM
No TP they never said but then again I never asked.
I presume that is what the 400 samples bit is, ie they take 400 samples before they issue an up/down command. How they sort these samples I have no idea.

There was another part to the email that talked about PID but that was in relation to driving the motor directly from the THC, I presume without a servo drive. I had mentioned I was thinking of driving the motor independent of Mach and I presume they were thinking DC motor.

Anyway here is that part.

As far as I can tell, there is two ways to implement direct motor control:
H-bridge and PID controller (like the servo motor drivers).
I can't say if you really want to implement your own PID, but we tried both ways, and I will be happy to share its pros and cons.


If I do decide to drive the motor direct from the THC it will be via the Preset Inputs on the servo drive so that doesnt really matter to me.

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on February 02, 2016, 06:51:41 PM
IT sure would be nice to hear their comments on both methods (;-).

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on February 03, 2016, 06:04:27 PM
Sorry for this being a very long post but wondering what the experienced plasma guys thoughts are, thats you TP, Ian, Rob, Dave and any others ;)

 I have been messing around with the servo drive to see what my options would be.
So here are a few things you can do in this drive.
You can have 2 modes of operation, so for example you could have :-

1. The main mode as  Step/Dir then the override mode as Preset Velocity (RPM) .
2. The main mode as Preset Velocity then the override mode as Preset Position (encoder counts)

You can also set up an input to start the motor homing and you can have various methods of defining home. One option is a switch, another is motor current value etc etc.
Also for the Homing you can set a back off amount if desired, that would mean when the home sensor is seen it will back off a desired amount and then set the encoder count in the drive zero.

Another nice feature is you can define an input to have multiple meanings, for example I have set one up as Operation mode override and also Preset Position 0, another I have set up as Operation mode override and preset position 2.


Now that I have mentioned some of the options I have in the drive here are a couple of ways I could work this axis.

1. I could use Step/Dir as one mode and Preset Velocity as the second. I could then command the drive as the Z axis from Mach then when I want THC to take over I just use the override input and either up or down and these would get operated directly from the THC.
2. I could use Preset Velocity for one mode and Preset Position for the other and that would mean I do not use the Z Axis at all in Mach.
3. Just have Mach control the whole lot and have the THC control the axis via Machs UP/Dn commands

So in example 1. above what would happen is I command a home move, the axis would move to the surface (under the drives control) reach the current value then tell Mach it has homed and Mach  would set the Z Axis as zero. Mach would then back off to pierce height and XY move to position and the torch would start, after the defined time then Mach would lower to the cut height and then pass control over to the THC and the THC would control the servo directly via the Preset Velocity inputs. Once that part of the cut was complete the THC would hand back to Mach, Mach would move to safe Z, move XY then tell the drive to home and the cycle would repeat.


In example 2 above the Z axis would not be controlled from Mach at all. A signal to home, probably from a M Code, would be sent to the drive, drive would move the motor down until it touched the material and the motors current reached the set amount. It would then back off the preset amount, call this safe Z, then Mach would be told it can continue.
Next X Y would move and then  the Mode Override/Preset Position Input would send the axis to the pierce height, once pierce time is elapsed the next Input would be used to move to cut height and then control of the drive would be handed to the THC  by using the Preset Velocity Inputs for Up/Down. Once cut is complete the axis would be sent back to the safe Z height and then the operation would repeat for the next cut.


I can see both 1 and 2 working and the second method would be more configurable with respect to accell and decel, as they can be set individually in the drive, but I can see that the pierce height and cut height would be fixed values in the drive. That could be overcome by having more than 1 input for  pierce heights and thus I could have 2 or 3 different pierce heights. I think the cut height is normally a fixed height (1.5mm or so) after which the THC will take over and vary accordingly.

What do people think?
Any pitfalls that can be seen in any of the options?
Is this worth pursuing or am I better just letting Mach handle the whole thing?
 The advantage I see with the THC controlling the drive direct is it cuts out the middle man (Machs Up/Dn), so it should be more responsive, but would it make much difference?

At the moment I am thinking Option 1 would be the best but.....

Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on February 03, 2016, 07:33:26 PM
I would hook it up as a normal Mach3 thc setup , USE it for a while . I would bet you will not have any problems cutting what you cut.  I do it about every day with a slow stepper setup (;-).

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on February 03, 2016, 07:56:32 PM
Och man, that is just boring :D

Ok I can probably do that but I think I will use the AB drive rather than the Samsung I originally intended, just in case :)

Also I reckon the drive homing would be a good way to touch off, so I could use that part. It would allow me to have the Z Axis as a rigid light set-up and not have to have a floating torch.

I home the Beaver Mill with the servo drives except I have it configured for Switch and Index pulse. I also home the lathes turret via the AB drive, on that I use the motor current method, they both work great and I can see it working equally well on the plasma.

The only concern I do have with driving the UP/DN via Mach is I will be using the CSMIO, there may be more of a delay there than would otherwise be if using the PP.
The inbuilt THC in the CSMIO would probably be faster but I suppose time will tell.

If I can wire/configure the panel up so  that I can easily swap to different options that may be the best way.

The only problem I see with using the AB drive for Z is the motor is small, only 50W but if I put it through the 4:1 gearbox and keep the Z light I think it should be enough.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 03, 2016, 08:00:35 PM
Hood, thanks for the too highly rated complement, I'm really just starting out on a very long journey.

I know zero about servo drives, that being said, I like your options, they look very interesting and may have advantages of driving the THC directly.

However... If you drive the THC directly, the z axis DRO will have zero idea where the torch actually is until the next touch off (g28.1).... I don't think this would be a problem with my setup, as I touch off before my torch refires every time.

Another problem you may have if you control the servo directly via the THC.... You won't be able to turn the THC off when blended tradjectory is below x% of the feedrate....

With regards to the rest of the control, I'll try to explain my setup (right, wrong,  works for me).  I use sheetcam, and that goes care of my touch off (I use g28.1, but you can use g31), and also via snipetts, I turn my THC on and off for small circles and corners etc.

Really, consider my setup a little further, I use an ESS, and turn my THC on and off by making and breaking the THCOK signal back from my THC, given THCUp and THCDn are ignored when THCOK is not present.

The THCOK signal is broken by feeding the THCOK feed via a relay which is controlled via m10px and m11px as these are the only mcodes that don't cause a divot and tradjectory to slow for the mcode execution.

The THC is a proma (actually its Dave's old one...) (I am awaiting a new product on the market, .... Since last sept..!!, hence I nearly built my own and have a few times nearly bought the  neuron... If they dropped the pricing back to their introductory price I'd be there like a shot!). I have wasted a great deal of time exploring everyone THC that I could find on the market to try to understand what each offered.

Hence its crude (only settings are hysterysis, torch transfer voltage and target voltage), and its slow... It uses good old fashioned relays... Optoisolators would have been way faster....I would not recommend them, although for the cost it has met its needs as a very entry level thc. (Read:cheap!)

Anyway, the THC is set with a very close hysterysis (2v, the minimum), and an arc transfer voltage of only 5 volts above my target.... The reason behind this is because its acting as an anti-dive function.... Hence the THCOK signal will drop out (or not be enabled until the torch voltage is within 5v of the target voltage, and any spikes the THCOK signal will drop out.   From all the info I've found on the net, 1torch volt is about 0.32 to 0.64mm of torch height... Say 0.5mm per volt.... Hence 2v will be around 1mm of cut height (+/- ~ 0.3 mm).

I leave the THC to control the torch height.

I leave sheetcam to insert my code snippets (which I may hand adjust onscreen) to turn my THC on and off via m10px and m11px, via the post processor.

I leave sheetcam to inset my pierce pause by setting up the relevant tool settings  (pierce delay, pierce height, initial cut height and do my touch off before every pierce)

Code snippets in sheetcam reduce my feedrate for circular cuts to 60% of the straight line feedrate automatically also for circles less than 1.5" dia (most of my metal is under 4mm)

Hope some of that is for use to someone

Rob
Title: Re: Physical buttons for plasma
Post by: BR549 on February 03, 2016, 09:11:13 PM
OH boy Hood are you in for an edumacation. With plasma you HOME z to find teh top of the material not to establish a real Z home. There are 3 main sensing methods ohmic tip, Remote offset switch, and floating Switch on Z. AND 2 possiblities of motion with each, G28.1 and G31

Now that is with the standard Mach3 methods. THere are actually many more but that is another story.

 8) TP

Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 01:05:30 AM
Oh... I use floating switch...

Have a look at this table, you can use bits of the idea too.

http://m.instructables.com/id/CNC-Plasma-Table/

Rob
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 02:32:29 AM
Whatever you use, i would not use motor current sensing for the IHS method, unless you cut 12mm plate all day it will buckle the sheet and give bad readings for z-zero. Since tweaking my system up with an offset switch probe and increased z motor tuning, the cuts have certainly improved and I am fairly confident it can follow pretty much any warp I will see.

I still have the floating z setup, connected to my limits chain, i would not build without  this as its a good safety feature in case of a dive, a mag-break torch holder would probably be a good replacement though, i will be wiring my z limit to the e-stop circuit soon as the limits are ignored when doing a g28.1 and if my probe switch fails it will plant the torch heavily into the sheet, there is enough torque in my stepper/screw drive that it will not stall the motor and just keeps on going! The failure point is that it rips the delrin nut out of the z-axis body which means stripping it down to replace it.

I admire your work on this though, I love R&D work, used to de plenty of it once in the day-job, only used servo's once though and that was step/direction to the servo drive and then closed-loop with encoder/resolver on the servo motor, this was a feed system for a stamping machine.

Proma did have an upgrade version of their THC and it took over direct control of the Z motor, switching back to Mach when stopped, I nearly tried it but splurged on the MP3000 instead. I managed to get the loop response times from Proma guy and it was certainly slow, ok for cutting thick stuff but I found it failed on thin sheet due to the speed needed.
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 03:07:45 AM
Hood, thanks for the too highly rated complement, I'm really just starting out on a very long journey.
You know way more than me on the subject, so that is reason enough to ask your advice ;)


Quote
I know zero about servo drives, that being said, I like your options, they look very interesting and may have advantages of driving the THC directly.

However... If you drive the THC directly, the z axis DRO will have zero idea where the torch actually is until the next touch off (g28.1).... I don't think this would be a problem with my setup, as I touch off before my torch refires every time.
Don't think that would be an issue as I too would be touching off each new cut

Quote
Another problem you may have if you control the servo directly via the THC.... You won't be able to turn the THC off when blended tradjectory is below x% of the feedrate....

Not too sure about this, the THC has an input that locks it out, so I could likely use that. Not sure however in what circumstances it would really be needed, there should be very little slowdown at corners, then again maybe it doesn't take much. With servos I will have high acceleration (hopefully ;) ) and the code will hopefully be such that even a sharp corner the cut will roll round the corner at the radius of the kerf thus never actually having to come to a stop. Maybe I will end up with a slowdown but if that is the case then I can probably integrate the Lock function.
The THC itself has Anti-Dive in it but how well it works I don't know.

Quote
With regards to the rest of the control, I'll try to explain my setup (right, wrong,  works for me).  I use sheetcam, and that goes care of my touch off (I use g28.1, but you can use g31), and also via snipetts, I turn my THC on and off for small circles and corners etc.

Really, consider my setup a little further, I use an ESS, and turn my THC on and off by making and breaking the THCOK signal back from my THC, given THCUp and THCDn are ignored when THCOK is not present.

The THCOK signal is broken by feeding the THCOK feed via a relay which is controlled via m10px and m11px as these are the only mcodes that don't cause a divot and tradjectory to slow for the mcode execution.

The THC is a proma (actually its Dave's old one...) (I am awaiting a new product on the market, .... Since last sept..!!, hence I nearly built my own and have a few times nearly bought the  neuron... If they dropped the pricing back to their introductory price I'd be there like a shot!). I have wasted a great deal of time exploring everyone THC that I could find on the market to try to understand what each offered.

Hence its crude (only settings are hysterysis, torch transfer voltage and target voltage), and its slow... It uses good old fashioned relays... Optoisolators would have been way faster....I would not recommend them, although for the cost it has met its needs as a very entry level thc. (Read:cheap!)

Anyway, the THC is set with a very close hysterysis (2v, the minimum), and an arc transfer voltage of only 5 volts above my target.... The reason behind this is because its acting as an anti-dive function.... Hence the THCOK signal will drop out (or not be enabled until the torch voltage is within 5v of the target voltage, and any spikes the THCOK signal will drop out.   From all the info I've found on the net, 1torch volt is about 0.32 to 0.64mm of torch height... Say 0.5mm per volt.... Hence 2v will be around 1mm of cut height (+/- ~ 0.3 mm).

I leave the THC to control the torch height.

I leave sheetcam to insert my code snippets (which I may hand adjust onscreen) to turn my THC on and off via m10px and m11px, via the post processor.

I leave sheetcam to inset my pierce pause by setting up the relevant tool settings  (pierce delay, pierce height, initial cut height and do my touch off before every pierce)

Code snippets in sheetcam reduce my feedrate for circular cuts to 60% of the straight line feedrate automatically also for circles less than 1.5" dia (most of my metal is under 4mm)

Hope some of that is for use to someone

Rob

Thanks for the insight, time will tell how my THC works, looks decent on paper but what it will be like in real life is another matter.
I will likely just use BobCAD for the code as I already have it, how good it is for Plasma I have no idea but the PP are quite easy to alter to suit so I should manage to customise it if I find it is not suitable from the start.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 03:09:03 AM
Yup the Proma is a bad choice... but it was "cost effective" and a starting point on a long learning road ("if I knew then what I know now...")

Basically anything that relies on relays is a bad idea for THC for a start!

the Proma "SD" being direct drive [pass through until Torch Voltage Sensed, then Proma Controlled until the end of the cut) is just an improvement by way of some motion controllers not having THC programmed into them (Chinese USB ones or the USB-SS for instance [started there!, read line 1 above]).... but still uses relays it "looks" like.... (if you read the manual closely).

The SD does not offer the THC Inhibit if blended trajectory drops below "x%" of the feedrate...

And it also does not offer M-code inhibit for corners to turn the THC on & off...
http://www.planet-cnc.com/faq/THC/THCSD.png

If it detects torch voltage.... it controls !




Ohmic has always interested me.... but if you have a working floating head.... is it a gimic or does it really improve the cut?   
All depends I guess on what you are cutting (thickness, surface rust / coating etc) and how you are cutting it (water table).

Could also be considered a "double tap".

I did not know G28.1 ignores limits....   what about if you tie your home and limit inputs together using the same pin numbers?

And put the floating head (or ohmic) on the "probe" input (which is my arrangement)?

Rob
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 03:11:35 AM
OH boy Hood are you in for an edumacation. With plasma you HOME z to find teh top of the material not to establish a real Z home. There are 3 main sensing methods ohmic tip, Remote offset switch, and floating Switch on Z. AND 2 possiblities of motion with each, G28.1 and G31

Now that is with the standard Mach3 methods. THere are actually many more but that is another story.

 8) TP



I will be homing to the surface or rather I will be touching off the surface, whether I use that as the Home or use  G31 (M31) and have a separate home switch for fully up I am not sure at this time.
I was thinking of having Index homing on full retract, or close to it, and then using the drives homing to touch off the material by using the M31 macro.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 03:12:20 AM
Oh... I use floating switch...

Have a look at this table, you can use bits of the idea too.

http://m.instructables.com/id/CNC-Plasma-Table/

Rob

Thanks Rob, will have a look in a bit :)
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 03:27:56 AM
Whatever you use, i would not use motor current sensing for the IHS method, unless you cut 12mm plate all day it will buckle the sheet and give bad readings for z-zero. Since tweaking my system up with an offset switch probe and increased z motor tuning, the cuts have certainly improved and I am fairly confident it can follow pretty much any warp I will see.

The current sensing method can be set to any value so can be extremely sensitive, it can be that sensitive that it is set too low and the motor doesnt even move :D
As an example doing the testing last night I had it set to 0.5 amps and it just took a push against the end of the pulley for it to stop, I set it to 0.1amps and it wouldn't move, it just set home where it was. So next I tried 0.3 and it just needed the slightest touch to stop it. Obviously once there is the weight of the axis and the torch I will need to find the current required for the perfect touch off but it is as easy as changing a number on the computer screen and activating the home input to test.
 Mostly I will be doing 4mm upwards and the least I am likely to cut is 1.5mm so hopefully I can set the current value in the drive so as it only needs to tickle the material :)

Quote
I still have the floating z setup, connected to my limits chain, i would not build without  this as its a good safety feature in case of a dive, a mag-break torch holder would probably be a good replacement though, i will be wiring my z limit to the e-stop circuit soon as the limits are ignored when doing a g28.1 and if my probe switch fails it will plant the torch heavily into the sheet, there is enough torque in my stepper/screw drive that it will not stall the motor and just keeps on going! The failure point is that it rips the delrin nut out of the z-axis body which means stripping it down to replace it.
I was thinking about having the magnetic style break away torch holder, purchased a couple of 2mm sensing Prox's for this, intending to wire them into an E-Stop chain. If the torch hits something, as I am sure it will, especially at the start of my plasma escapades, then the machine will stop and hopefully nothing will be damaged ::)


Quote
I admire your work on this though, I love R&D work, used to de plenty of it once in the day-job, only used servo's once though and that was step/direction to the servo drive and then closed-loop with encoder/resolver on the servo motor, this was a feed system for a stamping machine.

This will be a Step/Dir setup as although I think the CSMIO/IP-A is the best controller I have used so far with Mach, I have a CSMIO-IP-S pulled from the wee lathe, so will be using it

Quote
Proma did have an upgrade version of their THC and it took over direct control of the Z motor, switching back to Mach when stopped, I nearly tried it but splurged on the MP3000 instead. I managed to get the loop response times from Proma guy and it was certainly slow, ok for cutting thick stuff but I found it failed on thin sheet due to the speed needed.

From the info I got from Denis it seems the response time of the MiniTHC is fast, what it will be like in real life is another matter but I will soon find out. If I find I don't like it I can always try the software THC that the CSMIO has inbuilt.
Title: Re: Physical buttons for plasma
Post by: stirling on February 04, 2016, 06:43:58 AM
Hood - Seems you have the following basic options:

1) MiniTHC driving CSMIO firmware THC functionality.

Arguably the easiest to set up and use because it *should* work out-of-the-box.

2) CSMIO Analog driving plugin THC functionality.

I don't really follow CS Labs description of how this ties together.

3) MiniTHC driving your "smart servo".

From your proposals, This looks like it *should* work. The "thing" about this method of course is that you're effectively converting your MiniTHC into a standalone. Not sure how you'd do anti-dive but (as you've indicated) with properly good accel it's less of an issue anyway.

My money would be 1,3 for a quick win and 3,1 for the fun of it.
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 07:18:10 AM
may be of interest of someone:

http://www.metalwebnews.com/howto/plasma/presentation.pdf
Title: Re: Physical buttons for plasma
Post by: stirling on February 04, 2016, 08:32:47 AM
Is this worth pursuing or am I better just letting Mach handle the whole thing?
 The advantage I see with the THC controlling the drive direct is it cuts out the middle man (Machs Up/Dn), so it should be more responsive, but would it make much difference?

Not sure if this is a slip of the tongue key, but of course Mach3 per se is going to have nothing to do with up/down. That's going to be done by your CSMIO. So the question would then become - does the "smart" servo react any faster or slower vs the CSMIO to any degree that makes a difference? remember it's not as simple as which one's faster. Fast is good but too fast is no good at all.
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 09:58:06 AM
OK there are good things about a fast thc and bad things about a fast thc.

A fast THC makes it much more sensitive to things like corner dive, gap dive. With a fast thc you may find yourself having to set these features based on Plate thickness. What works well with thin sheetgoods may not work well with heavy plate.

DOes the CSMIO do anti corner dive based on Mach3 settings ?  Like Mach3 would do. Does the THC do anti gap dive ?? how adjustable is it ?? Does it have a spanvolt(deadband) setting ?  Can you adjust these from on screen ??

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 11:26:32 AM
From your proposals, This looks like it *should* work. The "thing" about this method of course is that you're effectively converting your MiniTHC into a standalone. Not sure how you'd do anti-dive but (as you've indicated) with properly good accel it's less of an issue anyway.

The THC has an inbuilt Antidive, I will post the info from the manual in another post.
I am sorely tempted to try the stand alone option but probably better just starting with the basic like TP says and have the option of easy swap wired into the panel so I can test the other options when time permits.

Is this worth pursuing or am I better just letting Mach handle the whole thing?
 The advantage I see with the THC controlling the drive direct is it cuts out the middle man (Machs Up/Dn), so it should be more responsive, but would it make much difference?

Not sure if this is a slip of the tongue key, but of course Mach3 per se is going to have nothing to do with up/down. That's going to be done by your CSMIO. So the question would then become - does the "smart" servo react any faster or slower vs the CSMIO to any degree that makes a difference? remember it's not as simple as which one's faster. Fast is good but too fast is no good at all.

Well it wasn't really as I am not sure how things will work. The CSMIO has its own built in software THC which should be fast but if I use the MiniTHC via the CSMIO hardware to Mach, then it introduces another delay. I don't really know how that would behave. Rob said he uses the ESS and it seems to work ok, so I would imagine the delays would be similar with the CSMIO.

OK there are good things about a fast thc and bad things about a fast thc.

A fast THC makes it much more sensitive to things like corner dive, gap dive. With a fast thc you may find yourself having to set these features based on Plate thickness. What works well with thin sheetgoods may not work well with heavy plate.

DOes the CSMIO do anti corner dive based on Mach3 settings ?  Like Mach3 would do. Does the THC do anti gap dive ?? how adjustable is it ?? Does it have a spanvolt(deadband) setting ?  Can you adjust these from on screen ??

(;-) TP

I believe whether using the inbuilt software THC in the CSMIO or just using an external one via the CSMIO then it all goes via Mach and has the same functions. That is only what I understand though, it may not be the case as I do not personally know anyone using the CSMIO for Plasma.
The MiniTHC has inbuilt Antidive and it is adjustable on the THC itself, push the knob to select the AntiDive page and turn the knob to select the sensitivity you want. Again how well it works onl;y time will tell. Details from the MiniTHC manual will be posyted in the next post.
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 11:32:06 AM
Ok I have just copied the relevant parts from the manual regarding the AnyiDive, it is attached below.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on February 04, 2016, 11:41:04 AM
Well it wasn't really as I am not sure how things will work. The CSMIO has its own built in software THC which should be fast but if I use the MiniTHC via the CSMIO hardware to Mach, then it introduces another delay. I don't really know how that would behave. Rob said he uses the ESS and it seems to work ok, so I would imagine the delays would be similar with the CSMIO.

I think you're maybe getting the wrong end of the stick here. THC functionality is in the controller. i.e. it's in the Parallel Port Driver OR it has to be in the external controller - Mach "proper" only controls the interface.
Title: Re: Physical buttons for plasma
Post by: stirling on February 04, 2016, 11:45:15 AM
Ah OK - that is NOT anti-corner-dive, that's kerf crossing.

EDIT: I thought it was a bit strange when you said it did anti-dive. That's usually (always?) done in the controller because it knows about feedrate. Kerf crossing is done (as it is here) in the THC because IT knows about "out of character" voltage changes.
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 11:58:08 AM
Ok I presumed the UP/Dn commands were actually Mach telling the plugin but if it is totally internal to the plugin and it is the plugin that updates Mach then that is good :) Should make things faster than I was envisaging.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 12:04:17 PM
Which plugin?    ...confused....

Thought the discussion was regarding the minithc from po-mo...

And the option of controlling a servo directly (up/dn) or back to the cismo .... Which will output step and direct to the servo... Kind of forwarding the THCUp or THCDn provided the THCOK is also present.
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 12:07:29 PM
I call that anti gap dive and yes it HAS to be controlled at teh THC level as it kows what teh voltage levels are.  Anti corner dive is a setting controlled from Mach3 BUT in the case of an outside controller the controller has to actually monitor teh process(Mix Vel) and restrict ONLY THCdown not up.

It is always much better IF you can controll all teh THC functions from Mach3 instead of manually setting teh THC values.  This makes it easy to base you cutting parameters based on material cut.

You can use Mach3 tool table to store and update values at program load . Then in your Cam you base your materials on tool# THAT works very well.

And that brings up CAM. I normally use SheetCam as it has been developed with plasma in mind not as an after thought.  Very adaptable to ANY plasma needs.

(;-) TP

Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 12:16:12 PM
Which plugin?    ...confused....

Thought the discussion was regarding the minithc from po-mo...

And the option of controlling a servo directly (up/dn) or back to the cismo .... Which will output step and direct to the servo... Kind of forwarding the THCUp or THCDn provided the THCOK is also present.

I was talking about the CSMIO plugin as that is what I will be using as the motion controller.
Whether I end up making the Z totally stand alone (unlikely at this stage) or via Mach/CSMIO/MiniTHC (most likely) I am not sure.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 12:17:13 PM
Anti corner dive is a setting controlled from Mach3

Is that a simple ON/OFF signal?

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 12:18:03 PM
The latter is the bog standard
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 12:20:31 PM
The actual THC up/down with an outside controller is controlled at teh Controller itself NOT mach3  > IF you tried to let Mach3 do it it would be MUCH too slow.

NOW a GOOD THC controller has a screen interface that allows teh OP to setup teh THC control parameters ON SCREEN.

In the case of the CSMIO "IF" the internal controls of the THC are  done correctly it would be perfect.  
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 12:21:53 PM
Yes I know but I will most likely do the TouchOff external to Mach and use the drives Homing procedure.
Through time I will likely experiment and maybe have Mach control the Z and THC control the UP/Dn externally or maybe even go the whole hog and have the THC and Servo drive totally control the Z Axis.

Hood

Edit, this reply was to Rob, should have quoted ::)
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 12:23:57 PM
The actual THC up/down with an outside controller is controlled at teh Controller itself NOT mach3  > IF you tried to let Mach3 do it it would be MUCH too slow.

NOW a GOOD THC controller has a screen interface that allows teh OP to setup teh THC control parameters ON SCREEN.

In the case of the CSMIO "IF" the internal controls of the THC are  done correctly it would be perfect.   
The Mini THC has a screen that you can alter voltage, delay and AntiDive, again how it performs in real life only time will tell.
Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 12:24:57 PM
ANti corner dive in Mach3 has an On/OFF control AND you can set teh level at which it kicks in as a percent of feedrate. IF you set teh level at 80% then when teh Combined Vel in Mach3 slows to a level of 80% of teh called feedrate it should LOCK out the thcdown motion. When the Comb Vel gets back above 80% it releases teh lockout and THCdown can work again.

Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 12:27:10 PM
ANti corner dive in Mach3 has an On/OFF control AND you can set teh level at which it kicks in as a percent of feedrate. IF you set teh level at 80% then when teh Combined Vel in Mach3 slows to a level of 80% of teh called feedrate it should LOCK out the thcdown motion. When the Comb Vel gets back above 80% it releases teh lockout and THCdown can work again.



Ok that is fine, the MiniTHC has an input to lock the THC, so that could easily be connected via the AntiCorner Dive I think :)
Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 12:48:37 PM
ANti corner dive in Mach3 has an On/OFF control AND you can set teh level at which it kicks in as a percent of feedrate. IF you set teh level at 80% then when teh Combined Vel in Mach3 slows to a level of 80% of teh called feedrate it should LOCK out the thcdown motion. When the Comb Vel gets back above 80% it releases teh lockout and THCdown can work again.



Ok that is fine, the MiniTHC has an input to lock the THC, so that could easily be connected via the AntiCorner Dive I think :)
Hood

But I don't think you can programme an anti-dive output within Mach can you.... It's all an internal fiction that a plugin can tap into is it not.

If anti-dive can be tied to an output ...here to learn please....


Guess it could be via macropump or brains.... But is that not too slow, hence you want it controlled in the motion controller via mach3 40hz fast loop?

Given if you were cutting a square say, the blended velocity will change maybe below the 80% feedrate at the corners or if you use fishtails (or whatever the correct term is)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 12:51:38 PM
Now, if you could come up with a device that eliminated start and end divots, I would buy it ;)

These are by far the most annoying part of plasma for me, seems whatever i try, and i have tried hundreds of combinations, nothing seems to get rid of them, plus it seems you need different settings for inside and outside starts/ends - total PITA :)


I have my Mach Anti-dive set at 95% and the CandCNC Tip-saver set at 2% they seem to play well together, still not got a reply on the CandCNC forum D'0h!
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 12:53:20 PM
Dave how are you controlling THC?

Is it via mcode?.... Or what?
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 12:58:56 PM
Dave,

Divot at the end, you could try using m10px and m11px to turn your torch on and off, and change your post processor to extend your torch travel a little.... So the machine motion does not slow down before the torch goes off.


Divot at the start.... Sorry you are stuck there unless you can pierce in the waste (hole centre, out of the part or art in your case.... Nice website must say)

Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 01:02:57 PM
Dave how are you controlling THC?

Is it via mcode?.... Or what?

Hi

Yes, sort of.

Its a CandCNC MP3000-DTHC2 so has the ability to set THC via the CAM, I set everything in SheetCam - Volts, Pierce delay, THC on/off, THC delay etc.

I use Sheetcam rules to turn the THC on/off on corners but since setting my anti-dive and tip-saver i might stop this and see what happens.

The MP3000 has its own cpu and talks to Mach via the serial port, when you load a code file the settings are sent through to the THC and stored there.

I use the M10p/M11p (?) codes to turn the torch on and off and none of the THC commands cause any pauses in motion.
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 01:10:02 PM
Have you looked at the sheetcam post processor and had a go at tweaking the m11p and m10p (10=off, 11=on)... As they only function if a motion movement is present (g01 for example) so most people use a phantom axis... You could change this to a real movement to extent the last movement by say 20mm (or something that works), so the machine does not slow down the feedrate to zero and then turn the torch off
Title: Re: Physical buttons for plasma
Post by: stirling on February 04, 2016, 01:13:42 PM
ANti corner dive in Mach3 has an On/OFF control AND you can set teh level at which it kicks in as a percent of feedrate. IF you set teh level at 80% then when teh Combined Vel in Mach3 slows to a level of 80% of teh called feedrate it should LOCK out the thcdown motion. When the Comb Vel gets back above 80% it releases teh lockout and THCdown can work again.



Ok that is fine, the MiniTHC has an input to lock the THC, so that could easily be connected via the AntiCorner Dive I think :)
Hood

See this is what happens when we're sloppy with terms.

Remember Hood that you're using the CSMIO. Anti-dive in "Mach" is like all the other THC functionality, it's in the Parallel Port driver/pulsing engine. How it works and how it's configured is completely irrelevant to you. You need to find out how the CSMIO (anti-dive in this case) works and is configured and what (if any) external signals or control functions it has.

Remember this has NOTHING to do with Mach or the plugin that allows Mach to communicate with the CSMIO. All and any THC functionality will be in the CSMIO's firmware. It's THAT you need to find out about.

Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 01:24:36 PM
Dave,

Divot at the end, you could try using m10px and m11px to turn your torch on and off, and change your post processor to extend your torch travel a little.... So the machine motion does not slow down before the torch goes off.


Divot at the start.... Sorry you are stuck there unless you can pierce in the waste (hole centre, out of the part or art in your case.... Nice website must say)



I have spent days messing with combinations of torch off early, lead-in, lead-out, over-burn, and so on. I can get it pretty good i think but there is no online library of divots (yeah i know, it's hard to believe) to compare results with so what i get may indeed be really good or totally carp. I have many threads on many forums and no real results apart form my bog-standard go-to of 4mm perpendicular lead-in with no over-burn and 2mm arc lead-out. Trouble is with all the combinations of settings available there are thousands of things to try, most of which are useless ;)
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 01:57:07 PM
Dave, did you have a look at the PDF I posted a forum page or two before?

(I'm out of ideas)
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 02:05:30 PM
HIYA RObert , the problem with a lot of those articale is they were developed using a very high end plasma NOT you basic DIY with a low end air plasma unit. 

Your best friend at this end is TEST AND TUNE and keep good records.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 02:16:06 PM
Dave, did you have a look at the PDF I posted a forum page or two before?

(I'm out of ideas)

Yes, thanks, i have seen that before but as TP says, its high-end stuff but i guess some of the info will down-scale to our size equipment.

what would be really useful is a standard test piece  that could be passed around forums so results could be compared - it may be that 90% of what we all seek is not possible and if everyone got the same results on the same part it would prove it.

just a thought.
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 02:40:00 PM
Well I'm sure we all have one, I'll post mine later, a 2" square with two radiused corners at opposite ends of different radius with a large hole in the centre and a smaller hole off to one side with a rectangular tooth shape cutout....

It's what I always start off with, with new plate or setup to test.

It tests everything shapewise I will throw at my machine except long cuts, or really thick cuts.

Bread and butter for me is 1.5mm to 4mm, occasional 6mm but I'm not into armour plating my real hobby (landrover)

Keep working toward turning hobby into business...  paycut from dayjob... But may be more enjoyable.... Retirement business maybe in future.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 02:49:19 PM

Keep working toward turning hobby into business...  paycut from dayjob... But may be more enjoyable.... Retirement business maybe in future.

Already trying that idea ;)

Care to post up your file?
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 03:29:10 PM
Here is my submission for the Test piece.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 03:45:14 PM
Hmm, odd, do you scale that when importing ??

Tried it here and sheet cam says it 6mm wide by 5mm tall, might need surgical laser to cut that one ;)
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 03:54:47 PM
6" x 5"?

My offering here... (in mm)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 04:18:32 PM
Yep good old inches, D'oh!

Got both files cammed up and will be testing them saturday.

Post results pictures here or elsewhere?

Thanks
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 04:20:26 PM
Ohhh... I never cut the small hole.... It was on there to sort of see how small a hole you can make... Give it a go if you wish though
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 04:24:32 PM
HUM that should be in inches as I never work in Metric here. DID you select inches when you imported it into Scam?

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 04, 2016, 04:26:05 PM
I did the second time ;)
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 05:23:46 PM
Ian, yes I suppose the external controller can throw up issues like that. I think Plasma is fairly well supported in the CSMIO controllers but suppose the only real way to know for sure would be to use it.

So if we go back to the corner dive control in as far as Mach when using the PP, is it simply an output that switches on/off or how does it work?

As for my plasma build itself, as said it will be a while away before I can start on the actual table. I did however get a cabinet from a friend which I will be using as the control cabinet, pics below are not that great but I think it will suffice.
Have managed to get some wiring done here at home, have managed to fit everything on it that I will need including the wee computer :)

Also a question for everyone, what size motor are people using for the Z axis?


Hood
Title: Re: Physical buttons for plasma
Post by: BR549 on February 04, 2016, 05:31:48 PM
Hiya Hood, The anti corner dive is an internal function for mach3 LPT. When you turn it on it looks at teh combined vel of XY and IF it falls below what you preset the Speed for it locks out the internal THCdown function from working. It can still do THCup though. When they speed get back above teh preset then it allows teh THCdown to work again.

NOW whether that works with teh CSMIO controller I do not know. You would need to ask  the manf of CSMIO that question.

(;-) TP

Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 05:34:33 PM
Ah ok, so no LEDs or anything?
Will ask Wojtek whether the CSMIO fully supports the Corner Anti-Dive and will post back if I get a reply.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 04, 2016, 05:36:12 PM
Stepper motor:60BYGH301B  
https://www.cnc4you.co.uk/Stepper-Motor/Nema23-3.1Nm/Stepper-Motor-3.1Nm-60BYGH301B-Nema23
 http://cnc4you.co.uk/resources/Stepper%20Motor%20Nema%2023%2060BYGH301B%203.1Nm.pdf

Drives: leadshine am882h (ac or dc)
http://www.leadshine.com/productdetail.aspx?type=products&category=stepper-products&producttype=stepper-drives&series=AM&model=AM882

Poweraupply, 50v ac / 650va
Buy direct from the manufacturer, very highly recommended
http://www.vigortronix.com/ToroidalTransformers-DualPrimary2x115V.aspx
Title: Re: Physical buttons for plasma
Post by: Hood on February 04, 2016, 05:42:20 PM
Thanks Rob, just trying to get a handle on the size of motors used to see whether my wee servo will do. It is quite hard to try and compare specs of servos versus steppers but it kind of gives me an idea.
The motor I now plan to use shoved the  X axis slide about no probs on the wee connect lathe I had and could plough a parting tool into steel quite easily without struggling, so I think it should be fine.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 05, 2016, 02:20:52 AM
3.1Nm on my Z and CNC4YOU.co.uk DSP stepper drives
Title: Re: Physical buttons for plasma
Post by: Hood on February 05, 2016, 01:11:28 PM
Thanks Dave, what Vel and accel are you getting, also same to Rob and anyone else who cares to join in :)

I just bought another motor with a 10:1 gearbox so may end up putting a bigger motor on anyway as I had been contemplating having a drilling head there also so I could do small holes that the plasma wouldn't manage, thats for the future though.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 05, 2016, 02:25:15 PM
I had it set originally at 1200mm/min and 900mm/s/s acceleration, this seemed a tad low so I pushed it up until it screeched which was at 2000mm/min so i backed off to 1500mm/min. The acceleration went way up to 5000mm/s/s before a screech so backed that down to 4000mm/s/s which gives an estimated 0.3g and 744rpm measured with a tacho on the motor shaft. I think thats ok for a 3.1Nm Nema23 motor. Steps per mm is 1000, 2mm pitch screw direct drive.

Dave
Title: Re: Physical buttons for plasma
Post by: BR549 on February 05, 2016, 02:46:01 PM
Dave if you ever get a chance try a 5-8mm pitch on the screw/direct drive . As is you run out of motor speed/accel  before you run out of THC responce speed (motor stalls first)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 05, 2016, 03:17:51 PM
Yes it would be a pretty easy swap too, 10mm trapezoidal screw fitted i think, will make a note and look out out for a steeper thread, i think 744rpm is right at the top of the scale for a nema23 on 50v and getting it lower would be good.
Title: Re: Physical buttons for plasma
Post by: Hood on February 05, 2016, 04:41:36 PM
Thanks for the numbers Dave.

What travel, dia etc of screw do you use. I may have a spare 10mm pitch ballscrew if I can find it, not seen it for a while but I know I bought more than one. It is 25mm dia screw and a fairly long nut on it and it has been shortened, prob about 100-120 travel, I originally had it fitted to the quill on my very first retro, a manual Bridgeport.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on February 05, 2016, 05:01:58 PM
I'll get my specs later in the weekend

Suggestion on quicker z axis... Plus machining
http://www.ebay.co.uk/itm/251405700798

I've got to do a redesign on mine first (I know and am greatful for Russ' offer.... But I really need to do a redesign first)

I must say I am impressed with the ground and info covered and gained in a thread about buttons... Haha
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 03:31:31 AM
Thanks for the numbers Dave.

What travel, dia etc of screw do you use. I may have a spare 10mm pitch ballscrew if I can find it, not seen it for a while but I know I bought more than one. It is 25mm dia screw and a fairly long nut on it and it has been shortened, prob about 100-120 travel, I originally had it fitted to the quill on my very first retro, a manual Bridgeport.

Hood

Thanks for that, mine is only 10mm dia, i have emailed the maker as they do offer a 10mm x 4mm pitch screw that is a direct swap-in, that would be a nice easy upgrade. Its a two-start version of the standard unit.
Title: Re: Physical buttons for plasma
Post by: stirling on February 06, 2016, 05:20:09 AM
Hood - 3Nm size 23 stepper motors. direct drive via mod1 rack n pinion with 15 tooth pinion.

Question to ballscrew/linear rail users - how do you protect them? Honestly not being funny here but unless you use bellows and such I just don't get how they survive.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 05:49:36 AM
Same R&P setup as mine Stirling, I have 4Nm motors though.

I was pondering ballscrew when I built my table but your point was one of the reasons i did not use them, the rack on my gantry (X axis) is exposed and I have concerns about that. The Y racks are nicely tucked away under cover plates on the sides and so far have remained clean. I fitted double wipers and muck scrapers on my linear blocks - it tightened them up a bit but hopefully will extend their life, I also grease regularly to flush any muck out.
Title: Re: Physical buttons for plasma
Post by: robertspark on February 06, 2016, 07:36:20 AM
My Z axis is the same as Dave's .... 10mm dia x 2mm pitch trapezoidal leadscrew with a delrin nut
(Marchant Dice)
http://www.worldofcnc.com/collections/trapezoidal/products/delrin-nylon-round-right-hand-lead-single-start-nut
http://www.worldofcnc.com/collections/trapezoidal/products/tr10x2d-trapezoidal-right-hand-spindle-leadscrew-din103-c15-c35

I did consider a 4mm pitch.... but would like to make a bit more of an improvement, as my travel distance is about 135mm and I have a 4th Axis (modified rotary table) that I'd like to integrate for doing lobsterback exhaust parts and roll cage / hoop bits.

My X and Y are HTD 5mm pitch belt drive, with direct 20T pulleys.

All belts are mounted on the outside of  the rails (opposite to the plasma torch) hence shielded from muck

The leadscrew is not really in the direct line of blowback as there is quite a bit in the way.

Belts are tensioned using some manufactured springs similar to what the 3d printer crowd use with their 3mm belts.
http://i.ebayimg.com/images/g/tEgAAOxyBotTWzgV/s-l300.jpg

Backlash is not much at all and not really something I'm concerned with too much with a blunt tool like a plasma (but I'm not doing artwork etc)

I have about 0.16mm (~6 thou) of backlash on the belt drives, but I suspect its the nature of using belts

All my motors are the same as posted earlier 3.1Nm.

I have been fiddling with my settings this morning given I can get higher acceleration that what I was running X and Y and both higher velocity and acceleration Z.... although I need to test it under instant acceleration of (slap and go) of THC as I dont think I had it set up the best following earlier discussions on here as I've learnt a lot.

My X and Y run 10uStep (0.05mm/step [~2 thou], Z is 1/2 step (0.005mm/step [~0.2 thou / step])

The Z can clearly been improved upon given that sort of resolution is not required, I did consider full step (but not sure what others run step/ unit wise on a plasma table)

I don't use backlash compensation.... but I can and hence the 10uStep resolution would tie in nicely with the ~3 steps of backlash compensation.

Again not sure what others do....
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 09:13:37 AM
ok, some results from the test files...

3mm HR steel, 45A, 4100mm/min, 107v

On one of the very small holes i forgot to reduce my lead-in length so scam removed it for me hence to nasty divot.

I'm still messing with actions on corners, they are a mixed bag i think, slightly better internal corners but a little wiggle when the speed drop kicks in.

Be interesting to see how they compare.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 11:04:43 AM
A little video i made this morning on 3mm Alu, at 1.10 you can hear the Z axis skip the rapid part of the G28.1 routine, it does this a lot but only when doing G28.1 I have tried using the MDI to do it and also the keyboard but so far it only ever skips on G28.1 and not every time either ???

I didn't realise it at the time either but from 1.10 onwards it is doing the last cut on the part and the material warps up about 15mm and the THC tracks it nicely so I think that's working OK, you can also see the motor spindle at the top and see it dip slightly on the corners, I have no idea if it only dips a little because tip-saver or anti-dive kicks in or just that its rounded the corner before it goes too far but it only drops a little.

Could really do with inset synced video of Mach screen :)

Too many things to watch in a short time

https://youtu.be/fgg7F8H7vno (https://youtu.be/fgg7F8H7vno)
Title: Re: Physical buttons for plasma
Post by: BR549 on February 06, 2016, 12:55:24 PM
Slow down teh G28.1 speed in Mach3 or lower the accel rate of Z. First I would change out teh feedscrew to a much courser feed. You are simply overspeeding the motor.

Title: Re: Physical buttons for plasma
Post by: BR549 on February 06, 2016, 12:59:59 PM
I also noticed the second part cut better than the first part.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 01:11:40 PM
I tried MarchantDice - they do the 10x4 screw but no nuts?
Have emailed another supplier, will find out monday hopefully.

In reality all 4 of the parts came out really well, when it screws these up it really screws them ;)
I used to send them out for laser cutting, but once i got the plasma working well, i found i could do them myself and trouser the profit :)
All it takes is a couple of minutes with a small file to clean them up, practically dross free, this is the 45A nozzle at 30A, 2400mm/min but is very material specific.

As for the Z speed, it really is odd that I can not make it do it manually -MDI or jogging, only when running G28.1, hopefully double the screw pitch will halve the speed so motor will only need to do 370rpm to get the same movement, 744rpm is pushing the envelope a bit i think.
Title: Re: Physical buttons for plasma
Post by: BR549 on February 06, 2016, 01:19:34 PM
Ideally with a z stepper you try to get 1" of motion per 2-4 Turns of the stepper. At 2 turns you can normally outrun your THC at top speed and at 4 you should be well in the range of GOOD and not stall teh stepper
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 01:23:07 PM
Great, thats an upgrade on the cards for certain.

Thanks TP

What about the test cuts, any views?
Title: Re: Physical buttons for plasma
Post by: BR549 on February 06, 2016, 01:41:58 PM
I will have to wait until I get back by the shop (;-) to cut them.

(;-) TP
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 06, 2016, 01:52:04 PM
No worries, just ordered the new screw and nut, found another supplier :)
Title: Re: Physical buttons for plasma
Post by: Hood on February 07, 2016, 03:49:12 PM
Thanks Ian, 3nm seems to be the norm for a stepper on the Z :)
Hood
Title: Re: Physical buttons for plasma
Post by: stirling on February 08, 2016, 06:09:06 AM
No worries. TBH I've used around 3Nm steppers for all the axis on routers, plasma tables I've ever built. One stop shop - can't go wrong. (Sorry if I'm teaching granny to suck eggs here but as you're a servo guy - if you go steppers make sure you go for around 3mH inductance).
Title: Re: Physical buttons for plasma
Post by: Hood on February 08, 2016, 07:47:08 AM
Thanks Ian, unlikely to go steppers on this, I put them on the coil winder as servos were of no benefit and more expensive but I hate working it, bloody noisy things these steppers :D

Just got a reply a wee while ago from Wojtek, here is what he said when I asked if the CSMIO supported Mach Plasma functions.
Quote
All our controllers can work with a plasma cutter.

The Anti-Dive feature is supported by the controllers as well.

To the Anti-Dive function we have added a pause which is executed at the moment when X and Y axes get proper speed. 

Not really sure what the pause is about as I am not (yet) a plasma guy.


Hood
Title: Re: Physical buttons for plasma
Post by: stirling on February 08, 2016, 08:52:54 AM
bloody noisy things these steppers :D

I kinda like it - singing a little tune as they go bless 'em.

Nope - as written, the pause thing makes no sense to me either.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on February 08, 2016, 09:14:24 AM
Be interesting to find out what thats all about - i would the THC back on as soon as the speed is back up myself.
Title: Re: Physical buttons for plasma
Post by: BR549 on February 08, 2016, 10:29:33 AM
Yes but does it do BOTH anti dives or just one. The pause would be THC delay . The THC stays OFF for teh pause period to allow the torch arc to stablize after pierce. Then when it is stable and cutting the THC turns on. IT keeps teh torch from diving on pierce.

Dave I hear that Torch Diving will be an olympic sport next time (;-)
Title: Re: Physical buttons for plasma
Post by: Hood on February 09, 2016, 02:51:59 AM
TP, I asked if the CSMIO supports all of Machs Plasma functions especially Antidive and that is the reply I got, so I presume so.
How do you set the two types of Antidive?


Regarding the delay, when I got to a computer and looked at the email I saw they added a screenset with the delay DRO added on, still not quite sure what it is for but here is the pic they sent, 1mS seems short.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on February 09, 2016, 05:30:58 AM
Hood - AFAIK Mach3 THC anti-dive is plain simple ignore THCdown signal if the actual speed (of any axis) is less than the set % of feed.

They may well have added "pierce time anti-dive" and that MAY be what they're referring to. Personally I didn't read it that way but that's just me.

Whatever, the 1ms doesn't seem to fit with that somehow. I'm wondering if for some reason they've decided that when a slowed axis gets back up to speed, rather than immediately enable THC down commands again, they insert a delay. Can't see why at the moment but that's more how I'd read what they've written.
Title: Re: Physical buttons for plasma
Post by: BR549 on February 09, 2016, 11:52:58 AM
OK lets try it this way.  THC delay. When the torch first fires teh Arc volts are very unstable and can be as high as 200-300 volts and may take a few 100 ms to stabilize back down to normal. IF the THC is active at that time it willl sense teh high voltage and tell Mach3 to LOWER the torch. YOU DO NOT want it to do that.  SO teh THC delay delays teh THC going active until the dwell time is over THEN it turns on the THC for control. At that time teh Arc volt should be stable and the THC can take over control of Z without causing torch dive.  IF you settings are correct that is (;-)



(;-) TP
Title: Re: Physical buttons for plasma
Post by: Hood on March 05, 2016, 09:57:20 AM
Well not had much time  but am starting to weld up the frame today out of some 3 x 3 x 1/4 box that I did a deal on :)
Have also fallen heir to a steel shipping container so now have a home for the plasma :)
I have decided on a tilting design as it would have given me more room in the back workshop and even though I will be in a container now I will just keep the tilting design as it will make access easier to the far end if need be.
Also have the control cabinet almost wired  so a couple of pics and I better get back to the welding.
Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 05, 2016, 11:59:23 AM
Nice control cabinet, luv the keyboard.

Is that a water table tray, my concern is that it will not work for downdraft??

I would also fit some hard stops so that the tilting system can jam solidly against them to remove any twist in the tilting frame.
Title: Re: Physical buttons for plasma
Post by: robertspark on March 05, 2016, 12:28:18 PM
2p suggestion.... have you thought about offseting your two Y axis so that you get more travel use of your table?   As its drawn, offset toward the back of the machine, given as its shown your torch will be on the front, hence can reach the front rail of your table at the front but may be 100mm from the back of the table?

Is the rear of the table not going to catch on the frame (around where the rails are) when you tip it up, so you may need to offset the table pivot point further forward?

(arm chair smart a$$£""£ I know, sorry).

That way if you offset the Y rails back, they can act as the horizontal stop (but it would tip up the other way.

Also you need to think about how you will lock the table whilst you are loading plate or it may tip up.

The central rail may also become consumable (the central slat support rail, as the cutting power of your torch may exceed the offset depth of where the rail starts).... maybe using angle iron will improve your build time for the slats (but the cost would go up)   I'll post a picture of my slats later may help someone out for an idea in the future.

10 engineers, 10 alternative solutions
Title: Re: Physical buttons for plasma
Post by: Hood on March 05, 2016, 03:17:04 PM
Thanks for the replies.

Quote
Nice control cabinet, luv the keyboard.

That is the keyboard I had on the wee lathe, the only pain about it is it has keys for WWW. And Smily faces, must have come out of an Internet Cafe or something.

Quote
Is that a water table tray, my concern is that it will not work for downdraft??
It is just a tray, no water. Tell me more about the best way to do for downdraught as I know absolutely nothing about it. :)
I was planning on having a fan in a box below and have some form of seal when the table in normal position.


Quote
I would also fit some hard stops so that the tilting system can jam solidly against them to remove any twist in the tilting frame.

The Y axis will be made of 100mm x 100mm x 6mm steel box joined with 100mm x 100mm x 8mm angle so I dont think it is going to twist much but it will be against an angle at the rear and I will have  bottle screws at the front to tension it. If I do run into issues then I can always put in support legs.








Quote
2p suggestion.... have you thought about offseting your two Y axis so that you get more travel use of your table?
As its drawn, offset toward the back of the machine, given as its shown your torch will be on the front, hence can reach the front rail of your table at the front but may be 100mm from the back of the table?
Not 100% sure what you are meaning but I think I have what you are saying, see first pic.

Quote
Is the rear of the table not going to catch on the frame (around where the rails are) when you tip it up, so you may need to offset the table pivot point further forward?

As you can see on the vid there is clearance, I have made the frame transparent in the vid. The outer frame was originally going to be 100mm Alu box so that is why it shows bigger than the back rail.
https://www.youtube.com/watch?v=3UIgj_XVgQI&feature=em-upload_owner


Quote
Also you need to think about how you will lock the table whilst you are loading plate or it may tip up.
As you should see in the vid it will come against angle and although not drawn I will have bottle screws to tension down the front, and as I mentioned to Dave legs will be fitted if required.

Quote
The central rail may also become consumable (the central slat support rail, as the cutting power of your torch may exceed the offset depth of where the rail starts).... maybe using angle iron will improve your build time for the slats (but the cost would go up)   I'll post a picture of my slats later may help someone out for an idea in the future.

I have a small gap from the top of the slats to the top of the angle supports, see second pic,  it is 5mm, do you think I should increase that?

Pic below of the inside of the container and the progress so far on the frame. To the right you should also just about be able to make out the profile rails I snagged from a friend, they are not perfect condition but should be fine for a plasma (I hope anyway :D ) They are 35mm wide, so quite substantial and bloody heavy.

The Gantry I will make from 4” x 4” x 1/4” 6082t alu, hopefully it will be rigid enough, if not then I can double up on it.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 05, 2016, 03:30:30 PM
OOPS, no third pic ::)

Here it is.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 05, 2016, 05:23:32 PM
To get the downdraught to work you need air - LOTS of air, my little 4x4 uses 3000cfm and could do with a little more, thats a 12" axial fan on a short duct venting outside, I have to keep the door or window open for replenish air.

It needs a large plenum below the table to funnel the flow into the fan/s mine is an inverted pyramid but i think a square box would probably work. The fan needs metal blades as it will be dealing with sparks etc.

Title: Re: Physical buttons for plasma
Post by: Greolt on March 05, 2016, 08:55:41 PM
Only a little thing. 

Maybe face the racks downward.  It is such a dirty process.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 06, 2016, 03:32:38 AM
Only a little thing. 

Maybe face the racks downward.  It is such a dirty process.

Very dirty, get the racks upside-down and also cover the linear rails somehow, the crap get everywhere but luckily falls downwards instead of floating about so simple covers over the top of motion work well.
Title: Re: Physical buttons for plasma
Post by: Hood on March 06, 2016, 04:25:51 AM
Ah Ok, sounds like a lot of air needed, I may have to rethink that. Wonder if maybe water will be a better option after all, just have to pump it round to alleviate the hydrogen risk. Maybe even just a water slide, ie have water just coming out a pipe along the shallow edge so it flows down into a tank below and gets pumped round. Filtering may become an issue though ::)


Regarding the racks, not set on the direction of them yet, they were that way due to the swivelling but I have actually redesigned that part so that the table sits 100mm higher so it will not be a problem, just havent redone the drawing.
I do have bellows from the glass machine but they are covered in grease inside so I have not inspected them yet. Not sure if they are fire retardant or not but will test it out.

I was thinking about things last night and I am wondering if, now I have a proper home for the plasma, whether I really need the swivel. I will put the frame in place today and put the Y axis on top and see if I reckon there will be enough room in front, it will only be about 500mm but that may be enough.

Hood

Title: Re: Physical buttons for plasma
Post by: beefy on March 07, 2016, 05:33:42 PM
Hi Hood,

for reasons of contamination I would consider having your gear rack on the outside and with the teeth facing down. As they are in the drawing you have gravity letting dust, etc settle on the teeth, as well as any sparks (abrasive slag) from the cutting.

The linear rails will be much easier to keep clean and lubricated but gear teeth are just a bunch of nooks and crannies.

Keith.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 08, 2016, 02:22:09 AM
I fitted the optional double seal and scraper kits on my plasma linear rails, seemed a good idea.
Title: Re: Physical buttons for plasma
Post by: Hood on March 09, 2016, 05:53:06 PM
beefy, yes Greolt pointed that out. I have bellow covers but still not had a chance to really look at them and see whether they are suitable (flame retardant). I will however be having the track pointing downwards as I have decided I have enough room so do not require the swivel table.
I got a wee bit done at the weekend, frame is basically finished and hopefully this weekend I will get the Y axis profile rails fitted and maybe even get the X axis cut and fabricated.

I read back through the earlier posts as I remember mention of fans etc and I see it was Robert who posted some info, will have to quiz  you more about this ;)



Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on March 09, 2016, 07:32:45 PM
Hi hood, I think Dave has got an extra zero in the 3000cfm (~1.2m3/sec) number above from a 12" axial fan.

From the day job, you could try to improve the capture airflow by using a set of vent grilles or slats below the cutting bed that are 60degree upside down. V shaped slats with maybe 1.2mm copper cladding over the top so the plasma kerf metal spray does not stick to them

You could also place a piece of plate over any unused parts of the table and this will increase the airflow over the used bit of the table.

The rough rule of thumb would be 0.5 to 1m/s per square metre of table...but you need to consider how much of your table is covered in plate normally...   You also need to add a bit for leakae plus fan performance.

Look for mixed flow fans... Stuff like vent axia powerflow fans will get you better performance than an axial fan (airflow at pressure)... Axial have very little pressure (head) capability.

Rob
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 10, 2016, 02:30:46 AM
My apologies, the fan rating is 3200cubic metres per hour so almost 2000cfm.

http://www.ebay.co.uk/itm/201523622666 (http://www.ebay.co.uk/itm/201523622666)


;)
Title: Re: Physical buttons for plasma
Post by: robertspark on March 10, 2016, 03:36:30 AM
Dave & Hood, funny thing doing posts after midnight.... gives you time to think a little (note to self, do before opening keyboard... [or mouth])

Dave, 3200m³/hr = 889 l/sec, & yup that is an axial fan.

Problem with axial fans is they have very little pressure displacement across the fan as said above, and manufacturers like to quote airflow numbers with the fan tested without any ductwork on it / or induced pressure loss (free air displacement).... hence when looking at a fan curve such as the one below, you can see that some manufacturers will choose the point of most airflow at zero pascals of pressure displacement at the far right of the curves (in day job be very suspicious of any fan manufacturer not publishing a fan curve for a fan but just quoting one number without a corresponding pressure displacement).

http://www.cibsejournal.com/wp-content/themes/cibsejournal/images/2011-12/images/figure-1.png

If you are adding ductwork on to it (flexible / ridgid) you need to consider the pressure loss (even roughly), and also the termination (louve, or even free air discharge), and also the intake.

(I'll try to do this over a few posts, if anyone is interested)



Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 10, 2016, 04:04:09 AM
Interesting, luckily i have kept my ductwork to 12" on either side of fan - as short as possible so i should be at near fan capacity for flow rates.
Title: Re: Physical buttons for plasma
Post by: robertspark on March 10, 2016, 04:13:51 AM
How big is your table Dave?

Sorry Hood, can't remember (and 29 pages is a bit so search through...), how big is your table?
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 10, 2016, 05:08:08 AM
Mine is a massive 1250x1250 cut area ;)
Title: Re: Physical buttons for plasma
Post by: Hood on March 10, 2016, 08:41:13 AM
The cutting area will be about 2700 x 1700.
Was thinking maybe having 4 funnels like in drawing below, would give quite steep sides and could have a tray underneath with a fan in or maybe even 2 trays/fans, thoughts?

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 10, 2016, 09:16:44 AM
Is it at all possible to get the gantry on the short axis ??

Trouble with tip-up table and fans will be disconnecting the duct work each time.
Title: Re: Physical buttons for plasma
Post by: robertspark on March 10, 2016, 09:18:16 AM
The steep sides are good... It's called the angle of repose, although the metal is molten.

I've tried to find the angle of repose for iron filings, but can't find the link now or source, but 60 degrees seems to be a number from somewhere.

Also think about what you intend to cut... Stuff with coatings can give off toxic fumes (galv etc)... Hence better to use new plate than second hand... Which I know you are not but someone following this might)
Title: Re: Physical buttons for plasma
Post by: Hood on March 10, 2016, 10:43:59 AM
Dave,
it is going to be a fixed design now, well as long as my welds hold up that is :D
Don't have enough steel to have it the other way, could have got more but I have it done now.
Pic below.

Rob,
 One side of the cones is 58 degrees, the other 68, so should be close.
It will be all new stuff I am cutting and no coatings. Mainly 316 stainless and 5083 Alu.
 
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 10, 2016, 02:00:41 PM
Stainless fumes are very bad news when plasma cut, I thinks its called hexavalent chromium and is carcinogenic, also la is pretty rough too i think, this is why I went for as much ventilation as I could fit in and run with the window open, even in winter to allow for make-up air.

Good idea on going fixed bed ;)
Title: Re: Physical buttons for plasma
Post by: Hood on March 11, 2016, 05:18:58 AM
Aye, Alu is not too great, fume wise,  either.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 13, 2016, 03:22:36 PM
Got a bit more done to the table, mounted the Y axis profile rails, well sort of, only have a few cap screws in them and may have to shim a wee bit.
Got the Alu cut  and bored for the trucks and the X axis, had a lot of interruptions today, think I am going to have to park my car around the corner :D

Oh also got a pendant made, not a huge fan of handheld pendants but as my arms are not 3m long I am going to need it.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 15, 2016, 04:58:21 PM
Had a look at the bellow way covers today, they do not catch fire easily, had to hold a lighter to them for 30 or more seconds before there was anything amiss. They didnt actually catch fire but did start to melt slightly, so not sure how well they would stand up.
I am however wondering how likely I am to get hot sparks on them. For the Y axis the cutting surface would be 100 mm or so below the bellows and I would also have an extra plate of about 100mm between the cutting surface and the bellows, see pic as I may not be explaining very clearly.
 The X axis would be the same height above, maybe slightly more.
Would hot sparks be likely to still get to the bellows?

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 15, 2016, 05:04:47 PM
Wont get any sparks up there, there is a fan of sparks from where the jet enters the plate, they travel along the surface pretty much. If doing wiggle or ramp piercing in thick stuff, you can get a rooster-tail at pierce time but the sparks go cold very quick.
Title: Re: Physical buttons for plasma
Post by: Hood on March 15, 2016, 05:40:30 PM
Thanks, sounds good then, just have to haul the bellows out the box and see if I have enough or indeed whether they are all in good condition.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 22, 2016, 04:32:56 PM
Been too busy to get any more done :(

One thing however that I am wondering, do you normally adjust the current for different thickness of material or do you just keep it cranked up?
 I have been doing some hand cutting and all I see is if you use a lower current for a given thickness it means it just cuts slower. With hand cutting I am obviously not getting a uniform feed so cuts will not be as good as when CNC'd, so maybe I am just not noticing the difference when I try lower or higher currents.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 22, 2016, 04:47:06 PM
Some systems ramp the power up and down in the cut, I cut a job tonight where it could have been used apparently - inside square corners on 12mm plate, these usually end up a bit tapered due to the arc-lag in the inside corners. Ramping up the current just in the corner is said to help this, my system is too basic for that feature though.

There is a sweet spot between power density (nozzle size and current), material thickness and speed - get it right and good cuts will follow.

Hand cutting is a mile away from CNC cutting ;)
Title: Re: Physical buttons for plasma
Post by: robertspark on March 22, 2016, 05:05:09 PM
One current setting, just set your feed and go.

My hyperthem 65 from the US fell through... Looking for a 45... Probably better for a home shop anyway
Title: Re: Physical buttons for plasma
Post by: Hood on March 22, 2016, 07:35:03 PM
Ok thanks for the replies, hopefully things will quieten down for me and I will make some progress with the plasma and start having fun :)

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on March 22, 2016, 07:37:29 PM
Dave, like the choice of picture.... Dr'nk! Haha
Title: Re: Physical buttons for plasma
Post by: Hood on March 26, 2016, 03:49:00 PM
Are you guys driving the gantry from both sides or just one?
I was planning on having a rack at both sides but I got the gantry bolted in place today and I am thinking I will be able to just drive from the one side as it seems to be keeping itself square.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 26, 2016, 04:00:20 PM
If its more than about 300mm wide, drive both sides.

Slaved motors would be the way forwards, have Mach auto-square the gantry on ref.

It may feel firm but when Mach is doing its thing with a plasma job in thinner (<12mm) steel, the whole table will be shaking on tight turns etc, you will be surprised how violent things can get on thinner stuff and cutting intricate designs - I have some parts with grass cut on one edge, its basically a saw-tooth cut and even on 3mm sheet it will shake the hell out out my table - one motor will just anchor one end of the gantry and t'other will be pissing in the wind ;)
Title: Re: Physical buttons for plasma
Post by: beefy on March 26, 2016, 05:03:15 PM
Got to back up what Dave said.

Let's do some maths to illustrate the problem. Assuming a cut speed of 6000 mm/min. That is 100mm per second. If you could write some test code that made you gantry move 5mm then reverse and come 5mm back, and repeat, the gantry would be changing direction and moving 5mm 20 times per second.

If you can picture that you can get an idea of the rigidity needed if you plan to do any thin stuff. Actually, if possible you also want to keep the gantry light so the inertia of fast direction changes doesn't try and move the table. I look at some of the gantries for plasma and they look heavy. That's OK if you don't need fast cut speeds.

A look at Hypertherm cut charts will show the cut speeds can get higher than that on thin stuff. I'm actually gobsmacked that Hypertherm are not realising this issue and coming out with a cutter that allows us to keep the cut speed down on thin stuff. We need low amps and a tiny cute little nozzle with a very narrow kerf. The Finecut nozzles just don't cut it and the speeds can get right up there.
Title: Re: Physical buttons for plasma
Post by: Hood on March 26, 2016, 05:03:58 PM
Hopefully the table will be pretty solid once finished but you are probably right about the gantry, especially as it is 3m wide.
I was just surprised how rigid it was with it bolted down.
I don't plan on having two motors but can if I find it needs it.
What I was planning was a rack and pinion at both sides and a tubular shaft running through the 4inch Alu gantry and belts from that to the pinions, the motor will drive one side of that shaft.
The rack/pinions are good quality helical ones so I hopefully will never need to square things.

Also bought a Trafimet machine torch for the plasma, bloody expensive, nearly dropped at the price :D

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 26, 2016, 05:07:08 PM
beefy, yes I think that will be the case.
My Gantry will be fairly light, it is 4inch box with 1/4 wall 6082, the profile rails will add a fair bit to it mind you as they  are 35mm wide rails and there will be two.
Time will tell I suppose.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 26, 2016, 05:44:20 PM
3m of 35mm rail x 2 plus box section is going to weigh, a lot ;)

My table was designed to reach 9000mm/min as that is top speed for the PM45, so far I have got up to 5000 and that was scary !

With the tube connecting your side gears, watch out for torque causing a twist as the direction changes, with only one motor it will need to be big - servo's ??

If not, watch your top shaft speed as big steppers don't do well at speed or acceleration.
Title: Re: Physical buttons for plasma
Post by: Hood on March 26, 2016, 05:58:43 PM
The Alu will weigh about 18Kg, the rails probably a wee bit more each.
The frame however is fairly sturdy being made out of 3 and 4 inch steel box with 1/4 wall, so plenty of mass there and if need be I have a steel cabin housing it that it can be fixed to :)
It will be servo driven via a 10:1 gearbox so max cont torque available would be in the region of 20Nm and peak 70Nm peak.
I have some heavy wall tube that may do the job but if not a solid shaft will probably be employed although I prefer to keep the weight down if possible, will have to do some calcs and see but I do know the original machine that the racks etc came off had a 30mm dia solid shaft of about 4m.
 It will just be spinning at a few hundred RPM max .
Using two motors would add more weight to the gantry than a solid 30mm dia shaft would be anyway.

Hood
Title: Re: Physical buttons for plasma
Post by: beefy on March 26, 2016, 06:33:16 PM
What I was planning was a rack and pinion at both sides and a tubular shaft running through the 4inch Alu gantry and belts from that to the pinions, the motor will drive one side of that shaft.

Hood

That's what I have right now but I want to change it for dual rack, dual motor when time / money permit.

One thing to consider is torsional twist, especially at higher cutting speeds with 180 degree direction changes. Seeing as you have a length of 3m you could do a torsion twist test. Get the torque specs of your motors (+ any gearing to factor in), and on the bench apply that torque to one end of the tube/bar while the other is held fixed. If that torque twists it, you will probably get that on your table during a cut, possibly leading to shaky oscillations and a scalloped edge cut.

Perhaps a thin wall high strength tube will be more rigid than a solid bar. I know aeroplanes and race car frames can be made from thin wall 4140.

I've messed up plenty with my first cheapy build so if I can help you avoid it, all the better.

Edit:
Oops, just realised Dave got there before me on the twisting matter. Great minds think alike Dave LOL.
Title: Re: Physical buttons for plasma
Post by: beefy on March 26, 2016, 06:42:37 PM
Using two motors would add more weight to the gantry than a solid 30mm dia shaft would be anyway.

Hood

Yes, BUT with 2 motors you have twice the drive power / torque, which would much more than compensate for the extra weight. So with 2 motors your power to weight ratio would be much better.
Title: Re: Physical buttons for plasma
Post by: Hood on March 26, 2016, 06:51:54 PM
What do you not like about the single motor dual rack way?

Regarding the motors, I have two similar torque motors with 10:1 planetary boxes so I can go that route if required but can't see the advantage at this time but as you have the setup I am planning on I may change my mind depending on your answer :D

BTW below is a pic of the original machines gantry, just wish I had a place big enough as I could have used the whole machine and saved a lot of building :D
To give an idea of scale, the energy chain in the pic  is about 200mm wide.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on March 26, 2016, 11:09:40 PM
Both sides (don't forget you want high acceleration too)

Rob
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 27, 2016, 03:55:42 AM
I think tube is better than shaft, IIRC there is no difference in torsion effects. I started off with a little table 600mm square and thought it was cool only having one motor and a 12mm cross-shaft. That was until I tried getting speed and acceleration out of it when you see it wiggling. That table was 100% aluminium too so pretty light gantry etc. OTOH it did allow me to cut the parts for my new machine ;)

I would still go with two personally, but watch out for the runaway effect especially with servos - you need monitoring to ensure both motors move as if one stalls or fails the the other will rack the gantry to death, not important on steppers as they just stall eventually.

The machine in that picture is a bitch ;) Hate seeing stuff in that state.
Title: Re: Physical buttons for plasma
Post by: Hood on March 27, 2016, 04:30:59 AM
Robert,
 don't worry, as far as I am concerned, no matter what type of machine, Accel is King :)
Hood
Title: Re: Physical buttons for plasma
Post by: Hood on March 27, 2016, 04:46:01 AM
Dave, yes tube should be but it will depend on material of tube and material of shaft I think, certainly for same material the tube should be better.
Funny thing is boats always have solid shafts, usually Duplex nowadays.

Wont really have to worry about RunAway, AC Servos are pretty good at monitoring things and always have error signals tied into my E-Stop chain.

If I do go with dual motors I will likely just use one side as a follower to the other.

Yes it is a shame but the machine was bought as scrap to rob the control off, the trucks on the profile rails were in a bad way, only managed to get 5 rebuilt out of 12 that were on it but managed to pick up 3 new on eBay for a decent price. The rails are not the best either, one is excellent, one not too bad but the others have a good bit of pitting. Still accurate enough for a plasma but will be a lot noisier than they should be.

The rack and pinions are all good from what I have seen so far (covered in greases) so that was a bonus.

pic below of rack and pinion.


Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 27, 2016, 04:58:36 AM
Nice :)

With those bits, your table should be built like a battleship!

Somehow I doubt acceleration is going to be an issue;)
Title: Re: Physical buttons for plasma
Post by: Hood on March 27, 2016, 08:14:13 AM
Certainly trying to make it sturdy.
Just took a vid of me pushing/pulling one side of the gantry to see what it is like, camera shaking a bit but everything else seems solid.
https://youtu.be/0fy3EpkbxlY

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 27, 2016, 04:22:26 PM
Interesting experiment would be to mount a laser pointer on each end, facing the far wall, dots close together then swing the gantry and watch the dots wobble in different directions ;)

It may look rigid but plasma will show a deficiency, it's good at that ;)
Title: Re: Physical buttons for plasma
Post by: Hood on March 28, 2016, 03:13:20 AM
I would imagine it would show it moving about a bit.
Hopefully I will get a chance next weekend to get a bit more done, ran out of cap screws yesterday so could only get the top profile rail on the gantry fitted. 35 of them in each rail, wish my Chiron had the room around it to slide the gantry through for drilling and tapping :D

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 28, 2016, 03:21:42 AM
Yep, been there. The X axis on my table was double-width HiWin rail so two rows of parallel screws, drilled and tapped each blasted one of them ;)
Title: Re: Physical buttons for plasma
Post by: Hood on March 31, 2016, 05:24:14 AM
Got the highly accurate ::) lasers yesterday and got a chance to clamp them to the gantry legs this morning.
Not too bad although as said the laser quality leaves a bit to be desired.

https://youtu.be/DaoQKbDxmus

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on March 31, 2016, 05:57:38 AM
Nice :)

That is a pretty rigid gantry there, while you have the lasers, sling some weight on or under the gantry to represent the Z axis & motor, torch, cables, etc then try the same test with the load parked at different points of X from left to right :)
Title: Re: Physical buttons for plasma
Post by: Hood on March 31, 2016, 05:08:16 PM
Will probably just wait until I get the motors mounted, will then be able to drive one side first and see how it performs, if its ok then I will probably stick one sided, if not then I will run a shaft through and fit the rack/pinion to the other side.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on April 10, 2016, 02:21:52 PM
Got a bit more done this weekend, Bored and tapped 76 holes for the second rail and the rack on the gantry. Still have to tweak the rack to get it into alignment but it is close, will make up a  300mm long spacer and use that to slip between the rail and rack and clamp and tighten as I go, it is amazing how much the rack can bend even with it being 30mm x 20mm section.

Robbed the X motor mount and ballscrew from the small lathe and made up a plate for the Z Axis to mount to the trucks and then made up a couple of brackets to mount the motor and ballscrew to the axis.

I will have to chop the torch down a bit in length, it is 400mm long at the moment but I need to cut it down to 280mm, it should be straightforward as it just seems to be an alu tube.

Also fitted a central connector to the plasma and to both torches and fitted a switch to the back of the plasma so that I can select between Hand and Auto torch.
Also got the MinTHC boards fitted inside the plasma and have fitted a RJ45 socket on the back so that I can have a quick disconnect from the MiniTHC if I need to use the plasma on a boat.

Pic below of Z axis.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on April 17, 2016, 12:33:14 PM
Bit more done today, got the Energy chain fitted, wires run/soldered for X and Z motors, wires for limits and also plasma cable run. Also made up a torch holder, you can see it here
https://www.youtube.com/watch?v=OacqX4gjVYQ

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on April 25, 2016, 05:24:17 PM
Got a bit more done over the weekend, made some brackets out of  20mm thick Alu for the Y axis motor and pinion and have belt and pulleys on the way.
I am going to see how it performs driving from one side only at first. If I find it is not good then I can either do what I originally intended and drive the opposite side via a shaft through the gantry or I may end up fitting another motor and drive.
 I have a motor/gearbox that would do, it is a different motor and slightly bigger but I don't think that would matter.

Still undecided about downdraught or water table. Had decided earlier not to use the water due to the problems with hydrogen when cutting Alu but have been doing a bit of searching and it seems  as long as I agitate the water it should be fine, maybe even  have a pump  to circulate the water constantly.
 It seems, from reading, that water cuts down a lot on smoke/dust compared to downdraught but no experience with either so will just have to make up my mind as things are  getting close to that stage.

Anyway a few pics of what I have so far.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 26, 2016, 02:22:14 AM
Looking good.

A downdraught would be best I think - no dross caused by the water hitting the plate, no worries about gases building up, no rust on the machine or plate....

BUT (and thats a big but)

you WILL be standing in a wind-tunnel! I have to have the window or door open for make-up air when cutting, this is great in summer but in winter it brings a new meaning to 'cold workshop'  ;)

There is no smoke at all on my table, even when i cut a 500mm square lump of 12mm plate in the middle of the 1250x1250 bed. The machine is clean -no brown soot anywhere.
Title: Re: Physical buttons for plasma
Post by: Hood on April 26, 2016, 03:13:08 AM

you WILL be standing in a wind-tunnel!

That is one thing I am not wanting, it is cold enough up this way at the best of times, snowing yesterday :D

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 26, 2016, 03:27:15 AM
It's the only downside really, there are ways round it - filter and recirculate but the filters are £££ and will clog eventually, you need a lot of filtration area for the air flow required.

If the intake window was above and to the side or rear of the table then it might not be too bad, mine is behind me about 4' so it gets draughty ;)
Title: Re: Physical buttons for plasma
Post by: Hood on April 26, 2016, 03:55:37 AM
No windows, it is a steel container. I would have to put in some sort of vents so could put anywhere I suppose.
Not keen on the noise of fans, the Esab L405  mig that I use for heavier Alu sounds like a jet engine and it gets on my nerves at times :D

Will have to decide soon but may be able to make it so I can do either, it wouldn't have the sloping sides if that was the case but I have seen quite a few downdraught ones that just have a plenum in the centre, for example like this.
 http://www.ezcutcnc.com/cnc-plasma-cutting-tables-draft-versus-water-tables/

 Probably not the best design but would be relatively straightforward to change between downdraught and water.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on April 26, 2016, 06:01:28 AM
Hey Hood - why not take advantage of the fact it's in a container. Stick a camera in there and have the controls remotely back in your workshop. Load the stock and retire. Maybe a fan on the wall to get rid of the smoke before you go back in.

Bit like my router when I cut MDF - I set it going and get the hell out of there until it's all over and the dust has settled.

Ian
Title: Re: Physical buttons for plasma
Post by: Hood on April 26, 2016, 04:31:22 PM
Ian, I am planning on moving some of my welders out there as well so afraid that is not an option as I will likely be working whilst the plasma is cutting.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on April 28, 2016, 03:39:00 AM
Ah OK. Your dust/smoke extraction is going to have to be REALLY good then. Don't risk breathing ANY of that sh1t - it's REALLY bad for your health.

Ian
Title: Re: Physical buttons for plasma
Post by: Hood on April 28, 2016, 02:37:00 PM
Yes, health is definitely a thing to look after, never think about these things when you are younger :D

I have been doing lots of searching and reading about Downdraught versus Watertable and there are so many conflicting opinions I am just not sure which way to go, some say water is better for fumes, others say downdraught. Most  say cut quality is better with downdraught though.

Anyone who has downdraught have pics of their setup?

Sure someone posted a link to the extractor fan they used, possibly Dave, will have to trawl through the thread and see if I can find it.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 02:38:53 PM
Yeah it was Dave to an eBay link
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 02:41:01 PM
You get a better edge with a water table plus stainless... And that improves with nitrogen (no black edges apparently)

Just what I've read... Sure someone will add some experience
Title: Re: Physical buttons for plasma
Post by: Hood on April 28, 2016, 02:53:38 PM
Thanks Rob, yes just found it.

Regarding stainless, I think maybe the better edge is with submerged plasma but  maybe not.

Going to have to decide what to do soon as I am getting near to completion of the axes etc, not keen on fan noise but if it is the best way then I will just have to put up with it.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 02:59:16 PM
Don't forget freezing water table in the winter.... Christmas break... Unheated container.

Yes has to be submerged as it reduces the oxidisation.

Can you not try the downdraft... Then adapt later?

If you are doing loads of cutting day in day out, or lost of SS or thin metal then yup, otherwise try the downdraft... Place fan in insulated box outside...with long hose?

Rob
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 03:00:23 PM
Hood, I've taken the plunge on one of those po-mo minithcs from Denis, and I had a good discussion with him about the caxis protocol.

Long and the short he has expanded the c-axis protocol which has reduced the amount of data required to send the TH voltage setpoint to the controller.

I have been playing around with a sheet cam post processor and sort of cut pasted, and created my own for the po-mo minithc which allows you to store the voltage setpoint with the tool, and send it to the controller under tool change.

I also now have a pmx 45, and noticed an error in the manual regarding feedrate in the conversion from in/min to mm/min but this has allowed me to create few feedrate equations that match the pmx manual settings.  All you do is tell it the material, thickness and ampage (30/45) and it will work out the feedrate directly in sheetcam... Must admit not finished the function on this one in the post processor.... And it's only for the pmx45.

Rob
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 28, 2016, 03:02:31 PM
The fan is just a bit of the noise - add in the compressor, the plasma sound itself and you have a lot going on. But at the end of the day it's a machine so I just ignore it ;)

I do have the extract controlled by the system though - comes on just as the height sensing starts and goes off 5 seconds after the last cut stops, i have a delay timer that keeps it on during rapids etc.
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 03:04:40 PM
Don't need a delay timer, just issue an m09 code to the sheetcam function finish().... Done
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 03:10:19 PM
... Presuming that is you turn the fan on with an m07 or m08....

Under the onpendown() function
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 28, 2016, 03:31:28 PM
:)

Yes i use M08/9 for the fan but i put the code elsewhere in the post as i use the torch as a drill sometimes to mark spots for drilling later - no point having fan on then so a little jiggery-pokery with the post and throw in a timer and it works exactly how i like it :)
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 03:48:43 PM
Ahh...

Been trying to understand the post processors for sheetcam.  Interesting stuff... Some of them make me wonder why did they do this or that but very interesting when you begin to look into it

...no expert by any stretch on the imagination.... Still learning (always)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 28, 2016, 03:53:17 PM
I'm a country mile away from expert level, I generally just try something and look at the code after then tweak to suit ;)

I use VB6 at work for programming and its a bit like that, just a touch more temperamental ;)
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 04:04:40 PM
I like lua... Bit more forgiving than C or CPP

You looked at m4 or waiting for plasma or something else to make it of interest?

Sorry hood, hijacked thread
Title: Re: Physical buttons for plasma
Post by: Davek0974 on April 28, 2016, 04:10:14 PM
Nah, I'm happy with my Mach3 setup - works so why mess with it ;)
Title: Re: Physical buttons for plasma
Post by: Hood on April 28, 2016, 05:40:14 PM
Ok think I will just make a simple tray, maybe 500 deep and have a fan similar to Daves stuck in the back of it. Will see how good that works and take it from there.
It might work ok, especially if I can have some thin sheets to place on the top to reduce the surface area when cutting smaller pieces.

Robert,
 interesting regards the C-Axis. The manual I have says it is not implemented and to ignore. Do you have any more info on it?

Have you used the THC yet?

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on April 28, 2016, 07:44:02 PM
Hood, have a look at the current eBay listing, the manual has been updated (I told Denis he should be shouting about it to try to sell it more)... Note you'll not have the latest firmware, but all that means is that you have a longer packet to send of unused information which will take about 1 second minimum at tool change.... My suggestions just bring this down to the useful code.
This link may or may not work...
http://m.ebay.co.uk/itm/MiniTHC-torch-height-controller-THC-/322003269901?nav=SEARCH

No not yet hoping for a run this weekend.
Title: Re: Physical buttons for plasma
Post by: Hood on April 29, 2016, 02:45:47 AM
Thanks Rob, that is indeed a different manual.
Will have to look at it and see whether it may be worth getting the firmware updated, not sure whether that would require it to be sent back or maybe it can be updated here.

Look forward to hearing how it goes, it certainly looks like a competent THC but.......

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on April 29, 2016, 03:09:39 AM
I've got a plan to connect it up to my frequency / function generator, and oscilloscope to try to see the point at which it can't keep up with the change in input voltage and also the response delay between input and output.... That is the plan... See what happens

Your one will work with the c-axis but it will require the longer (left hand column) of the message format which has a whole lot of redundant info that the THC does not use (hence my question to Denis about shortening the string)

Apparently when it had modbus it was able to output the datastring to the hypertherm powermax 65, 85 and 105 in modbus ASCII characters (serial)... But no one ever seemed to buy the interface and use it.  I said to Denis he was just not marketing it well enough and telling people what it did... Hence better manual section.

See what the scores on the doors are with the tests I guess.

Rob
Title: Re: Physical buttons for plasma
Post by: Hood on April 29, 2016, 07:25:27 AM
Keep us posted with the results ;)

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on April 30, 2016, 06:11:27 AM
Saw this fan on eBay, any thoughts on its suitability?
http://www.ebay.co.uk/itm/Industrial-Duct-Fan-Cased-Axial-Fan-Commercial-Extractor-450mm-4-Pole-/191541803309

Also anyone know where I can get 15 core (or more) curly cable, suitable for a hand held pendant,that can extend to 3m? Have found lots but none can stretch to that length.

Hood
Title: Re: Physical buttons for plasma
Post by: stirling on April 30, 2016, 07:30:57 AM
Re: the cable: You could always stick a jack box at the mid point and plug your coiled cable into that - voila - you'd only need 1.5m.

Or - how about using infrared - no cable needed.
Title: Re: Physical buttons for plasma
Post by: Hood on April 30, 2016, 01:21:50 PM
I had thought about having the wire halfway and strapped along the front of the table and may end up doing that. If I do then I probably won't require curly cable as I can make it a good fit so it doesn't sag.
Regarding IR, not keen on wireless for controlling a machine and as this is with the CSMIO MPG module I not even sure if  it would be possible.

Hood
Title: Re: Physical buttons for plasma
Post by: robertspark on May 04, 2016, 09:02:22 PM
Well tried bench testing to minithc (thought it would be easy... First failing)

Basically fed it a slow 2v square wave at less than 0.2 hz.

This allowed me to see that it was reading the voltage about 2 volts higher than it was (calibrated scopemeter), although this is without the plug in pmx45 50:1 adapter.... Hence there may be some effect from the filter circuit in that on the read voltage.

Unfortunately I was not able to get a specific cutoff frequency of saturation, and it seemed relatively low, but this I suspy was from feeding it a 2v to 2.4v square wave switching from zeo to the set voltage which is a little unrealistic given the voltage would be jumping from 0v to 100 or 120v on an increasing frequency.... Basically I need to stop a smaller varying input voltage 0.02v to 0.05v .... With an offset of 2.4v....

And I've not got the inclination at the moment....but may come back to it
Title: Re: Physical buttons for plasma
Post by: Hood on May 06, 2016, 02:56:17 AM
Oh well, suppose we will find out how well it performs once one of us gets it hooked up to the plasma :D

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on May 07, 2016, 05:17:01 PM
I have not got power to the cabin yet other than running an extension lead. I am waiting on the boatyard crane to move the cabin round a bit so access will be easier for material, once they do that then I will run in some 3 phase.
 Today however I decided to power up a drive at a time from single phase supply.
 
 The racks and pinions on both axes still need adjusted properly but it was fine for this test.

Got the Y set up first, did a rough tune and set up the Index homing. It went reasonably well but I am probably going to have to drive both sides as at 20m/min rapids and  jogging back and forth in very short bursts I could see the far side getting out of shape. I will see how it performs at the fastest I will ever cut, probably 6-7m/min, and if it looks reasonable I will delay driving the second side until later.
I can then decide whether a rod/tube  through the gantry or a motor on the other side will be the best way to proceed.

Anyway here are a few vids,
First is the X axis going at roughly 20m/min.

https://www.youtube.com/watch?v=SfoXmz3j8Jw

Next is Y axis doing the same

https://www.youtube.com/watch?v=ZeuYbyCnFs0

Lastly  it is the Y axis doing the Index homing.

https://www.youtube.com/watch?v=bof2LoSPxoE

As can be seen in the vid I am monitoring the encoder via a netbook connected to the drive, the encoder count is spot on each time, jitters between -1996 and -1997 encoder counts. The tuning is not perfect yet but it was good enough for today's tests.
The prox I am using to trigger the Index homing is on the non-driven side so it shows that there is not any flex at the lower speeds of the homing (5m/min)

Hope to get the Z Axis tried out tomorrow, hopefully the tiny motor will be up to the job.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 08, 2016, 03:24:29 AM
Looking good, don't forget - it's not the speed that will stress it but the acceleration. ;)
Title: Re: Physical buttons for plasma
Post by: Hood on May 08, 2016, 05:22:22 AM
Yes, well mainly, velocity will also affect things as having a very high accel but a lowish  velocity will likely not stress things as much as it would having a higher velocity with the same accel.
At the moment I have it so it takes 1/3 second to get the 20m/min

Hopefully will get the Z tested out this afternoon, may even get a chance to try all 3 axes together, that will depend on whether the extension cable can handle things, not worked out what the current draw would be off of one phase.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 08, 2016, 08:39:01 AM
As a general setting I have found the 1/10th rule to work pretty well - say you have 2000mm/min velocity then you set 200mm/s/s acceleration.

From my own tests it works pretty well as a bog-standard setting to work up from.
Title: Re: Physical buttons for plasma
Post by: Hood on May 08, 2016, 03:13:39 PM
Happy to say the wee motor on the Z works well.
Have it set to 5m/min and 5000mm/s/s rapids.
Here is a vid of it homing with a G28.1 and then doing a few up and down rapids.

https://youtu.be/ZEd4OS09KM8

Just had enough time to set up the home to current value in the drive and give it a quick test. It is looking promising but I will need to do some more testing to make sure it will be good enough for touching off.
Here is a vid of the initial test.

https://youtu.be/8oM4dTONGyc

Torch lowers, touches material, current increases because motor is starting to push against the material and it then stops and  sets that as home in the drive, it then backs off an amount I have preset.

Hood
Title: Re: Physical buttons for plasma
Post by: RICH on May 09, 2016, 06:07:57 AM
Hood,

Here is what my friend did for ventilation using a small axial fan. The plasma is in his basement and the smoke alarms would go off.
His machine is smaller in size bed around 3 x 4'. Above the  of the machine is a plenum, just thin sheet metal with the outlet located in the center and 6"
duct to axial fan which exhausts to the outside. A clear plastic curtain on each side which can be drawn up and down ( same as one would use in the house )
can be drawn down to enclose the table perimeter. Works great.

I know that you don't desire wireless but the X box is used and works great as the table is away from the pc and pc is also away from the plasma machine.
Say 8 to 10' feet or so. By the way he has a water bed below the grate.

Got to go. Back in a few hours,

RICH
 
Title: Re: Physical buttons for plasma
Post by: Hood on May 09, 2016, 08:38:41 AM
Thanks Rich,
 think I will be going for downdraught and likely wont have water either. Bit more work involved in the downdraught but likely less messy and safer as I will be doing mainly stainless and Alu.

Regarding the X Box, not going to happen I am afraid, stuck in my ways I am afraid. ;)

Got a few mins to try the homing again with different settings and I think it is going to be a bit too sensitive to current values, too low and it can think it has homed just whilst accelerating and too high and it would push thinner material. That might not be too much of an issue as I will hardly ever do any less than 3mm but you never know.
I could drop the accel on the homing routine and it would probably be fine, will see how it goes.

Saw someone with an air cylinder and a switch, could have been Dave? It looked to work well so may investigate that further

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 09, 2016, 09:00:55 AM
Yes, the pneumatic fired switch/probe was my brainchild but modified and developed with the help of a few on here ;) It does actually work very very well, I can get IHS on the thinnest metal without distortion as the switch triggers on about 10gm I think it was. The rest is just a little 25mm stroke cylinder, a valve and the switch plus some macro code to do the IHS - this takes the routine away from SheetCam and makes any changes to the switch offset a one-step alteration - it just uses the switch offset value on the settings screen :)

Here's a vid of it working... https://youtu.be/FV6WpuQjFE0 (https://youtu.be/FV6WpuQjFE0)


I was wondering about the current-sense method not being delicate enough, it only seems to appear on the big toys that spend all day hacking thick plate.
Title: Re: Physical buttons for plasma
Post by: Hood on May 09, 2016, 03:14:30 PM
Thanks, will maybe end up doing something along those lines if the current value homing proves too much for thinner stuff.
My tests at the moment are not great as I do not have the metal sitting on a steady platform, I might rig up something a bit more solid at the weekend and get some further testing done.

I have also decided to put another motor on the opposite side of the gantry rather than have the shaft through it. Thinking  I will just use the follower mode for the servo drive as it is very configurable and should be reliable.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on May 14, 2016, 02:16:45 PM
 I got the brackets for the slave axis motor made up and fitted through the week, also got it all wired with the exception of some I/O in the drive.
I was originally just going to use the follower mode in the drive and connect it directly to the Y axis drive which would be the master. However I took a look at the CSMIO plugin and read a wee bit about it and it has a nice feature.
What you can do is have two switches on either side of the gantry and you can then set in the plugin to measure the difference between switches. You home the axis then go back into the plugin and you will now see the difference in distance and can then enable the plugin to use the difference when homing.
Best bit however is if you find your gantry is not quite square to the other axis you can adjust the distance in the plugin and it will offset one end of the axis by the amount you have added or subtracted from the home switch distance.

Waiting on a few prox's arriving so have not been able to test it out yet but hopefully they will arrive next week.

Also got all my panel buttons configured in the macropump, have 9 all together that go via the CSMIO/Mach and the other two are Control which starts the computer and then also powers the 24v for CSMIO etc. The other button is a Limit Override button as my limits work external to Mach via my Safety relay so to back off a limit I need a physical Override button.

Anyway the buttons I have via the Macropump are
Start
Hold
Stop
THC On/Off
Reference
Reset X  (Fault Reset)
Reset Y  (Fault Reset)
Reset Z (Fault Reset)
Touch Off material (For doing the homing routine in the servo drive)

Got to try and get the boatyard pinned down to shifting my cabin, I can then get the 3 phase in and start making the tray/extraction/support bars.

Really looking forward to the day I can actually start cutting some metal :D




Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 14, 2016, 02:44:31 PM
Sounding good Hood :)

Also an apt thread as it looks like i'll be needing some physical buttons for my mill conversion project, thinking of using arcade style joysticks for X, Z & Y jogging, plus the usual cycle start, hold, stop etc. Will be a similar setup I think as i'll be using the CSMIO/A unit.

Are the Macropump details in this thread?

:)
Title: Re: Physical buttons for plasma
Post by: Hood on May 14, 2016, 02:50:44 PM
The CSMIO controllers have a kind of inbuilt Modbus for the I/O. It means you can use the I/O as normal in Mach if you want but obviously there is not enough I/O in Mach so you can also use the I/O direct from scripts or brains.
I do most of the I/O via the macropump, here is what I have in the plasma macropump.

Cycle = GetInBit(91,0)
Hold = GetInBit(91,1)
Halt =GetInBit(91,2)
THC = GetInBit(91,8)
Touch = GetInBit(91,3)
Ref = GetInBit(91,4)
ResetX = GetInBit(91,5)
ResetY = GetInBit(91,6)
ResetZ = GetInBit(91,7)

If THC Then
DoOemButton (123)
Sleep 500
End If

If Cycle  Then
DoOemButton (1000)
End If

If Hold Then
DoOemButton (1001)
End If

If Halt Then
DoOemButton (1003)
End If

If Ref Then
DoOemButton( 1024 )
While IsMoving()
Wend
DoOemButton( 1023 )
While IsMoving()
Wend
DoOemButton( 1022 )
While IsMoving()
Wend
End If

If Touch Then
SetOutBit (90,8)
Sleep 500
ResetOutBit(90,8)
End If


If ResetX Then
SetOutBit (90,3)
Sleep 500
ResetOutBit(90,3)
End If

If ResetY Then
SetOutBit (90,4)
Sleep 500
ResetOutBit(90,4)
End If

If ResetZ Then
SetOutBit (90,5)
Sleep 500
ResetOutBit(90,5)
End If


There is info on the CS Lab site on how to use the I/O you will find it here.

http://www.cs-lab.eu/en/artykul-128-Digital_and_analog_IOs__configuration__its_easy.html
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 14, 2016, 03:05:21 PM
Nice, thanks for that.
Title: Re: Physical buttons for plasma
Post by: mc on May 14, 2016, 03:14:13 PM
OK, I'm going to have to ask. How does the magnetic breakaway for the torch get aligned?

I've been wondering about it since I seen the video, but it's not clear in the video. I'm guessing there's some kind of tapered locating tabs, that allow it to locate positively, yet still breakaway if hit from the side?
Title: Re: Physical buttons for plasma
Post by: Hood on May 14, 2016, 03:41:14 PM
Dave
 remember to have Pots for Feed and Spindle Overrides :)

mc
There are 8 magnets so it more or less aligns itself. If I had glued in the magnets it would have been perfect but I milled pockets with a small ledge at the base so that the magnet could not get pulled out, that brought a problem where the plates could move very slightly as the magnetic pull was not as strong as it would have been if they were touching. Solution was to bore two 5mm holes in the lower plate and thread the top plate and fit setscrews that I had domed on the lathe.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 14, 2016, 05:14:43 PM
Yeah, lots of ideas for the panel - that's the fun bit;)
Title: Re: Physical buttons for plasma
Post by: Hood on May 15, 2016, 05:25:21 PM
Today I tested out the THC via its Test Function. Couldn't get it to work at all, the LEDs for Torch Up, Down etc worked but the Z would initially just give a small movement then nothing. Tried all sorts of settings in Mach but still nothing. That is when I got the light bulb above my head, I have the MPG module for the CSMIO/IP-S  and it was set to Z MPG. I switched it to the Off position and still nothing but then I switched to Y, moved it then switched back to Off and after that the THC testing worked fine. THC control must use Machs Jogging and with the MPG module setting Mach to MPG mode the THC commands don't work.

  So that could be a potential problem, as long as I remember to switch to Off before the THC starts to issue commands then it will be fine but if I forget then it will not work.
 To get round this I have had to wire a button on my hand held pendant as in the CSMIO instructions so that to get to MPG mode the button has to be pressed, without the button pressed it reverts to Jog mode. Having the button on a hand held pendant is a good thing really but as I normally don't have the pendant and just use the MPG on my panel then I normally don't utilise the button and instead wire it differently with diodes  and have an Off position on the rotary switch for the odd occasion I want to jog via keyboard. 

Ok so that problem solved I then tried to get my head round the THC buttons on the screen, took a bit of messing but I think I now understand how they work.

I set the speed to 100% and it works great, have seen mention of 50% for steppers and 90% for servos but  I don't have a problem with 100% it seems. Video below of it moving 80mm with the 100% setting and using the MiniTHC test functions.

https://youtu.be/N5hRuZsIglc


I also took a few pics of the breakaway torch holder for mc as my description probably didn't make much sense.
You can see the setscrews from both sides in the pics and also you can see a prox I have there that will be used to E-Stop Mach if the holder breaks contact.


Hood
Title: Re: Physical buttons for plasma
Post by: Hood on May 16, 2016, 07:23:14 AM
Still not got the prox's yet but did set up the Index from the master and slaved drives and enabled Index Homing on the Y, and just used the one switch that is on one side of the Y.
I enabled the plugin to look at the difference between switches, now obviously there is no difference between the switches themselves as there is only one, however there is a difference between the Index so I was curious to see if it worked.
 It did , it was -1.118 units and it went well when I homed I could just barely see  the far side move back but it did. I then decided to make it -10.118 and homed again. This time I could clearly see the far side move back after the nearside had stopped but it was even more evident when I disabled the drives as this let the gantry jump back to its relieved position.

Here is a vid showing it.

https://youtu.be/2o2QPdYWD-I
Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 16, 2016, 07:31:33 AM
Nice,
how does index homing function?
Title: Re: Physical buttons for plasma
Post by: Hood on May 16, 2016, 07:36:52 AM
You have a switch for each axis and the axis moves to the switch then backs off and then looks for the Index pulse from the encoder and stops at it.
It means the homing is deadly accurate as the switch accuracy (within reason) does not come into the equation as it is only used as a trigger to tell the control to start looking for the encoders Index pulse.
That is the way most industrial machine home and it is the way I have all of mine homing.
With the machines that I do not have the CS-Lab controllers on I do it in the servo drives themselves as my servo drives support that feature, it is however much simpler if the controller itself supports it and the CSMIO does :)

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 16, 2016, 07:54:12 AM
Nice, that sounds damn good.
Its coming together slowly now.

Does it only need the one switch or 1 homing & 2 limits per axis

Thanks
Title: Re: Physical buttons for plasma
Post by: Hood on May 16, 2016, 09:09:21 AM
I am not 100% sure but I think it requires a separate home switch for each axis.
On my machines I have a Home for each axis then 1 limit for each axis but the limits are in series. The one home switch is located roughly central on an axis and the triggers are at either end, thus the need for only 1 Limit switch per axis rather than 2.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 16, 2016, 09:59:10 AM
Ok, thanks, so it cant use combined home/limit like basic Mach does?

Will have to find some very heavy duty switches for this one i think.
Title: Re: Physical buttons for plasma
Post by: Hood on May 16, 2016, 10:21:07 AM
Just set up the Z prox on the plasma to home and limits and it seems to work.
I have in my mind something about there being a problem with that on the wee lathe  but it certainly seems ok on the plasma so looks like you can.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 16, 2016, 10:23:54 AM
Nice, I like simple :)
Title: Re: Physical buttons for plasma
Post by: mc on May 16, 2016, 03:30:55 PM
Thanks for the photos. Certainly satisfied my curiosity!
Title: Re: Physical buttons for plasma
Post by: Hood on May 30, 2016, 05:04:09 PM
Got the container turned round, decided to position it differently from my original intentions. That brought a problem as it meant the fan would be going out the side which is now hard up against my GRP cabin or out the end which is right against a wall. So had to haul the plasma out, birl it round and get it back in. It was a bit of a task but with a few 50mm dia pipes and a crowbar and jack I managed it.

Spent the last two weekends getting three phase run in and the container wired. Bit of a pain as there is no way to fix anything other than drill holes through the container or weld bars for tying the cables to but have it all done now and never blew anything up :D

Made up a limit switch similar to Daves for touching off the surface, not sure if I need to raise it a bit as it is quite a bit lower than the torch when extended but if I do then it is just a matter of boring  and tapping 3x M5 holes.

Pics below of cylinder and guide rod, was going to buy a double rod cylinder but when I saw the price I decided to use a single rod one I had and make it into a guided one :D

Dave,
 how do you do the touch off? Is it in the M3 macro or do you have seperate moves for the offset move, the G31 then the move back?

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on May 31, 2016, 02:25:51 AM
Looking good :)

I have a subroutine called "HeightSense.tap" that has something like this in it...

G91 (switch to incremental mode)
G01 X28.00 Y4.00 F6000 (position probe switch)
G90 (switch to absolute mode)
M1050 (trigger the probe cylinder)
G28.1 Z5.000 (probe the surface)
G92 Z0.000 (zero the Z axis DRO)
M1051 (raise the probe)
G00 Z#15045 (apply the probe switch offset from M6 tool change)
G92 Z0.000 (zero the Z axis)
G00 Z5.00 (raise the Z axis for travel)
G91 (switch to incremental mode)
G01 X-28.00 Y-4.00 F6000 (put the axes back to where we came from)
G90 (switch to absolute mode)
M99
%

All the codes were pulled from SheetCam and now it just calls heightsense.tap where it needs to do the probing - no more messing with all my code files when i change  the switch position etc ;)

M1050/M1051 just activate/deactivate the output that has the cylinder solenoid on it.
My switch is a very low force one - about 10g force - i can sense the height of very thin material without moving it.

The tool change M6 bit has two offsets in it - one for 30A tips and one for 45A ones, I have a button on screen that just alternates between each tip and tells me what i have installed.
Title: Re: Physical buttons for plasma
Post by: Hood on May 31, 2016, 07:25:25 AM
Thanks for the info Dave, think I may do something similar but have it in the M31 macro, if I can manage to do some VB :D

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on June 05, 2016, 11:23:14 AM
Been a busy week but managed to get some done this weekend.
Have got the compressor moved into the container, fitted a solenoid valve, wired and plumbed.
Modified the M31 probing macro from CS-Lab and it seems to be doing all I need.
All I will have to do is have my post processor insert the relevant code and it should be good to go.
Code would be
M31 R-50 F5000

The R-50 is telling the CSMIO to probe a max of -50mm from current position. I should really have -130 there as that is the travel of my axis but for first tests I just put a lesser number.

Here is a vid of the first few tests on 1.3mm brass plate.
https://youtu.be/gu86SHWwTu8

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on June 05, 2016, 11:30:34 AM
Looking nice there Hood, very satisfying when that feeler gauge slips under the tip every time ;)
Title: Re: Physical buttons for plasma
Post by: Hood on June 05, 2016, 11:34:49 AM
There is a bit of variance, because I am using the M31 macro it reports the position the switch is hit at.
 I ran it about 20 times and recorded the Z position and each one was different, it reports to about 8 decimals but the difference between largest and smallest was about 0.04mm which should not concern a plasma.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on June 05, 2016, 11:38:46 AM
Nah, won't make any difference even 0.5mm would work ok if using THC.
Title: Re: Physical buttons for plasma
Post by: Chaoticone on June 05, 2016, 12:21:38 PM
Looking good Hood!  :)
Title: Re: Physical buttons for plasma
Post by: Hood on June 05, 2016, 05:09:54 PM
Thanks Brett, hopefully wont be too long now before I get it finished, still trying to decide on how I will do the downdraught tank/tray/thingy.

Hood
Title: Re: Physical buttons for plasma
Post by: Fit0 on October 10, 2016, 04:49:08 AM
Hi Hood,

Have you made any more progress on your plasma table? If you've had some more time to get acquainted with it, what are your impressions of the MiniTHC? Would you recommend it? I also have a CSMIO controller and also agonised between using a MiniTHC (which I haven't bought - yet) and adapting a divider to my plasma cutter and using CSMIO's analog THC function.

Your thoughts on the matter will be greatly appreciated.
Title: Re: Physical buttons for plasma
Post by: Hood on October 10, 2016, 02:50:13 PM
Afraid I have just been too busy to get this finished. Hoping to get some time in the next two or three weeks as I could really do with getting it running. Have 3 Cheetah Marine Cats to fit out nearer the end of the year which will need a load of Alu and Stainless cutting and it will be a good test.

Hood
Title: Re: Physical buttons for plasma
Post by: Fit0 on October 10, 2016, 04:54:18 PM
Looking forward to your reports!
Title: Re: Physical buttons for plasma
Post by: Hood on November 19, 2016, 06:05:50 PM
Had a lot on and also been a bit under the weather and not been having much luck with this :D
Got the plasma finished enough to start testing but having all sorts of issues which I am unsure whether are me or not due to me never having used a plasma before.

First problem I have is I am just ruining nozzles in short order, seem to be fine one run and then not another. What seems to be happening is the pilot arc starts and then the plasma arc, just as it should then sometimes it seems to go all soft on the arc and then it will come good again. Problem is the nozzles is now screwed :D
 Been doing some looking around and it seems it may be double arcing. I have tried quite a few things so far, increasing the pierce height, increasing/decreasing the air but still it happens every so often. Pics below of a nozzle that had done one or two cuts then had the problem and that was it screwed :D

 I have also been having a load of problems with the M31 macro, getting EPID errors at times, why I have no idea but CS Labs have all of my Mach folder and are having a look to see if they can find the issue.
The computer I am using is the Via Pico that was on the wee lathe so it is loaded with all sorts of crap, think I will do a fresh install of XP and a fresh Mach and set things up from scratch to get rid of all the junk, hopefully that will help.

Also having issues with the THC, again not sure why but it looks like the signals from the THC are fine going by the arrows on the display, they change up/down extremely fast but the Z axis seems to have a lot of lag in it when under THC control so it is looking like there is a problem between the THC and the IP-S, may even be computer related so the clean install may help that.

Here is a vid showing the cut with the soft arc which I think is Double Arcing, you will see it starts fine, goes kind of soft and spread out then goes fine again for the cut.
https://www.youtube.com/watch?v=QDTFbefEEi4

If anyone can suggest a fix for this I would be delighted to try it out. If I make it to the workshop tomorrow I will try reducing the current to see if that makes a difference.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on November 19, 2016, 06:16:13 PM
Here is one that went fine. Obviously I had the travel a bit better than the earlier video but if I get that arc problem when doing this speed the axes have travelled half way round before the arc comes good again :D
https://www.youtube.com/watch?v=NhezLzf2wFw

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 20, 2016, 03:49:54 AM
Hiya Hood, welcome to the world of plasma - a world of pain :)

Apologies if i am preaching here but...

I am the opposite to you - I started in CNC plasma first then progressed to the luxury of CNC milling ;)

Double-arcing will kill consumables fast, what torch/system are you using ?? I ask this because I wasted many hundreds of ££ and hours and hair by using poor plasma systems at the start because i thought i could save some £££ - I was wrong, I worked through three systems before i got it going, nearly made me give up and throw the towel in. The ONLY thing that saved me was splashing the cash on a Hypertherm 30XP which was later upgrade to a Hypertherm 45 - once you go Hypertherm you never go back ;) Hypertherm torches do not double arc, at least i have never managed it.

Next is air supply - it must be dry, totally dry and oil free, I have a little refrigerated drier as well as the usual water traps in line.

Next is THC - the torch needs to find initial pierce height repeatably and accurately, then it must drop to cut height rapidly and accurately when the Arc-Ok signal is seen by the controller.

I won't mention motion as your table has servos so should be better than my stepper one.

Don't bother using the "book specs" for cut speed or voltage, just use pierce height and cut height, the rest is all measured on your table, let us know and i'll explain how its done if you want.

Once that lot is sorted out, the fun starts - plasma is never a cut and run system it seems - I still get bad days when it refuses to cut or blows a tip, but these days are between many days of good running now so i don't mind so much.
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 07:32:07 AM
Dave,
 torch is a Trafimet S65P machine torch.
Machine is a TecArc Opticut 65.

Air supply seems ok, certainly no issues when I do the hand cutting. It uses a Trafimet S65 hand torch.
I have a few more things to try such as moving slowly whilst piercing but if I can't seem to get to the root of the problem I will make up a holder for the hand torch and see, in fact I may even set the machine torch up with the long consumables and drag nozzle that is on the hand torch just to see.

Height sensing, initial pierce and final cutting height are accurate so don't think that is the issues, have tried all sorts of different pierce and cut heights as well.

One thing though, you say
Quote
then it must drop to cut height rapidly and accurately when the Arc-Ok signal is seen by the controller
Are you meaning you drop as soon as the arc is started and don't have a pierce delay


Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 20, 2016, 08:00:34 AM
I can't seem to find much as to how that torch strikes the arc - it says it does not use HF but does not say it is blow-back start (hypertherm) or something else.

Have you grounded the plasma to the sheet or the table - use direct to the sheet, at least to start with, this rules out poor return issues.

What thickness steel are you playing with? If its <12mm I would not bother moving the torch while piercing as it will not help, my little 45A will pierce 12mm without moving, just.

Have you any recommended settings for pierce and cut? There is no point in trying random settings here, there is usually only one setting for piercing a certain thickness of a certain type of metal.

Yes, my system has a built in lag (caused by THC, BOB, Mach3) of around 0.3s so until my book tells me i need more than 0.3 I set zero delay. Thinner (<3-4mm) metals need no extra delay. I think i used about 1s delay on 12mm.

What sort of dead-band do you have on the THC, mine is +/- 1v i think, so it does nothing in that area.

The best cut is achieved at the maximum setting for the nozzle in use so if i use a 45A set, i get the best cut at 45A although it will go down to 20A, if i use the 30A set i get the best cut at 30A although it will go much lower, all to do with arc energy density. Air pressure is a fixed setting and needs to be maintained without loss or it drops out.

How are you obtaining cut speed and voltage(height)??

To set mine up for a new material, I turn off THC, set my cut height as per book, then cut multiple straight lines maybe 150mm long with various speeds, looking at dross, cut quality, kerf etc, one of the lines will be better tan the rest - that one is the right speed. Then I cut one more line at that speed and this time monitor the arc voltage on screen (THC still off) - this now gives me the correct voltage.

Both these values are then plugged into the G-Code and the THC and away we go, sometimes a little tweaking is needed but it works. I tend to always have one eye on the screen where it shows Z height when cutting - i am watching for a sudden drop in z height immediately after the THC kicks in - this indicates my voltage wants tweaking a little as the Z gap cant physically change (sheet warp) in such a small distance therefore it must be consumable wear or just a wrong voltage.
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 01:33:35 PM
It is Pilot Arc starting.

Yes, initially thought it was a grounding issue but it made no difference at all.

Never made it to the workshop today so never got a chance to test out with a lower current. The machine is 65Amp but nozzle  is 60Amp so maybe the extra few amps is the reason it happens sometimes and not others, kind of grasping at straws :D

Anyway may make it tomorrow and might get some time to try a few more things.
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 01:34:42 PM
Oh alsmo meant to say I am not using the THC at the moment as it is not working correctly as mentioned previously so until I find the problem with it I have it disengaged.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 20, 2016, 03:41:45 PM
Ok, good the THC is off, one less thing.

Pilot arc is still HF but the arc is inside the torch and not from torch to metal. It won't be the issue though i think as all it might do is cause PC or motion problems and you don't have that it seems.

From the ESAB site...

Double Arc

A double arc is a condition which allows the nozzle to stay in the plasma circuit. As described, the nozzle should only be in the circuit during the pilot arc phase. If left in the circuit, the nozzle will carry cutting amperage which will destroy it.

Double arcing is caused by:

Standing pierce. The torch has to be positioned close enough to the work-piece to allow the pilot arc to contact the plate, so the main arc can transfer. Pierce spatter is ejected at a shallow angle during the initial pierce. As the arc penetrates the material the spatter becomes more vertical. This debris may connect the plate and nozzle, keeping the nozzle in the circuit even when the relay opens to remove it. This scenario may damage the front end of the torch.
Torch in contact with the plate. Cutting thin material. All automatic torch positioning systems utilize some initial height sensing method to position the torch above the plate. One method is the touch and retract method. The torch travels until it makes contact with the plate and retracts to the initial start height utilizing a timer or encoder. If the touch is not sensed properly, the torch may still be in contact with the material due to springing up or material warping. The nozzle will remain in the plasma circuit carrying cutting amperage, damaging it.

Pilot arc malfunction. This can occur if the pilot arc relay circuit fails to remove the nozzle. This can happen either with a shorted relay or resistor. Again the nozzle is left to carry more current than intended, damaging it.

Preventing the Double Arc

Double arcing usually occurs during the piercing sequence.

Some techniques which can help avoid double arcing are:

Creep move. The cutting machine is programmed at a reduced speed to begin machine movement on arc transfer. This speed is usually 5 to 10% of normal cutting speed and is for a given time period. Pierce spatter is being ejected away from the nozzle during this time. This reduces double arcing possibility.

Torch rising during standing pierce. On arc transfer the torch begins to pull away from the work- piece. This allows the pierce spatter to clear the nozzle. This retraction continues for a timed period, and then lowers to correct cutting height after the machine is moving at cutting speed.

Higher than normal initial height pierce (standing pierce). This allows the pierce spatter to miss the nozzle reducing the chances for a double arc. This method of prevention is the least effective.




So....
if you manually trigger an arc in free air, you should only see a low power pilot arc, not the full cutting arc, does your unit have current display? As there is no metal to complete the circuit, the unit should not switch to full power arc, just the pilot, if not  then maybe a dodgy pilot arc relay etc. You probably won't see this when manually cutting.

I would definitely not exceed the rated power for a nozzle/electrode, in fact my 45A unit cuts best at 43A, go figure :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 04:36:42 PM
Dave, nope no display, I think there may be a relay that clicks in then out again when the current is sensed but not sure, will have to listen for that.
The THC shows the Arc Ok only when the current flows with the main arc so that is fine.

Yes, saw that Esab info and there is also a Hypertherm description and that is what started me thinking it may be double arcing.

Did a vid of what happens, also put a good cut at the end of the vid for comparison , exactly same settings and code, one fine the other not.

https://youtu.be/jPcpDsdRcAQ
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 20, 2016, 04:52:52 PM
does look like double arc or failing to switch to full arc maybe.

if you have a clamp ammeter stick it round the work return cable, thats where my current sensor sits, see if it registers full current when messing around.

Even when working right, it can (and does) blow a nozzle sometimes, for no reason it seems, not usually as bad as yours - that is really destroyed. Mine tends to slightly blow out one side - it still cuts but has uneven angularity to the cut. Other times I can go for ages on one set of consumables.

Are you 100% certain there is no water in the air - put a bit of polished metal or a mirror under the nozzle and trigger the air flow for a minute or so, any muck will show up.
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 05:21:22 PM
Did an air test a while back but will do it again. Just used a bit of paper and let the air flow for a while, dry as a bone and no dirty marks, well except my fingerprints :D
Title: Re: Physical buttons for plasma
Post by: Hood on November 20, 2016, 05:22:50 PM
Oh and I think it does switch to full arc as it always comes on strong then on the times it fails the arc goes all spread out and soft before it then comes back strong again.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 02:14:49 AM
Very odd, is there no help from TecArc?

Is there a support group? I can't see one on PlasmaSpider although i would certainly ask over there.
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 03:02:48 AM
Haven't contacted TecArc as yet, not 100% sure where the problem lies as it has only been a short time I have had it running.
I did find something interesting though in the early hours,  Jim Colt saying you get that all the time with Alu and that is what I have mostly been testing with because that is what I have most of.
He said that is why Hypertherm use shielded nozzles on their torches as it is almost impossible to get double arcing. So that now gives me something else to try out. The hand torch has a drag tip so in other words it is shielded. I can try that out on my machine torch and see how it performs, if it is ok I may get a spare drag tip and just remove the castellations  to give me the clearance required for machine cutting, think they are 1-2mm deep.
That may also explain why I have never seen this with the hand torch.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 05:06:45 AM
Jim is 99% right all the time, good guy.

Yes alu is a bitch, I hate the stuff on the plasma.

Cutting the castellations off a drag tip is what i did on the little 30XP unit as it has no machine torch - it works, try it.

HyperT recommend never cutting Alu on the 30A parts as they are not shielded either, i only use these for fine detail on stainless 1.2mm sheet.

Sounds like your on the way hopefully (did i say get a hypertherm ?? ) :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 06:32:35 AM
Well that is not the problem, put the long consumables in the machine torch with the drag tip and still the same.
Currently making up an adapter plate to hold the hand torch and will try that. If there is still a problem then the only thing I can think of is the machine or the something to do with the divider card wiring.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 06:37:56 AM
Thats not good.

Surely the divider card is only active/important when the THC is on?? Or does that send the ArcOk signal too? Still it should not affect the double arc issue.

Have you tried manual cutting with the drag tip again - it may be a problem in the plasma box??
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 08:12:14 AM
It is the machine torch, will have to strip it out of the machine and see if I can find the problem.
Here it is  cutting 1/4 Alu
https://youtu.be/LuIPbX9_qI0

Here it is cutting 12mm steel
https://youtu.be/JsbPASWhYoM
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 08:17:41 AM
Couple of pics of the steel.
Topside and underneath.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 08:37:58 AM
Those cuts look ok, so the hand torch works and the machine torch sucks?

Maybe a short inside or blocked air passages maybe.

I'm still running the hand torch as the machine one was a fair bit more cash.
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 11:11:41 AM
Yes, very happy with the cuts, much better than I had hoped for especially after the initial headaches :D

Yes I have cut a load more tests this afternoon and all perfect. 3mm, 4mm and 1/4 Alu, 2mm, 3mm, 5mm and 8mm stainless and 10 and 12mm steel.

I bought the machine torch because it would allow me to use the plasma manually on boats or things that wouldn't fir on the plasma with the hand torch and leave the machine torch on the table itself, as you say they are not cheap, £300 plus if I recall.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 12:28:52 PM
Yes, very happy with the cuts, much better than I had hoped for especially after the initial headaches :D

Yes I have cut a load more tests this afternoon and all perfect. 3mm, 4mm and 1/4 Alu, 2mm, 3mm, 5mm and 8mm stainless and 10 and 12mm steel.

I bought the machine torch because it would allow me to use the plasma manually on boats or things that wouldn't fir on the plasma with the hand torch and leave the machine torch on the table itself, as you say they are not cheap, £300 plus if I recall.

Yep, the Hypertherm CNC torch was about £500 I recall, It takes seconds to pull my hand torch off the table as the cable is suspended overhead not in the energy chain.

Glad its just the torch - must be a reason, hopefully something simple and fixable, is it returnable?

When it works it's a blast int it :) It opened up a whole world of possibilities for me.
Title: Re: Physical buttons for plasma
Post by: Hood on November 21, 2016, 01:24:51 PM
It will depend on where the problem lies as to whether I can return it or not, if it is from the torch to the extension I joined in then I should be able to return, I never altered any connections as such apart from snipping off the ring terminals and crimping them to the new wires, the main lead/ air hose and connection I didn't touch. I was going to but decided against it and just used a male/male fitting to join them together.
 If the problem lies in my extension then obviously I can't send it back as it will be my fault.

I will strip it off the machine and connect the central adapter plug direct to the original connections and see how it behaves, if it is ok then I may see if I can suspend overhead in some way, do you have any pics of how you did it?

Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 21, 2016, 01:50:52 PM
I will strip it off the machine and connect the central adapter plug direct to the original connections and see how it behaves, if it is ok then I may see if I can suspend overhead in some way, do you have any pics of how you did it?



Nah, too crude for pics - it just loops up from the torch to a bungee cord loop hanging from the roof truss, then back to the rear wall, down and into the plasma under the table. :)
Title: Re: Physical buttons for plasma
Post by: robertspark on November 21, 2016, 11:08:48 PM
Is this the machine torch you have?
https://www.amazon.com/Autocut-PA2211-Plasma-Cutting-Trafimet/dp/B01I247GWK#

Which hand torch do you have?

Did you extend the machine torch lead, if so, by how much?

I suspect that if you rejointed the lead the pilot (high voltage) may be tracking.... How did you insulate each core from each other once you remade them off?


Note some of the hand torches are blowback start, not sure about the machine torches though...
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 03:21:14 AM
Yes that is the torch, Trafimet S65P, the hand torch I have is the hand version of it, the Ergocut  S65.
I extended the machine torch by 4 or 5m.
The power wire was done in a similar fashion to the original, wire crimped to the 1/4BSP hosetail and then it was insulated with self amalgamating tape.
Torch switch and pilot arc wires were joined with crimp tube connectors and insulated with glue lined heatshrink and then the whole lot was wrapped in self amalgamating tape.

Both torches are the same method of starting, Pilot Arc, don't know anything about blowback start so can't say whether they are or not but as said both the same, even share the same consumables.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 22, 2016, 03:44:14 AM
If you extended the lead and air pipe you will probably need more air pressure to allow for the added loss in the longer hose.
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 03:47:26 AM
I tried with different pressures but I also used the flow meter supplied with the torch to make sure there was enough at the torch.
Title: Re: Physical buttons for plasma
Post by: robertspark on November 22, 2016, 04:05:49 AM
Although its not your manufacturer, if you have a look at the hypertherm 65 manual, it provides additional air pressure (as dave says above) requirements for the longer hose.  https://www.hypertherm.com/Xnet/library/library.jsp?file=HYP115403&format=pdf


Blowback start is simply (yes I'm sure there is more to it than this but) .... a "floating" electrode within the torch tip, so that the air pressure drives the electrode gap, and the high voltage between the electrode and the tip generates the high voltage spark   (think spark plug, but with variable gap). edit: after reading Jim's post, the breaking away of the electode from the tip when the air pressure rises, which creates the spark

Hence the air pressure may be your problem with the longer hose given the floating electrode within your torch may not be moving back enough to trigger the arc or with-stain an adequate arc...... note that the current hyperthem range have an electronically variable air pressure (not the PMX45), so I suspect that the air pressure can be adjusted dynamically given any affects from the cutting surface which may cause some variance in the air pressure as the cutting height varies.

All of the above could however be bull.... so take with a pinch of salt as I'm no plasma industry employee just an owner of two (hypertherm) plasma cutters and have read a lot of the hypertherm manuals

blowback start waffle:
http://www.cnczone.com/forums/hypertherm-plasma/181858-cnc.html

better explanation on the HF + blowback start from Jim Colt:
http://www.tractorbynet.com/forums/welding/211108-plasma-cutter-choices-4.html
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 04:32:43 AM
From that link, the one with Everlast guy in it, it says the Trafimet S series are blowback style so that is what I have.
As I said I tried different pressures, here is what the manual states

b) Check air pressure is around 4.5-5 bar (65-75PSI), excessive pressure will give bad
starting, pressure can be reduced to around 4.0 bar if necessary


I also used the flow meter on the torch itself and flow was more than adequate according to it so I must presume pressure likewise.

I will remove the extension and connect it to the central adapter and see if it works, if it does then it seems there may be a limit to the length of lead, if it doesn't then it could be an issue with the blowback parts in the torch itself.

When I asked for a 10m torch I was told they only have them in 6M but they could supply a joining box to extend, what this consisted of I am not sure but would think it just a pipe connection (double male) and 3 terminals to connect the safety wires and pilot arc wire but maybe not?
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 01:41:15 PM
Did the first real job today, parts for a stainless hanging block. Was still using the hand torch and I have quite a bevel on the left and right sides but that is totally down to the torch being ouyt of alignment, other than that it went good.
Vid here
https://youtu.be/t1MEf8A50EU

After I cut the parts I haled the machine torch extension off and connected up the central adapter on the end and tried it out, seems to be working fine although it doesn't seem to be quite as good as the hand torch for some reason, then again never got much time to do further tests, that will have to wait for another day.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 22, 2016, 02:10:29 PM
Nice, glad it's going at last :)

Bevel can be torch too high (wider at top) torch too low (wider at bottom) uneven (torch not true to surface)
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 02:18:38 PM
Don't think it was torch height as the X axis moves were straight and they were sloping the same way on either side, like this /............./   I think if it had been height then it would bevel like this /........\  .
I can actually see the torch is not square, it was just a quick lash up to see if the problem was with the machine torch.

As said the machine torch worked fine on the couple of tests I did but it just seemed a wee bit different, can't really explain but more testing will let me know how it is performing.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 22, 2016, 02:30:34 PM
Great, seems like you have it sorted then.

:)
Title: Re: Physical buttons for plasma
Post by: Chaoticone on November 22, 2016, 04:04:04 PM
Nice Hood!  :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 22, 2016, 06:12:46 PM
Yes Dave, getting there, still have the THC to get sorted out and also the M31 issues but I am hoping a cleanup of the computer will help as it has been running Mach3 for a long time and was used as a testbed so all sorts of junk in there.

Thanks Brett :)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 23, 2016, 02:18:27 AM
What axis were the ePid errors on with the M31?

Sounds similar to my Bridgeport issues with jogging in a tool change - instant ePid fault.
Title: Re: Physical buttons for plasma
Post by: Hood on November 23, 2016, 05:54:14 AM
It was the Z axis, Wojtek got back to me saying the macro needed a sleep 1 between While IsMoving() and Wend. First I have heard of that but he said it was overloading the PC because of the lack of sleep.

Also remember this is not the IP-A so no encoder feedback and that was why I was struggling to see how there could be a epid error as I imagined that would be due to the closed loop of which the IP-S does not have.


Anyway going to reinstall Mach when I get a chance.
Got my BobCAD post altered last night for the plasma and it is looking good so far :)

Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 23, 2016, 06:19:44 AM
Nice :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 23, 2016, 06:51:18 PM
Went to cut a strip off some stainless today and one of the drives has died :D Or at least I think it is the drive, potentially could be a short in the wiring somewhere but unlikely.

Have some spare drives  here at home so not a huge problem, transferred the drives settings file over to one tonight and  will get it swapped out tomorrow.
Title: Re: Physical buttons for plasma
Post by: TOTALLYRC on November 23, 2016, 07:22:49 PM
Dead Drives = Expensive


Spares, PRICELESS

Mike
Title: Re: Physical buttons for plasma
Post by: Hood on November 23, 2016, 07:30:21 PM
LOL, all mine are second hand, don't pay huge money for them, bought two 1Kw ones maybe 5 or 6 months ago as I  had used the last of that size I had on the plasma. Got the 2 for £150 which is more than I usually pay but they are getting less common on eBay now.

Title: Re: Physical buttons for plasma
Post by: Hood on November 24, 2016, 08:15:25 AM
Well put the spare drive on and all is fine :)
One thing though, I always thought the square side of the cut due to the swirl of the plasma jet, was right hand side as the cutter moves away from you. This seems to be the opposite, I cut an internal circle and if I go anti clock that should leave the edge of the hole square and the scrap bevelled but for me it is the opposite, go clockwise and the hole is straighter and the scrap bevelled.
Have I got things wrong or are the Trafimets maybe different?
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 24, 2016, 08:56:53 AM
It all depends on the angle of the holes in the swirl-ring in the tip and if the electrode has a swirl groove like on the Hypertherm electrodes.
Title: Re: Physical buttons for plasma
Post by: Hood on November 24, 2016, 10:18:21 AM
Must be Dave although I am not even sure if they have an angle on the swirl ring holes, will have to inspect closely but they look straight although common sense says they can't be.

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on November 24, 2016, 10:23:13 AM
Just had a closer look and they are angled.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 24, 2016, 10:55:41 AM
Yep, the Hyper electrodes also have a very coarse screw thread up the side but that is also part of the blowback start i think.
Title: Re: Physical buttons for plasma
Post by: Hood on November 24, 2016, 04:52:24 PM
The Trafimet electrodes are just straight and seemingly the S series (which mine are) are blowback start as well.
The actual swirl ring is tiny in the Trafimet torch, about 14mm in dia and about 4.5mm thick with an internal dia of about 10mm. The holes I would guess are about 0.6 or 0.8mm in dia and there are 4 of them.


Made some progress with the THC. Denis asked me to video the axis moving under the test routine in the THC and he said it looked like it was using the accel set in motor tuning wher normally with the PP and other controllers it doesn't. To check it out I drastically reduced the accel and sure enough the moves were very slow in accel.
So he suggested I change my Velocity from 5m/min to 2m/min and change the Accel from 1000mm/s/s to 5000mm/s/s and see if it made a difference. It did, THC now is usable, it still jumps around constantly but it is probably under 1mm in total. I will do some more testing tomorrow if I get a chance or the weekend if not.

The plasma is going to be really handy though, today I had to make up a wee box from 4mm Alu, normally I would have hauled out the evolution circular saw and chopped a bit off the sheet, problem with doing that is it is never 100% square. Today I shoved the half sheet up on the plasma, wrote a quick bit of code to run 950mm in X, 180mm in Y then back on the X. Took about 30 seconds to do the cut and it was dead true :)

Think I will have to see if I can manage to do a few wee wizards for simple things like that as although hand coding is not hard it would be much quicker in a wizard.

Title: Re: Physical buttons for plasma
Post by: Hood on November 24, 2016, 04:56:04 PM
Oh here is the initial THC video I did, as you can see it overshoots badly banging the torch up and down against the Alu.

https://www.youtube.com/watch?v=PqJ2s_2znsQ

Here is the one I did after ajusting the accel and velocity, much improved.
https://www.youtube.com/watch?v=AcdJEg3fL7E

And here is one where I angled the sheet at probably about 20 degrees.
https://www.youtube.com/watch?v=Qo7-F2NGaVY
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 25, 2016, 02:17:02 AM
There a simple plasma shape wizard on the Mach site, Mach Tool Box, that might help you out :)

When you say it jumps about, i think that may be normal, my one does and its pretty sharp - you can feel the Z moves in the table as there is no acceleration its quite harsh but thats what you need. It takes a long time to tune THC correctly, and even then it can be hit and miss sometimes.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 25, 2016, 02:34:55 AM
Here you go...

http://www.machsupport.com/forum/index.php/topic,21395.0.html
Title: Re: Physical buttons for plasma
Post by: Hood on November 25, 2016, 02:51:36 AM
Thanks for the info regards the THC, Denis reckoned it still wasn't good enough but for me at least it is usable now. Or maybe I should reserve judgement until I have tested further at different vel etc.

Yes found the shapes last night as I kind of half remembered Terry doing them. Got them altered to suit the code I need spat out, will test it today :)
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 25, 2016, 03:52:36 AM
On your THC, do you have a start delay - the THC should not kick in until the arc is established & stable on the cut AND the cut motion has started.

The see-sawing you had on vid 1 looks like way too much gain on the Z axis for THC moves, but I am only used to stepper drive THC so maybe your system does not have that?
Title: Re: Physical buttons for plasma
Post by: Hood on November 25, 2016, 07:14:00 AM
On your THC, do you have a start delay - the THC should not kick in until the arc is established & stable on the cut AND the cut motion has started.


Yes you can adjust the delay via the display unit.

Quote
The see-sawing you had on vid 1 looks like way too much gain on the Z axis for THC moves, but I am only used to stepper drive THC so maybe your system does not have that?

There are not many settings available in the THC, seemingly they had a deadband setting in their last THC but removed it from this one as they felt it was not needed. It is fine with most controllers and the parallel port as far as I can gather but because the CSMIO doesn't do things the way the PP and others do, ie the instant motion without accel, then there are problems.

Messed abut a bit today, first tried the plate at about 20 or so degrees and it worked ok, not great but just the same as it was on the flat.
First vid on slope, second on flat.
https://www.youtube.com/watch?v=a2g7olaCXFk

https://www.youtube.com/watch?v=Qrd3KReTxb8

Next I dropped the Vel in Mach further, from 2000 down to 1000 and it was definitely better, still not perfect though.
https://www.youtube.com/watch?v=DP-do2UlfCs

Have emailed CS-Lab to see if they could make it work like the PP does and also Denis at MiniTHC is talking with the engineer to see if they can do anything.
At least it is usable now, that is the main thing but obviously I would like it better.

Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 25, 2016, 08:27:35 AM
Good stuff :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 26, 2016, 06:57:39 AM
Well hit a snag, THC was working ok as in the vids above, not perfect but acceptable. Thing is however I was cutting Alu at 3000mm/min so the cut didnt take long. I then used the same code to cut 10mm steel so the feed dropped down to 1000mm/min so the time basically trebled and that is where the problem arose. The servo drive tripped out about 2/3 into the cut with an Motor Thermal Protection error.
What that means is basically the short sharp constant motion was giving the drive/motor fits and the drive shut down to save the motor.

The manual states a few remedies, see pic below. I may try a bigger motor/drive but I think the real solution would be the second remedy in the list, in other words  to have a deadband so that the motor is not constantly moving. To my mind there is no need for it is the voltage is only varying by a small amount.

Does your THC have a deadband setting Dave?

Hood
Title: Re: Physical buttons for plasma
Post by: Hood on November 26, 2016, 07:01:15 AM
Here is a vid showing the motor moving, midway through I move the camera to the motor and if you look closely on the driven pulley you can see the pulley moving rapidly back and forth, the grub screw holding the pulley in place gives an indication of how fast it is moving.

https://www.youtube.com/watch?v=0mKL5_zVqk8
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 26, 2016, 08:19:21 AM
Hiya

absolutely must have a dead-band in there, mine is +/- 1v - does not seem much but should equate to about 0.5-1mm height.

Don't forget that when re-using code from one plat thickness to another, the speed will vary but the voltage will too.

THC is a compromise it seems, you can have one that will cut corrugated steel sheet but not work too well on fine detail or like mine it will work ok on most jobs as long as the plate does not warp too much - if cutting near the edge the waste can buckle upwards and the torch will follow the waste :) I also have a tip-saver in circuit that detects sharp rises in voltage and locks the down motion out as it thinks the tip has dived into a gap or kerf, then there is Mach Anti-Dive as well which is velocity based i recall.
Title: Re: Physical buttons for plasma
Post by: Hood on November 26, 2016, 02:05:51 PM
Thanks, I would have thought deadband was needed as well but miniTHC doesn't have it :(

Yes understood regards thickness feeds and volts, same with materials.

The miniTHC seemed very quick at following once I got it half working with altering the accel and Velocity but as said it trips the servo drive after a bit, having a deadband would I am sure cure this so hopefully Denis will be able to do something there, we will see.

There is an AntiDive setting in the miniTHC which I presume is similar to your Tip-saver function, it seems to work well even though I have just set mid range and not messed with it.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 26, 2016, 02:32:22 PM
Seems odd they left out a dead-band, hopefully they can add one.

Maybe steppers are more tolerant of non-stop rapid moves than servos?
Title: Re: Physical buttons for plasma
Post by: Hood on November 26, 2016, 02:56:02 PM
Yes, said it was in their previous THC but they removed it from this one and no problems until now. Maybe most are using steppers and maybe servos are more prone to problems, don't know. Having said that servos  are used on machines that do 3d stuff so for things like photo engraving they do thousands of sharp up/down movements  and no problems.
Maybe I do just need to increase the servo size or maybe even reducing the gearing or having a larger pitch ballscrew would help.
Just don't really want to have to spend more money and time converting if something as simple as deadband would solve the issue.
I am thinking of testing out the internal THC of the CSMIO, only problem is the voltage divider is 50:1 and 20:1 would likely work better for the CSMIO.

I ran a test today cutting some alu, same code as before, 200mm long and 20mm wide rectangular path but this time I angled it at 45 degrees, the THC took it in its stride and that was at 4m/min, so it does handle things well.
Title: Re: Physical buttons for plasma
Post by: mc on November 26, 2016, 06:59:41 PM
I would expect a servo to handle those kinds of moves, if tuned well. Could it be a case of the short/sharp moves, combined with a bit instability in the tuning causing the problem?

Could you try reducing the max current/acceleration?
You obviously don't want to reduce it too much that it's not fast enough to respond, but dropping it slightly might be enough to take the edge of the moves which are causing the heating.

Title: Re: Physical buttons for plasma
Post by: Hood on November 26, 2016, 08:08:19 PM
It could well be the tuning, don't even recall when I did it, could have been before everything was fitted fully.

The servo is small so it maybe does need an upgrade but it did seem to be handling things nicely. There were some on eBay a while back and I was going to buy a couple as they were cheapish £40 or so but decided I wouldn't bother ::)
Title: Re: Physical buttons for plasma
Post by: Hood on November 27, 2016, 03:38:12 PM
Had a look at the tuning today and it was pretty good but I saw the Low Pass Filter was set very low, not sure why. Anyway I upped it to the default value and things were better but it was still tripping out after a while of running a test programme I made. Loosened the tuning a wee bit and I was able to run the test programme for over an hour so I reckon it should be fine for the moment.
 The motor does get hot but not enough to fault the drive it seems.

I found a motor on eBay that is one size up from the one I have, not too a bad price considering it also has a 5:1 Alpha gearbox on it so I decided to buy it.
Not sure how I will fit it yet, it is a direct replacement for the one I have if I decide to keep the belts or I may alter things and do away with the belts and use the gearbox instead.

Anyway here is it cutting 10mm steel, same code that it was tripping out the last day after about 2/3 of the way round.
https://www.youtube.com/watch?v=xgbLEXSUuSk
Also a couple of pics of the cut.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 27, 2016, 04:24:25 PM
Some nice looking cuts there, it really begs for a dead-band setting though ;)

Title: Re: Physical buttons for plasma
Post by: mc on November 27, 2016, 06:00:17 PM
The problem is, if it's the continual movement that was overheating the motor, then the same will likely happen with a larger motor.

It'll be a case of striking the balance between moving too much that the motor overheats, and moving too slowly the torch height doesn't respond quick enough.
Title: Re: Physical buttons for plasma
Post by: Hood on November 27, 2016, 06:20:13 PM
Some nice looking cuts there, it really begs for a dead-band setting though ;)


I am thinking that if the CSMIO didn't used the accel from motor tuning then  the THC wouldn't be moving so much but sadly it does so I will just have to see what Denis or CS-Lab can come up with.

The problem is, if it's the continual movement that was overheating the motor, then the same will likely happen with a larger motor.

It'll be a case of striking the balance between moving too much that the motor overheats, and moving too slowly the torch height doesn't respond quick enough.

A bigger motor shouldn't have to use  as much of its available current to do the same job as the smaller motor so my thinking is that should reduce the heat.
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 28, 2016, 02:21:55 AM
What screw pitch do you have on Z?

Needs to be coarse - mine is 10mm i think.
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 03:06:17 AM
Its only 2.5
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 28, 2016, 03:26:27 AM
Forgot you are on a servo, maybe its not so critical, stepper driven ones need the coarse pitch so moves only require a step or two to complete - no acceleration/deceleration etc.

Maybe servo does not need it so coarse?
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 03:30:44 AM
I have no idea Dave but think 2.5mm pitch is about the biggest I can get on an 8mm ballscrew. The reason I have an 8mm ballscrew is it was the one that was on my wee lathes X axis where the motor came from.
I decided as the motor mount/brackets/pulleys/screw was already made up as a unit that I would just use the whole lot. Originally I had intended a bigger motor and a 10mm pitch ballscrew but it was going to be more work.
Title: Re: Physical buttons for plasma
Post by: TOTALLYRC on November 28, 2016, 03:45:49 AM
Would it be possible to change the pulley ratio?
Might be the easy way out.

Mike
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 03:52:32 AM
Was wondering that myself, it is 2:1 at the moment, not sure what I have the driven pulley bored out to but I may be able to swap around so it was 1:2 which would give me 5mm per motor rev rather than the 1.25mm it is at the moment. Whether the motor would be good enough though is another matter as it is a tiny servo, 50w if I recall.

I have also found a lead screw with 8mm lead but not sure how the friction compared to a ballscrew would play with the wee servo. Probably worth a try though as it is dirt cheap and shouldn't need much in the way of alterations.
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 04:03:29 AM
Well just ordered an 8mm lead screw and nut for the princely sum of £4.49 :D
Title: Re: Physical buttons for plasma
Post by: TOTALLYRC on November 28, 2016, 04:06:33 AM
If the Z is dithering up and down that much, isn't there a setting to limit the Z travel? I just did my first CNC plasma work so I am a newbie at this but the one I worked on had all kinds of settings on the screen for THC control. It also wasn't hunting much in the Z. We were cutting at 127 ipm on ~18ga steel which you could actually see warping as we cut and it followed along with out too much drama. It was a stepper motor on the Z with a fairly fine pitch screw.

The system I setup was this one; http://www.vitalsystem.com/portal/cnc/motion/plasma.php (http://www.vitalsystem.com/portal/cnc/motion/plasma.php)

See the screen shot for all of the THC options.


Mike.

P.S. Still suffering from PLASMA envy!!!!!
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 04:50:53 AM
No settings for deadband in this THC but from what I can gather, including talking to someone else who makes THC's, is deadband should not be needed nowadays due to the processing power of modern THC's.
 The problem seems to be mainly caused by the way the CSMIO does THC movements, unlike Mach and most other motion controller it adheres to the accel in Machs motor tuning for THC moves. That sounds like the sensible thing to do but it is actually looking like it is not.
 
The CSMIO internal THC does have deadband but I have not used that due to my voltage divider being 50:1 where it would be better 20:1 with the CSMIO.

Title: Re: Physical buttons for plasma
Post by: TOTALLYRC on November 28, 2016, 05:32:35 AM
If you don't adhere to the motor tuning, won't it just fault out the servo drive anyway? If not, crank up the motor tuning!


Mike
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 12:36:03 PM
If you don't adhere to the motor tuning, won't it just fault out the servo drive anyway? If not, crank up the motor tuning!


Mike

I think it is because the movements during THC are small that the infinite accel doesn't affect it too badly where as cranking the accel up in motor tuning would affect all motion.

Anyway looked at the pulleys today and they were both bored out to 8mm so it was a relatively easy swap, had to machine a plate that held the motor on a wee bit but that was all.
After re-tuning the motor it seemed to be fine at the previous settings which I was quite surprised at as it is a tiny servo  and I was basically quartering the available torque compared to previously.
Here are a couple of vids, first is it cutting and as hopefully can be seen the pulley is not moving nearly so much now and thus the motor as well. The second is a view of the THC control panel and Mach itself, you can just about see the arrows for up/dn changing but the camera is not the best :D

https://www.youtube.com/watch?v=EmYRA_cd-0o

https://www.youtube.com/watch?v=Vh6rrtxSTpY
Title: Re: Physical buttons for plasma
Post by: TOTALLYRC on November 28, 2016, 01:06:52 PM
Looks like you are making progress.

Mike
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 01:09:38 PM
Yes, big difference on all fronts from my initial failures :D

Still have to get this better but the biggy is getting the M31 macro to work correctly every time, it is still dodgy, probably something to do with my VB skills but also I am thinking maybe the wee computer. Just building and setting up another at the moment so hopefully will get a chance to test that theory out tomorrow.

Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 28, 2016, 01:37:40 PM
Looking good :)
Title: Re: Physical buttons for plasma
Post by: Hood on November 28, 2016, 04:40:03 PM
Also found the square edge the opposite side this time :D
Looked at the swirl ring and it can fit either way so I will have to take a note and make sure I replace the same direction :D
Title: Re: Physical buttons for plasma
Post by: Hood on November 29, 2016, 05:40:16 AM
THC working exactly as it should thanks to info received from a guy called Ian who knows one or two things about Plasma :)

THC Speed % was the answer, turning it down to 50% seemed the best for my servo.
Here is a vid of it cutting 10mm steel plate, 200mm x 10mm at a rate of 800mm/min.

https://www.youtube.com/watch?v=TU2Ftfxosww

Here is it doing the same but with the plate raised at about 3 degress so that it raises 10mm over the 200mm cut length.

https://www.youtube.com/watch?v=8efACIOWgPA


So big thanks to Ian :)

Now I just have to get the better of the M31 macro issue.
Hood
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 29, 2016, 06:23:59 AM
Very nice, I think my one is at about 20% but it does make a massive difference

:)
Title: Re: Physical buttons for plasma
Post by: Hood on November 29, 2016, 07:17:38 AM
Happy with the cuts now as well, here is the 10mm steel I was cutting in the above vids.
Only problem is I have chopped up a load of material decent getting it to this stage :D
Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 29, 2016, 08:01:16 AM
I know the feeling with the waste, I chewed through a heap of metal and consumables on my learning curve, no way round it really, comes to a stage where you just have to push the start button and see what happens :)

I can usually get a new material/thickness dialled in with one or two straight cuts now.
Title: Re: Physical buttons for plasma
Post by: Hood on November 29, 2016, 08:13:25 AM
Yes that will be something I will have to learn, get a notebok and write down what I find best.
Good thing about the miniTHC is the pot on it can easily be adjusted on the fly to increase/decrease the voltage.
How do you set your voltage, via the S word in your code?
Title: Re: Physical buttons for plasma
Post by: Chaoticone on November 29, 2016, 08:48:48 AM
Looking good Hood! I bet you will use that thing an awful lot. Will be handy as a side pocket for you. I love seeing you get/make tools that makes things go better for you.

Is the smoke getting out quick enough? Looks like it is in the videos.  :)  Just try not to breath any of that stuff.
Title: Re: Physical buttons for plasma
Post by: Hood on November 29, 2016, 09:10:47 AM
Looking good Hood! I bet you will use that thing an awful lot. Will be handy as a side pocket for you. I love seeing you get/make tools that makes things go better for you.

Is the smoke getting out quick enough? Looks like it is in the videos.  :)  Just try not to breath any of that stuff.

Yes, going to be the most used machine here I think :)

I need to get some fans and duct work, I built 3 trays and I was going to use water but I reckon if I have a fan for each section it will be fine, will buy one first and see and if it works I may try joining the second section to the same fan and see if it will work for two sections and if it does I will try the third. If it is a failure of one fan on more than one section then I will get one for each. If the fans are a failure then I will revert to the water.

Bloody typical, no problems with the M31 at all on all my tests today then someone comes in and wants to see it running and failure after failure LOL Eventually got it to work and it worked fine for the 3 tests I did. Will have to try and get a chance today to swap the computers and see if the wee comp is the issue, hopefully it is.

Title: Re: Physical buttons for plasma
Post by: Davek0974 on November 29, 2016, 12:44:44 PM
Yes, the details are set in sheet-cam, passed to the machine as the S word then i also have up/down nudge buttons on-screen.
Title: Re: Physical buttons for plasma
Post by: Hood on November 30, 2016, 02:52:44 AM
Ah yes of course, spindle override would just work the same.
Title: Re: Physical buttons for plasma
Post by: luisandres55 on April 23, 2017, 07:10:42 PM
HOLA
ALGUNO DE USTEDES ME PODRÍA DECIR , QUE CARACTERÍSTICAS LE PONGO A MACH3, PARA PODER CORTAR ACERO INOXIDABLE, ALUMINIO Y CHAPA, SEGÚN SU ESPESOR, Y VELOCIDAD?
DESDE YA MUCHAS GRACIAS
SALUDOS


Hello,
Some of you could say, what characteristics do I put to Mach3 to be able to cut Stainless Steel, Aluminium and Plate, according to it’s thickness and speed ?
From already thank you very much.
Regards.


edit - translation added.