Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Davek0974 on February 13, 2016, 04:16:42 AM

Title: Educational Sources???
Post by: Davek0974 on February 13, 2016, 04:16:42 AM
Hi all,

Having embarked on building a CNC router/mill of around 400x500mm size, and so far only having knowledge of 2d CNC in plasma cutting I realise I have a pretty large gap in my knowledge base  :D

With all you multi-talented types on here, can anyone point me to a resource that would help bridge the gap between CNC plasma cutting and CNC milling - I have no idea about cutter compensation, homing (plasma is always top of material), cutter length, tool height setting, tool numbers etc.

Some sort of CNC mill primer??

Youtube is loaded but mostly not relevant stuff or presumes knowledge already.


Thanks
Title: Re: Educational Sources???
Post by: RICH on February 13, 2016, 04:45:14 AM
Purchase the book "CNC PROGRAMMING HANDBOOK by Peter Smid".

RICH
Title: Re: Educational Sources???
Post by: Davek0974 on February 13, 2016, 06:52:19 AM
Ok, found it, little expensive but sounds good, will order a copy.
Title: Re: Educational Sources???
Post by: Tweakie.CNC on February 13, 2016, 07:53:07 AM
You may also like to spend some time looking at the CNC Cookbook site   http://www.cnccookbook.com/

Tweakie.
Title: Re: Educational Sources???
Post by: Davek0974 on February 13, 2016, 08:02:16 AM
Thanks, bookmarked ;)
Title: Re: Educational Sources???
Post by: BR549 on February 13, 2016, 11:46:30 AM
There is a decent reference manual on Gcode right here on this site.  http://www.machsupport.com/forum/index.php/topic,24580.0.html

Several of us have discussed building a ref library here on teh site BUT that can get complicated.  At best I think we can only put together  a list of LINKS to the works.

The problems with that is LINKS come and go so some of the references may disappear over time.
Title: Re: Educational Sources???
Post by: Davek0974 on February 13, 2016, 11:50:59 AM
Thanks
 :)
Title: Re: Educational Sources???
Post by: Davek0974 on February 14, 2016, 10:13:36 AM
Whats the recommended CAM software for mini-mills/routers etc?

Free would be nice but i don't mind paying for really good stuff.

I have got a trial of G-Wizard which looks useful, very complicated but useful, pity about the subscription cost, I prefer a one-off purchase.
Title: Re: Educational Sources???
Post by: mc on February 14, 2016, 10:42:52 AM
I've used CamBam a good bit. You get 30 completely unlimited uses before you have to buy a license, and even then it's not that expensive considering what it can do.

Although I am looking at moving to BobCad, however it's much more expensive, and only really worth it if you need the extra features, but I'd say get experience using something free/cheaper first.

I personally have a multi-PC HSMAdvisor license, although I think they've since dropped that option. They also have a free web-based calculator called FSWizard, which covers all the basics.
Title: Re: Educational Sources???
Post by: ger21 on February 14, 2016, 11:07:14 AM
For routers, the most popular software is V Carve Pro, but it's not inexpensive. I wouldn't go anywhere near BobCAD.
Take a loot at Fusion 360. Free for hobbbyists, and rapidly gaining in popularity. And it's a full CAD and CAM package.
Title: Re: Educational Sources???
Post by: mc on February 14, 2016, 11:23:11 AM
I forgot about Fusion 360. It's pretty good, however I'm not risking my commercial drawings floating around in their cloud tied up in their proprietary format. I'll stick to having my own DXF/STL files floating around in my own cloud.

Gerry, any particular reason to avoid BobCAD?
It seems to tick all the boxes I'm looking for, mainly HSM toolpaths with a reasonable work flow.
Title: Re: Educational Sources???
Post by: fixittt on February 14, 2016, 11:30:03 AM
you cad/cam packages should be geared to what you want/hope to achieve.  
Want to do wood engravings then dont look at Visualmill, ect.

With a router and vectric products, you really cant go wrong.  I have aspire and really love the software.  powerful, lots of tutorials ect.
HSM express and fusion 360 are amazingly powerful software packages.  but they can overwhelming for somebody new that just wants get the ball rolling.  But also do not dismiss the wizards in mach3.  They can help make a part by using multiply operations.

Speeds/feeds Depth of cut ect is going to be your biggest hurdle.  G WIZARD.  Its a speeds and feeds calculator that will get you in the ballpark 90% of the time.

Welcome to the wonderful world of CNC.  Wear a hat at all times so you cannot pull your hair out.  This crap aint easy!
Title: Re: Educational Sources???
Post by: Davek0974 on February 14, 2016, 11:30:54 AM
Just installed Fusion360, might need a college course to fathom it out but it looks good, I do have a very serious dislike for anything to do with cloud though, can't find anything to do with CAM in it though??

Will keep looking.
Title: Re: Educational Sources???
Post by: fixittt on February 14, 2016, 11:31:52 AM
DO NOT GET ON BABCADS LIST!!!!!

bobcad can be talked down alot on price, but god man, they will never leave you alone!!!!!  Sales holes will call, email ect to get you to spend more money.  A friend of mine has purchased it years ago, and they still call him every week.

Title: Re: Educational Sources???
Post by: ger21 on February 14, 2016, 11:37:23 AM
You can export your Fusion models in a variety of formats if your paranoid.

As for BobCAD, there are 10 years of posts on various forums that are enough to scare anyone away.
To be fair, I've heard from serious users that it does offer more bang for the buck than most other CAM packages.

Their sales tactics are questionable at best. They'll sell the same package to one person for $500 and sell it to the next one for $1500. The longer you want, and can tolerate their sales calls, the cheaper you'll get it for.
I've read many posts from people that find out after their purchase that they didn't get modules that they thought were included in the price.

It's probably the least intuitive CAD/CAM package out there.

Their policy is to only provide bug fixes to customers paying for annual support. I read a lot about some serious bugs that often don't get fixed until the next version.

Just spend some time reading the forums about BobCAD complaints. You rarely see post like this about other packages, but there are hundreds of unhappy BobCAD users out there.
Title: Re: Educational Sources???
Post by: Davek0974 on February 14, 2016, 11:54:50 AM
Oh bum, looks like i've gone and run into another minefield :(

I think I need 2.5D, I'm ok with basic 2D and can generate 3D .stl files with an app called OpenScad which i use for the 3D printer. In reality I'm probably not too far off in terms of stuff in the brain, it just feels like I've been taken from the paddling pool and thrown into the olympic pool but I've still got my armbands on ;)

3D printing is pretty easy by comparison, it only has one tool - a fixed diameter nozzle, fixed layer height and once you get it to work, it works fine. No offsets etc - its additive so all jobs start in the centre of the bed - no workpiece :)

I guess building a multi-purpose machine means I have multiple headaches now - carving, routing, milling, etc :(
Title: Re: Educational Sources???
Post by: mc on February 14, 2016, 12:03:35 PM
Thanks Gerry. I've seen the various posts, but BobCAD does seem to offer good bang for buck, and ticks the boxes I'd like.

I might have another play with Fusion 360, but last time I tried it, the export capabilities were very poor. Some parts I make have quite a bit of design time tied up in them, and I really don't want to be locked into any specific software.


Dave, everything CNC is a minefield. You've just got to pick how expensive a minefield you like to play in :-)
Title: Re: Educational Sources???
Post by: rcaffin on February 15, 2016, 05:23:17 AM
It all depends on what you want to do with your machine. Really!

I use Autosketch for 2D drawings, and taught myself to write g-code. My programs are more complex and far powerful, and yet MUCH smaller, as a result. That's for semi-production machining too.

Cheers
Roger
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 07:29:36 AM
Well i guess I want to take a 2D cad drawing, convert to 3D then throw at the router/mill to have it hacked out of whatever.

Now I know i need a CAM stage in there somewhere to create the code.

I am way behind writing any code myself, very minor experience only and that is 2D stuff on the plasma.

I managed to find the CAM stuff in Fusion 360 so thats a start i guess :)
Title: Re: Educational Sources???
Post by: ger21 on February 15, 2016, 07:34:21 AM
In most cases, you don't need to convert the 2D drawing to 3D.
In 20 years of programming and running an industrial CNC router, I've only needed a 3D model about 4 times. Everything else is done with 2D drawings.
Since I just started using Fusion 360, and haven't learned the CAM part yet, I've been exporting 2D drawings from Fusion and creating my g-code from them.
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 08:09:34 AM
Sounds good, now i look at it, I can see it really is a 2d form but with a known depth so i guess thats why they call it 2.5D ??

I have 2D cad ok, I use a couple of apps for that and can do all i need, they export DXF files.

What do i pass them to for the CAM part?

I have fusion360 setup and I see its free for hobbyists so thats good. Will that be the app to take the the DXF, add tool sizes etc and spit out g-code??

My 2D workflow is CAD -> SheetCam -> Mach3 Plasma

My 3D printer is CAD -> Slic3r -> Printer (proprietary system but runs G-code)

So 2.5D will be CAD -> ???? -> Mach3 Mill
Title: Re: Educational Sources???
Post by: ger21 on February 15, 2016, 08:19:53 AM
If you already use SheetCAM, then you don't need anything else.
CAD -> SheetCAM -> Mach3
Title: Re: Educational Sources???
Post by: BR549 on February 15, 2016, 08:55:39 AM
2.5 or 3d ??  Well that dep[ends on what you entend to cut on your machine (;-). If it is just parts and pieces then 2.5 works just fine . IF you plan on doing any carvings,etc then you will need 3d.

For the most part on 2.5  Scam will get you by.

(;-) TP
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 09:24:50 AM
If you already use SheetCAM, then you don't need anything else.
CAD -> SheetCAM -> Mach3

BOY, AM I SOME SORT OF BLINKERED IDIOT !

I love sheetcam, quite good at messing with that from my plasma table, I can honestly say I never knew it anything other than sheet cam as in plasma etc !!!

Even though it shows a milling tool as a splash-screen!

I have my install set for flame/jet only so all the goodies are hidden away from me - just turned it on and already have some code ready for armchair scrutiny :)

Sheetcam and a speed/feed calc will do 90% of what i need to start with - brilliant.

Thanks for poking me with the sharp stick :)

Question - do i need to change post processors ????
Title: Re: Educational Sources???
Post by: BR549 on February 15, 2016, 09:55:05 AM
Yes you do need to change your Post to reflect what you are doing with Scam. AND if you had the Feed/Speeds plugin for Scam then you would be set ?  :o 8) ;D

(;-) TP
Title: Re: Educational Sources???
Post by: BR549 on February 15, 2016, 10:03:09 AM
Actually that is an OLD plugin. I need to redo it like I did one for UCCNC.

(;-)
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 10:39:33 AM
Are these plugins still available?

want, want, want........:)

Is there a good post? I see I have one called "Mach3" or various other machine names.

Been messing with my Scam and it all makes sense when you get to an app your'e familiar with :)

Specific question,
I have one job in mind that is ally, 3mm thick and has some 3mm dia holes in it, if I had say a 2mm single flute cutter in, would i change to a drill or just plunge-cut with the mill and open out to 3mm in a circular pass??
Title: Re: Educational Sources???
Post by: BR549 on February 15, 2016, 11:45:18 AM
You could do it ether way but teh drill is designed to do a controlled plunge cut, straight down. With a single flute cutter cutting ALUM they do not do a straight plunge well because of only having 1 flute. So in that case you do a ramped spiral cut in a circle that way everything moves in a very controlled motion for a single flute cutter in ALUM. 

Cutting Alum at router spindle speeds can be a challenge because at teh spindle speeds of a router your feedrate will have to be very high .

For your MP ( Multi purpose) machine I would consider a Spindle with a seperate motor and a multi speed pulley setup. That way you can gear it for the best speed for each type of cutting.   You copuld have Super high for engraving, High for router and lower for metal.

Just a thought, (;-) TP
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 12:57:45 PM
Thanks again TP,

Its all falling slowly into place now, once that happens i can get a grip on things ;)

I will save the multi speed head for an upgrade, the spindle I have coming is 2.2kw and supposed to run from 8,000 to 24,000rpm

From what speed/feed calc i have dabbled with so far (not many) the feed rates seem fine.

Any recommendations on a Scam post??
Title: Re: Educational Sources???
Post by: BR549 on February 15, 2016, 01:17:16 PM
Standard Mach3 post ( with arcs) for 3 axis  (;-)

(;-) TP
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 02:52:03 PM
Great stuff, found out how to do a ramped spiral cut, works well in simulation anyway.

Also found the "sharpen corners" features, will need that for a job in mind, again it looks ideal for my needs.

Nice, and I never even knew it could do it :)
Title: Re: Educational Sources???
Post by: rcaffin on February 15, 2016, 03:32:41 PM
The invoice will follow ...
Cheers
Roger
Title: Re: Educational Sources???
Post by: Davek0974 on February 15, 2016, 03:45:00 PM
This place is an absolute gold mine of information and helpful people, hard to find these days.


Thanks to all for the help so far.
Title: Re: Educational Sources???
Post by: joeaverage on February 16, 2016, 02:26:41 AM
hi davek0974,
sounds like youre sorted with software for the moment. I tried Fusion and it wasn't bad, the CAM is pretty seemless with the CAD. In the end I found the lack of 'determinism'
let it down. No doubt the programers of Fusion think their software is intuitive it can also be hard to control both CAD and CAM. It is free tho....
I went back to Mastercam which is not and can be cussed as hell at times but dependable and configurable.
I have a smaller spindle, 750W and use it a lot for PCB's and some aluminium. It is NOT up to steel. All the high speed spindles have poor torque at low speeds and if the spindle
stalls you have yet another broken tool. Even with 1/4" tools I try to get the speed down to 5000 rpm to save the tool from burning up but the wee spindle has very low
torque at that speed and has cost me a number of tools as a result.
So much so that I bought a second hand 2.8kW servo off Ebay with 12Nm rated and 48Nm overload at 3000rpm. Imagined I was going to run it with a sensorless vector
type VFD. That proved to be a mistake. My own experience and reports on CNCzone suggest sensorless vector drives work but well short of that than can be achieved by
a genuine servodrive. Theres the rub, plenty of good servos cheap but a mating drive is bloody expensive. I have spent the last two months building my own drive from
scratch and been a hell of a learnnig curve! Well on track tho...
If you want to cut metal, steel or tougher you will need a spindle capable of low speeds with plenty of torque, suggests an induction motor with gear or belt reduction
unless you can spend BIG bucks on a direct drive servo or async drive.
Good luck, keep posting, it great to hear how folks progress, and CNC addicts them!!!!
Craig
Title: Re: Educational Sources???
Post by: Davek0974 on February 16, 2016, 03:37:22 AM
Thanks, I'm mostly heading for small cutters in aluminium so will see how it plays when i get going.

Specific questions related to say 3mm aluminium cutting....

Holding tabs - would you use these on small internal features like holes etc, say 10mm x 20mm cutout or just let the scrap part loose?

Holding tabs - outside edge/final cut how thick should they be, I am guessing at maybe 0.25mm based on my experiences on the manual mill?

Spoil boards - when doing aluminium, what would you place underneath to cut into presuming you want full depth cutting with tabs?

Z Zero - Say i have a 2mm endmill in the collet, how do you set the surface zero on a router/mill?

Thanks
Title: Re: Educational Sources???
Post by: ger21 on February 16, 2016, 07:09:56 AM

Z Zero - Say i have a 2mm endmill in the collet, how do you set the surface zero on a router/mill?


Auto Zero macro.
Title: Re: Educational Sources???
Post by: Davek0974 on February 16, 2016, 07:32:22 AM
Ah, but what does it use for height sensing??
Title: Re: Educational Sources???
Post by: ger21 on February 16, 2016, 07:41:52 AM
A simple plate wired to an input.
Title: Re: Educational Sources???
Post by: Davek0974 on February 16, 2016, 08:04:32 AM
Sounds good,

I gather thats a plate of known thickness which is allowed for in the routine pretty much like the switch offset in plasma cutting IHS?

Something like single-sided PCB - insulated from the bed?
Title: Re: Educational Sources???
Post by: ger21 on February 16, 2016, 08:14:42 AM
Yes, if your working with a mill. For a router, I just use a piece of aluminum.
Title: Re: Educational Sources???
Post by: joeaverage on February 17, 2016, 04:07:54 AM
Hi,
I try to have say an internal scrap part stay fixed when milling aluminium. It sort of comes down to 'evacuating' chips, when slotting
or any internal milling evacuating chips is about the most significant thing you can do to ensure a good result, failure to do so
invites 'built up edge' and usually disaster for the part and the tool.
When milling an external contour or surface its less critical, usually compressed air or coolant flow is sufficient to clear the chips and
larger scrap bits tumble away from the tool.
Most of the parts I make are milled out of billet so the part stays attached to the parent material which  I then part off with a hacksaw
or a 125mm cutting disc with a mandrel which fits into the spindle. Works well IF and ONLY IF the spindle is trammed to the table, I had
some sticky moments learning that rule!

Craig