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Mach Discussion => General Mach Discussion => Topic started by: wil on November 21, 2007, 06:15:57 AM

Title: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 21, 2007, 06:15:57 AM
Hi everyone,
My firts post here but I have been reading and learning a great deal here for a while.
Mach3 is absolutely superb and it`s continued development is taking the software to amazing new heights,
so congrats for that.

My project is a bit unusual,
I have built a 3 axis system to control and freeze a very fine jet of filtered water in the hope of producing
3D mold cavities made of Ice. Like other rapid prototyping systems this is done by building up 2D layers.
At the moment my 0.005" nozzle orifice is giving far too much flow and this means there is too great a volume
to properly freeze on contact with an already frozen surface. So I`m still working on fixing this.

This leads me onto my call for help.
When the machine does an axis change of direction, for example imagine a simple square border, the nozzle keeps pumping for the duration of the axis change at each corner, resulting in an unwanted `blob`at that point.
I have tried the following code :  (Units are in mm)

G1X0Y0
Z0
M08
G1X50
Y50
X0
Y0
M09
G0Z10(END)


This was slightly improved by adding nozzle On/Off commands
G1X0Y0
Z0
X50M08
M09
Y50M08
M09
X0M08
M09
Y0M08
M09
G0Z10(END)

What I am hoping is that there is a way to manipulate the way Mach3 sends the signal.
Imagine if when Mach3 reads ahead it could control the timing of the signal. So lets say
if it sees an M9 command coming up it will activate the command a few milli-seconds sooner
than it would normally. In other words I could control the on/off flow of water during pauses
in direction change.
If anyone can fathom what I`m on about and offer any help it would be greatly appreciated.
I`m not sure if a VB script or perhaps Brains could do the job.

BTW I have Mach setup on `Exact Stop` as I`m not sure about using Constant Velocity.
CV Distance and CV Feedrate ?

Regards
Wil
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 21, 2007, 06:45:46 AM
Welcome Will,
    Have you tried it in CV mode? I would think that would be the best path to try first. It doesn't sound like you have any tool load. With motors strong enough to acheive High accel. rates, I think it will do good. You could try it and see. Try it in CV mode. Don't worry about any of the settings, leave them all at the default values.

Brett
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 21, 2007, 07:49:09 AM
thanks Brett I`ll give it more of a try tonight.
My initial attempt showed very rounded corners under CV mode, as I said I`m not too sure
about changing the settings, my default is CV distance 180 and feedrate +1.0 which I`m taking
to mean just that, ie feed is the same as program feed along straight paths and moving around corners.

Any chance you could explain the cv distance please.
At the moment I`m running my motors at full speed (I think so anyway) and getting around 60 IPM
With a bit of luck, once I iron out all the problems this will be my build speed which would be awesome.

Lovin Mach3 I even managed a screen change with the Mach3screen prog. Screen 4 is great also
but at times I had some problems being able to edit the buttons etc.

here`s a pic of my latest effort, you`ll notice I have added the MDI line to the main program page
and also done away with tool offsets and anything else relating to spindle work.
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 21, 2007, 08:32:49 AM
Good job on the screen Will,
    You can do a search on cv and come up with lots of post explaining it. If your corners are rounding bad, I assum you need to be able to accel at a much higher rate. For what you are doing, you need it to be almost instant, nothing to wide open. You might want to try some test of tuning your max speed down and your accel up in motortuning to help with the rounded corners. For you set up you will need insane accel rates I think to pull it off. Great idea though and attainable I think. Might require stronger motors though. Look at teh rounded corners like this, a Corvette VS a cube van in the slolum. A big motor and good suspension, in this case a rigid frame, mounts, etc. will get around the corners much faster. I'm going to retrofit another mill soon I hope. I will be using 1KW med. inertia servos. In the Visual sizer, I should be able to achieve 750IPM rapids with accels of .05 seconds.

Brett
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 21, 2007, 09:08:53 AM
Ok great, I`ll look at the tuning specs also, I calibrated my axes using mounted digital vernier scales and then by trial and
error I ramped up the velocity as high as I could and adjusted the Acceleration to eliminate any stalling. I`ll post a pic to show what I have later on. ( at work atm)
That Visual sizer program looks interesting. Am I right in thinking that is a seperate `bench` test and you are not able to use your mach3 motor tuning settings ?

WoW - 750IPM rapids with accels of .05 seconds that`d be soming else
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 21, 2007, 09:22:56 AM
Yup, it is a stand alone program. It is just to help pick the right servo for the application. It is a free download. Cooperhill technologies are the arthurs. You can find it at automation direct, about half way down on the home page, servos link. It will take you to a sure servo page with a link to software or downloads, can't remember.

Brett
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: vmax549 on November 21, 2007, 10:38:41 AM
WIll I beieve a part of your problem is that when changing directions you are covering part of the area twice. We worked with some painting apps that had the same problem. The solution was to reroute your paths. I don't believe that mach cannot  control the m8/m9 that precisely.

SO in your path try moving past the intended turn point and then make a loop outside of the spray path after you have cleared the endpoint. Then come at the cross direction head on turning the spray off as you clear the endpoint and back on at the point where you have cross back over the previous endpoint. That will help prevent overlapping the spray.

You will need to go to a "fine"  mister nozzle to be able to quick freeze the water on the form . Once you have the correct mist pattern the overlapping is NOT that much of a problem  as there is no extra water flow to create the buildup or start to thaw the previos layer.

ALSO ART has just added a time delay to the M8 function. I know you don't think that would work BUT it will give you something that allows you to adjust the timing a bit. If you can adjust the delay you can plan ahead from when it would normally start then adjust the delay tt restart as needed. You just have to plan for the delay in planning your path.

Just a thought,TP
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 21, 2007, 11:42:14 AM
Thanks very much for your great comments.
I must say I hadn`t thought on trying to create a `mist spray` I have been hell bent on tryin to have the smallest possible flow from the nozzle, I can regulate the pressure and when going down to virtually zero pressure the flow takes on a life of it`s own , it comes out of the nozzle at any angle it chooses which is obviously no good.
And thanks for the info on going past the endpoint to prevent overlapping.

I have been looking at buying a Rapid prototyping software called VisCam (http://www.marcam.de/Eng/default.htm)  which has user configurable
post processors to suit most makes of RP machines and techniques used.
I`ll be able to import an STL solid model and set the slice parameters etc
and post it as G Code straight into MACH3, how cool is that.
When I think I am ready I will download their 30 day trial and give it a go.

Ok many tnx again, I`ll lookout for the m8/m9 delay function in mach


regards
wil
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: jimpinder on November 21, 2007, 11:48:25 AM
To get a uniform application you really need the water pump to be variable rate. I would then tie this to the feedrate. If the feedrate slows, the pump slows, if it stops, it stops etc. It is clear from Mach3 that the feedrate is constantly calculated already - and is therefore probably readily available on a DRO.

You could easily output this to the control for the pump.

Such an application would also be applicable to the paint spraying problem.

Jim
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: vmax549 on November 21, 2007, 11:55:12 AM
Jim HUM you could tie the pump output into a servo control valve and run the servo valvet from an axis that way you could  sync the two together.

BUT the problem is when you vary pressure/flow  the MIST pattern becomes unpredictable at times.

Will you can find the FINE misters from a good garden or greenhouse supply company. I have used them in the greenhouse and they can put out a very fine MIST and i believe that is what you are going to need.

(;-) TP
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 21, 2007, 02:24:22 PM
Hi Brett
here are my motor screens.  It`s a long story but i`ve ended up with 3 different stepper motors.
X Axis has a 3.5mm pitch ballscrew, Y is a 5mm pitch and Z is 2mm

jimpinder thanks for your input, what I`m using is a reverse osmosis filtration unit which basically pumps the filtered water
into a pressure tank, on full flow my gauge shows a maximum output of 1.8 bar (around 24 psi) unless I had some sort of
pinch valve I`m not sure how I could control the flow using Mach3. My nozzle valve is a car`s fuel injector which is just a
thru flow open/close solenoid valve controlled by M8/M9 signals in Mach3.

vmax tnx I`ll look into the misters. I`m looking for the finest possible flow to get the best finish resolution.
I`m just a bit worried that any sort of high pressure will cause the layer to splatter as it lands.
I can buy a 0.05mm nozzle to suit my existing setup. The 0.127mm nozzle I have now produces a frozen line width of around
0.8 mm or so, which is too course.  This line width might be a lot finer if the build speed were a lot faster perhaps.

Still a long way off my target  ;D
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Whacko on November 23, 2007, 12:36:18 PM
I should propably not ask this question, but this project of yours is really got me inquisitive, what are you modeling? I saw some info about the Ice Hotel and the patrons were using ice glasses and mugs for beverage consumption. That should keep a frosty mighty cold or what!

Whacko for cold beer
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Whacko on November 23, 2007, 12:40:56 PM
Say, could you adapt an airbrush but instead of paint, use water. I was thinking of using this as a marking device for a flatbed application. There is many ways to control the flow in Mach3. A bit off the topic, check out this link, http://fabathome.org

Whacko
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 23, 2007, 02:27:19 PM
Interesting isn't it Whacko?

Wil, I would guess you would need to be able to pull around 1.5Gs in your motor tuning to acheive a very clean path. I use this number only because on the simulations I mentioned earlier, that is what they were.

Brett
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Whacko on November 23, 2007, 05:09:33 PM
Yep, got to see the end product.
Wil, you could have some more solenoids in parrallel with needle valves that you preset. So you will activate the needed flow solenoid with a macro call or button/vbscript commands.
Just a thought, don't mind me if I'm way off! It's just that when I hear the word Ice, my mind goes wandering. Some Bourbon on ice, or an "ice" cold beer...

Whacko
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 24, 2007, 09:12:00 AM
howdy Whacko, tnx for your input.
I have actually built the fab@home electronics setup and got it working on my machine.
While they have done an excelent job on their project the build speeds are far too slow for what I want,
the max speed I got was 5mm per second. But really the thing that put me off fab@home was the gui
interface,I never felt I had much control, I much prefer using Gcode and Mach3.

A while back I bought a nice fine airbrush and yep of course it`s already been fully stripped down  ;D
I have the needle valve and seat ready and waiting should I decide to go down that route.
At the moment I`m trying to stick with the nozzle arrangement I have, The holder I made
for the Nozzle valve also incorporates 3 power resistors mounted in a triangular array which
provide me with a heated up air gap (between 3 to 5 deg C) as close to the nozzle end as possible
to prevent nozzle freeze.

Being a bit impatient I could`nt wait the 2 weeks or so to get the smaller .05 mm nozzle so I stuck
a bit of epoxy resin to the bottom of my .25mm nozzle I had and ground a very fine point on the
end of a drill bit, I was able to gently push this thru the back of the nozzle till it just poked thru the epoxy
and have managed to make a .035mm dia hole (measured on a shadowgraph).
So armed with this I thought great I have a much smaller dia flow it`s got to help.
Hey man the flow runs well, at full pressure I can create a water jet the thickness of a hair and shoot this
for about 200mm before the jet breaks up. In practice I want the nozzle between 3 and 5mm from the build layer,
and reduce the pressure as much as possible.
In principle the machine is working, I must just match the flow and freeze speeds to the axis speeds, and still try sort
out this problem of flow blobs during axis pauses.

I think that problem is my hardware, I cannot get more G`s out of my motors without them stalling all over the place.
And so I cannot get the table speeds I need. Perhaps the Stepmaster Driver I`m using is`nt up to the job, or maybe
just bigger and faster stepper motors would be the solution.
If I hold the nozzle in my hand and literally sweep it quickly over a frozen plate, I get a lovely thin and blob free frozen line,
just the job.........

So thats where I am ATM.

Regarding my final goal.
As a mold toolmaker I always wondered about making prototypes a lot cheaper and faster. So I came up with this Ice idea.
Our company manufactures big pump assemblies and all too often bad designing causes problems on final assembly, brackets and
castings being in the way of pipework for example.
What I`d like to do is make scaled models of each of the assembly components, these can be put together as a miniature mock-up
of a proposed build and discussed while still in the design stages of a customers order.

So I want to create molds made from Ice, and my intention is to pour/inject pourable plastic into the cavity, let the plastic harden and melt the ice away to leave the 3D component.
I tell you it`s a pleasure working with water, there are no expensive consumables like those found in other Rapid Prototype systems.

here`s a few pics of the nozzle arrangement, the flow and a crappy blobby effort
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: cjmerlin on November 24, 2007, 09:36:47 AM
Hi, Interesting projects. I dont know whether this is relevent, just an idea. If you have your flow output controlled by a soleniod (similar to how some car engine fuel injectors work) could you attach the solenoid to Mach's spindle step/direction output. By using steps you will be pulsing the soleniod with the S command and have full contol over flow.


John
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Whacko on November 24, 2007, 01:24:47 PM
Amazing! How do you stop the water from atomizing when it leaves the nozzle? I had an idea you wanted to build moulds, somehow like the lost wax method. 10 outa 10 for innovation to you Wil ! Is the expansion factor gaugeable?

As far as nozzles, have you thought of trying the nozzles you get in the High pressure waterjet cutting machines?

Whacko
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 24, 2007, 02:14:09 PM
thanks cjmerlin, that is an interesting idea. I have no clue as to step/dir or PWM so I`ll need to read up on that.
On the Ports & Pins>Spindle Setup .. the General Parameters settings, those Spin up/Spin down delays could be useful.

Actually Whacko I`m wondering if atomization would be a good thing, if the spray were to be broken in micro drops it may have better `freeze on contact` ability. I have been looking at Ultrasonics, the trouble I have is that the nozzle outlet has to be a close as poss to the solenoid valve, or you get pressure buildup and release problems and even drops forming at the nozzle tip.
In principle atomization is the same as mist (as mentioned earlier in the thread) but I cant see being able to make a nozzle produce mist within a circular area the size of .035mm dia.

Regarding expansion - the way I see it - what you spray and measure in terms of line thickness and height will determine the slice parameters you`ll end up using to get the best resolution. But yes I cannot wait to see how accurate say a 10 mm dia hole comes out and what size 10mm + - `plug` I`d have to make to fit the hole.
As you know most moulds consist of stationary or sliding cores and Icemoulds will be no different, apart from not having to slide.. hehe I can have any amount of `undercut` features and not worry how to `eject` the part. I just melt the mould away in 2 secs.
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 24, 2007, 02:46:17 PM
@ cjmerlin
yes I think PWM could be a good tool. Imagine a simplified senario as an example, a syringe. If the plunger was controlled by a stepper motor I could use PWM to slow it down on axis direction changes and have less flow at those points. When the plunger reaches the bottom of its stroke I`d have to have a limit switch that would pause the program and automatically retract the plunger which when it reaches the top of the stroke opens a valve that fills the chamber again and off the prog continues. Do you have any clues as to how to implement PWM at certain parts of a gcode program ?
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 24, 2007, 05:27:45 PM
Wil, I think a fuel injector would work good. They are designed to atomize. Cjmerlin is on to something. You can set it up as feed per rev. So you should get a really even build. You may be able to do this very easy. I will look at gecko drives and see if you can run a 12 VDC. All an injector does is get pulses, like a stepper.

Brett

Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Whacko on November 25, 2007, 03:42:54 AM
Plasma cutters use swirl in the gas to stable the arc. If you were to use a plasma torch, and a vacuum enduced draw off to water, like a spaygun, you could stop and start the action with a solenoid, and have a fine, stable mistline out of the plasma torch. Obviously a hack, the plasma won't like water too much.
You could have a stepper motor on the needle valve to control the water/air flow. Is your application in a cryo cooled vessel? If you have a low enough temperature, why not use steam? We can help you with the Mach3 implementation.

Whacko
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 26, 2007, 02:38:45 PM
Thanks guys, I appreciate your continued input.
I`m just trying to get to grips with my slow table speeds.
Brett as you can see from my motor tuning pics I am miles away from 1.5 G`s
ATM I have a 24V DC  14.6 Amp PSU for the Stepmaster driver, tommorow I`ll have the chance of borrowing
a 30V supply so I`ll see if that makes any diffs. Other wise I may need to look for bigger motors and possibly
go for individual drivers this time.

Whacko, no mate not cryo, my machine is just built in and around a bog standard desktop freezer which gets down to around -25 deg C
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: Chaoticone on November 26, 2007, 09:55:04 PM
I understand Wil. The beauty of running the water as a pwm, the speed and accel. issuse would hardly matter then.

Brett
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: cjmerlin on November 28, 2007, 02:34:51 PM
Hi All, just been away awhile so I'm missing the fun, Well there's two different things to try with this, My first I mentioned earlier was the step method where if connected to a soleniod (injector) setup means that you could give the M07/08 code at the beginning of the program and control the flow with pulses from the S word (more flow/more pulses) ie: larger S and no flow (S at 0).  This method may give a faster response than using M codes to switch the supply on and off.

The second method looks like a more complicated idea using the PWM method as I think you will need some sort of feedback for the PWM to work properly. If you are into electronics then you could sort something, maybe an encoder attached to the stepper to supply the feedback would do, then the pulse width of the PWM can be controlled using the S word.
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: wil on November 29, 2007, 04:06:31 AM
thanks cjmerlin. Yes your first method sounds great. I have found a nice looking solenoid driver http://www.rwautomation.com/products_sc5.html  that should do it. I`m not sure if my current valve driver is up to the job and is not configurable like the SC5 is. So i`m looking at that.
I still have some reservations on to how to implement the S codes within a program, it obviously pretty easy to edit the gcode for a simple rectangular path, but when I start to do more complex profile work I`d need an automated way to implement S codes. I will send an email to VisCam support to ask whats possible with their software, this can`t be an isolated problem.

Brett I appreciate what you`re saying about speed and accel but I really feel my speeds are too slow, full rapid measures around 60 inches per min, this equates to around 25 mm per sec and although I remember saying if I got a build speed of around 30mm per sec I`d be happy, well at the moment I`m feeling I need a lot more lattitude to play with, I dont want to be caught short later on in the project.
This reasoning is also coupled with the fact I do have a few mechanical issues to sort out, trouble is every now and then I hear the motor stall at 25mm/sec. so it`s not reliable enough. And life in the freezer throws up a few issues for my Y axis linear system, so I need to deal with that also.

Trust me my brain is on overload trying to get my project working.
tnx again for all the advice.
Title: Re: Project IceMould. Manipulating M08/M09 command ?
Post by: vmax549 on November 30, 2007, 09:49:10 AM
Will working with the Scode is not any different that working with the Mcode. Mach will still not let you intervene in mid movement.

WHat always worked best was a very fine mist and controlling your paths to get the proper coverage. You also may want to look at a paint spraygun as an applicator. You can control pattern and density by adjusting the head(;-)

(;-) TP