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dispensing liquid with Mach 3
« on: March 25, 2010, 11:07:18 PM »
Hello,

I want to dispense liquid with Mach 3 . I have a peristaltic pump that is driven by a stepper motor (X ul per step) so the hardware does not look like a problem.  Is there a way to use the spindle controls to run the pump? or could I use the A axis?  The G code should be relatively simple. I need to be able to select the wells to add the liquid to and how deep the wells are.  The wells will all be the same size and evenly spaced in a 10 by 12 format. Any ideas.

Thanks,
Todd

Offline Tweakie.CNC

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Re: dispensing liquid with Mach 3
« Reply #1 on: March 26, 2010, 04:58:07 AM »
Hi Todd,

I think that using the A Axis to drive the pump would be the best solution - that way you have complete control over the volume dispensed and you could also include a small reverse direction to the A Axis after dispensing to prevent unwanted drips at the nozzle when moving to the next X-Y position.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline RICH

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Re: dispensing liquid with Mach 3
« Reply #2 on: March 26, 2010, 09:16:58 AM »
Todd,
Using the A axis as an indexer such that a part of a degree per revolution is equal to so manny uL would be the way to go. Of course you will need to calibrate the pump. Don't know how acccurately the volume needs  to be or amount of hold up you will require so the "system" can be more involved than just a pump. I would not recommend reversing the pump as that will affect the dispensing accuracy. If accuracy comes into play then a syringe pump may be more appropriate. I assume you will be doing just just single dispensing and not multiple which surely is more complex becuase of split flow. Additionaly you would probably need a second operating pump (not stand by) but  operating / swing pump. Additional non automated control can be added but is rather fluid dependant.
The basic code would be rather simple with just an x & y direction and then a cycle of the z and a rotation, but depending on the complexity of the
process additional coding and monitoring of the dispensing  will be required. Timing shoild be reviewed to see if the system provides required output of production.
Just some thoughts on it all, FWIW
RICH
Re: dispensing liquid with Mach 3
« Reply #3 on: July 15, 2015, 01:31:24 PM »
Hello,

my name is Juergen an i have constructed a mechanical cnc-Dispensing machine for epoxy.
I use a stepper motor as a spindle and I controll it with  M3 and M4 in combination with a dwell time G4 Pxx.
I am not really happy about this solution. I would like to stop the spindle with M5 before the endpoint.
The problem now is, that the machine stopps on realizing M5 for al little time and drops out glue on this position.
Is there any better solution für realising the dispensing function? I want to dispens closed writings or signs, not just some points of glue on defined positions.
I hope anybody has some ideas oder experiences, it would be great :D
Thanks,
Juergen

Offline Tweakie.CNC

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Re: dispensing liquid with Mach 3
« Reply #4 on: July 15, 2015, 04:32:17 PM »
Hi Juergen,

My thoughts would be (as I have already mentioned in an earlier post)  to define the A axis as linear,  move it the required amount to dispense the liquid (glue) then reverse its direction for a few steps to prevent the drips when the X and Y axis move the head to the next location. This can, in my opinion, be easily controlled from a macro function.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: dispensing liquid with Mach 3
« Reply #5 on: July 16, 2015, 12:01:33 AM »
Hi Tweaky,
thanks for your answer.
My problem is, that the a-axis can not be just put on or off.
If i write for example a line with the g-code:
G1 X100 Y0 A90
...the line will be finished and the next line has to get another value for A.
That is really difficult to program. A longer line to extrude has to get another A-value for the same mass of glue.
G1 X200 Yo A180
In my opinion, the way with the a-axis only works with glueing some points on defined positions?
Is this right?

Juergen




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Re: dispensing liquid with Mach 3
« Reply #6 on: July 16, 2015, 02:17:51 AM »
Hi Juergen,

Obviously it all needs tailoring to your specific application but why not have the actual dispensing carried out as an 'Incremental' move returning to 'Absolute' after the event.

G1 X100 Y0
G91 A90
G90


Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: dispensing liquid with Mach 3
« Reply #7 on: July 16, 2015, 04:52:52 AM »
Hi,

the lines are finished step by step.
In the case, you have written, the machine goes to X100 Y0 and starts by arriviing at this point the extruder.
I want to start the extruder while going to X100 Yo.
Is there a mistake in my brain?
Is it generally possible to say mach3 not to stop on M5?

Juergen

Offline BR549

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Re: dispensing liquid with Mach 3
« Reply #8 on: July 16, 2015, 09:51:42 PM »
I would try setting up the dispensor as a step direction spindle running the stepper to drive the pump.

The S word would control the volume per inch of travel

G1 x10 Y0 M3 s100
y10
x0
y0 M5

the stepper motor is very precise as to start/stop  .

You also HAVE precise process control by being able to vary both the Feedarte (FRO) and dispencing volume (SSO) on the fly.

Just a thought, (;-) TP
« Last Edit: July 16, 2015, 09:56:13 PM by BR549 »

Offline RICH

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Re: dispensing liquid with Mach 3
« Reply #9 on: July 16, 2015, 11:16:30 PM »
Terry gave a good example of the syringe pump use.

You may want look at how they are modeling using an Ardurando ? and gcode since that is more like an extruder in functionality
and let me say that it quite impressive, but unfortunately I don't know much of the details.
If my friend can melt polymer line / control it, and lay it down quite accurately I would guess that high vicousity material can be done in a similar fashion.

Just a thought,

RICH