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Author Topic: Unwanted Step Pulses  (Read 6379 times)

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Re: Unwanted Step Pulses
« Reply #10 on: April 29, 2012, 07:03:28 AM »
What is the resolution of the Z axis ?
A very coarse setting could possibly produce the effect you are seeing due to rounding.
Possible ? ?
Russ
Re: Unwanted Step Pulses
« Reply #11 on: April 29, 2012, 07:05:02 AM »
Assuming also that it's a clean licensed install from Vectric.

Offline RICH

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Re: Unwanted Step Pulses
« Reply #12 on: April 29, 2012, 08:13:36 AM »
Agree Gerry that those lines look a lot deeper than 0.035mm ( 0.0014") and for the deeper cuts you would see it when
the code is simulated.

What microstepping are you using for the Z axis?
If greater than 10 us your wasting your time. Your 276 in oz stepper probably can't hold that positioning. Note that when you microstsep your  torque is is greatly reduced, as much as 50% or greater.  As you make all the numerous small moves you can be loosing or gaining steps / skipping in the Z. May not even hear the skipping and it adds up and may not be repeatable for the same parts of code.

The above shows it's ugly head when doing xyz moves. You could do regular machining  all day and not see the effect.
Changing acceleration, velocity, depth of cut etc doesn't help. That's my experience here if it's motor related. Again very hard to pinpoint since you think it's a mechnical problem.

BUT

Before you focus in on the  above make darn sure there is nothing mechanical that would create what your seeing and definitely make sure it is not the code.

RICH
 


Offline Tweakie.CNC

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Re: Unwanted Step Pulses
« Reply #13 on: April 29, 2012, 08:48:43 AM »
Hi Rich
I have already tried this and am certain that this is not a mechanical issue as the Z axis only moves up never down , only by a small amount but always up , if I watch the DRO for Z then where as it should be cutting at depth of say 5mm then it will alternate from the 5mm that it is supposed to cut to 4.9650 and then back to 5mm , as I say not a great amount , the other thing is that if I remove the stepper motor from the "Z" axis and just hold it in my hand you can see and feel the motor run down to where it would be machining at the required depth and then you can see and feel the motor move a small amount so I am convinced that this is an electrical problem and not mechanical
Thanks
Alan

Hi Alan,

If your Mach3 DRO's are showing the incorrect Z axis movement then the problem is either in you GCode or within Mach3. I trust you are using the fully licensed versions of both Mach3 and Vectric Aspire ??

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

Offline RICH

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Re: Unwanted Step Pulses
« Reply #14 on: April 29, 2012, 08:55:15 AM »
Tweakie,
Not sure what he is seeing in the DRO ...ie; is the line that is running the same as the what the DRO is indicating...
One can single step through the code or simply put a dwell ( G4 ) in the code and compare

RICH

Offline ger21

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Re: Unwanted Step Pulses
« Reply #15 on: April 29, 2012, 09:07:14 AM »
Changing acceleration, velocity, depth of cut etc doesn't help. That's my experience here if it's motor related.

From my experience, if the Z is losing position, then reducing accel will definitely help.

However.

The fact that it appears to lose position, and then get back to position, really points to a mechanical issue to me.
If the Z were to lose steps, it's very unlikely that is will lose in one place, and then regain the exact same amount in another place. Typically, it'll do one of two things. Wither get deeper and deeper. Or slowly lift above the part and stop cutting.

What are the actual accel and velocity settings you're using?
Gerry

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Offline RICH

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Re: Unwanted Step Pulses
« Reply #16 on: April 29, 2012, 10:04:28 AM »
Alan,
Can you post a pic of your Z axis and machine?

Hey Jerry, what you say, and I do agree , that  reducing accel should help.
What I said in reply #12 needs additional or better explaination, but, for now don't want to go there.
Like yourself, desire to eliminate the mechanical and code end of things first.
 
RICH


Offline kcib

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Re: Unwanted Step Pulses
« Reply #17 on: April 29, 2012, 10:44:04 AM »
Hi all
first of all all my software is fully licensed and genuine , secondly I have never said that it was a mechanical issue it is 100% electrical , to start with if it were mechanical you would no be able to remove the "Z" axis stepper motor from machine and not only feel the stepper move a fraction but see it move. As for it being in the Gcode someone else run this program for me using exactly the same steppers and drives fitted to his machine and it ran perfectly so it has to be something related to my machine , would it be anything to do with the PCI parallel port cards I am using ?? I have two in this computer so I might just swap them over to see if it does make any difference. Also the picture I attached in an earlier mail was the wrong one so attached is the correct one both machine one after the other with no changes made to machine etc. the part on the left you can see the lines on the left hand side and the part on the right has the lines on the right as I say no changes were made as soon as one part was finished second one was done.Also Pic of "Z" axis
Thanks
Alan

Offline kcib

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Re: Unwanted Step Pulses
« Reply #18 on: April 29, 2012, 10:53:43 AM »
Need help in loading up the pics to go with my last mail I keep getting this message (Sorry! There is already an attachment with the same filename as the one you tried to upload. Please rename the file and try again.) can anyone help me out ??
Thanks
Alan

Offline kcib

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Re: Unwanted Step Pulses
« Reply #19 on: April 29, 2012, 11:02:47 AM »
Hi all
thanks for all your help but have changed over the two parallel port cards and for some reason all is cured not sure why tat hould be but the most important thing is that the problem has disappeared  ;D
Thanks
Alan