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Missing steps
« on: December 15, 2010, 08:10:55 AM »
Hello,

Wonder if there are any tests users have come up with to test for missing steps?
Should the test(s) be performed under a load? or can they be done with no-load?

Trying to narrow down some routing problems.

Octavio

Offline Graham Waterworth

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Re: Missing steps
« Reply #1 on: December 15, 2010, 09:11:51 AM »
Fasten a pointer to the leadscrew and align it with a marker then move the axis and the pointer should be back in line when you go back to the start point.

In most cases its rapid moves that cause the loss of position, try increasing the acceleration time and reducing the velocity a small amount.

Graham
Without engineers the world stops
Re: Missing steps
« Reply #2 on: December 15, 2010, 02:18:34 PM »
Thank you Graham.

Octavio
Re: Missing steps
« Reply #3 on: December 15, 2011, 07:38:09 PM »
Graham, I seem to be having the same problem. I was cutting some slot car track pieces from a 4x8 sheet of MDF and was getting inaccurate spacings between the slots which should be exactly 4" - some were 4" and some were a bit off. Some of the track pieces line up better than others and it is inconsistent where the errors lie.

I have a 5' x 10' R&P table. My velocity is at 400 and my accel is at 12. For the next test I will try 200 vel. and 8 accel. Do you think this will help?

I have a feeling I'm missing steps somewhere. Is that what it sounds like to you?
Thanks,
Jon

Offline Vogavt

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Re: Missing steps
« Reply #4 on: December 20, 2011, 12:31:52 PM »
Fasten a pointer to the leadscrew and align it with a marker then move the axis and the pointer should be back in line when you go back to the start point.

In most cases its rapid moves that cause the loss of position, try increasing the acceleration time and reducing the velocity a small amount.

Graham



Wondered about this one too. I suppose this would be different if you are looking at pulses/linear movement distance vs lost steps.

I would think that once your axes calibration is setup correctly and any backlash has been accounted for you could run a test of several itreations of back and forth motion and see where the pointer lands. I'm not sure that you would/could call that "lost steps" or actually determine whether you do in fact have everything setup correctly.

Could you use a dial test indicator and quantify the amount moved based on the number of pulses sent? Does Mach have a means of showing the count of pulses sent that could be "zeroed" before hand and then make your move and see where you land with the actual DTI reading vs the expected DTI reading?

Sorry offhand I don't remember. Would be a nice feature though.

Vogavt
« Last Edit: December 20, 2011, 12:33:25 PM by Vogavt »

Offline RICH

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Re: Missing steps
« Reply #5 on: December 20, 2011, 06:32:29 PM »