z axis error

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04 Jun 2010 18:24 - 04 Jun 2010 18:25 #3067 by david_r
z axis error was created by david_r
Hi,

I'm new on the forum, but I use emc2 for a few years.

I've encountered a strange problem when machining something that has a lot of tiny Z axis moves - like lithopanes or fine 3d engravings.

I've made a few tests and here are the results:

When running this code:
#1000=100 ( loop 100 times )
( the next loop has no delays after moves )
( tests direction hold times on driver config and also max accel setting )
o101 while [#1000]
G0 Z0.009
G0 Z-0.009
#1000 = [#1000 - 1]
o101 endwhile
G0 Z0
( msg, Done...Z should be exactly 0.000mm above table )
M2

Result is OK, my dial indicator shows 0.000mm

But when running this code:
#1000=100 ( loop 100 times )
( the next loop has no delays after moves )
( tests direction hold times on driver config and also max accel setting )
o101 while [#1000]
G0 Z0.001
G0 Z-0.009
#1000 = [#1000 - 1]
o101 endwhile
G0 Z0
( msg, Done...Z should be exactly 0.000mm above table )
M2

Result is not OK, my dial indicator shows -0.620mm
Lowering Max Velocity and Max Acceleration does not help.

What is the cause of this problem and how to fix it?

Machine setup: EMC 2.3.5, stepper motors, gecko G212, HIWIN ballscrews, HIWIN linear rails,...
Attached picture shows errors on the right side, where is a lot of tiny Z axis moves, and perfectly flat plane on the left side.

Thanks,
David

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Last edit: 04 Jun 2010 18:25 by david_r.

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05 Jun 2010 10:14 - 05 Jun 2010 10:16 #3070 by david_r
Replied by david_r on topic Re:z axis error
Hi,

I believe the problem is solved - thanks KimK.

After changing gecko from half step to 10 micro-stepping, here are the results.



I must make something bigger to be sure, but I believe that micro-stepping solved the problem.

David
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Last edit: 05 Jun 2010 10:16 by david_r. Reason: file too big

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05 Jun 2010 10:18 #3071 by david_r
Replied by david_r on topic Re:z axis error
Different angle:

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05 Jun 2010 17:23 #3074 by david_r
Replied by david_r on topic Re:z axis error (solved)
Problem solved.

Changing stepper controller from half step to 10 micro stepping did the trick.
I've machined the same lithopane again and now it came out OK.

But I'm still wandering if there is a software solution??

David

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