Machsupport Forum
Mach Discussion => FAQs => Topic started by: SimplyDifferent on February 07, 2013, 11:23:26 AM
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I have seen this question asked a couple of times but have not seen an answer posted. My home built CNC Router is not cutting round circles, they are slightly oval. To me, it seems that the X and Y axis are not moving at the same speed or distance of travel per turn, hence an oval as apposed to a circle.
I made a hybrid machine where the X axis is R&P with an A axis slaved to it. The Y and X axis are Acme 5 start precision ground threaded rod. I purchased my NEMA 23 steppers, power supply and breakout board as a kit from CNC Router parts. I also downloaded their 4 axis Mach3 XML configuration files.
This configuraton file seems to assume the Y axis is R&P and I had drastic issues with the this setup. I changed the settings on the Y axis to match the Z axis since it is typically the Amce 5 start rod on most machines. I thought this corrected it as the dished out carvings (from VectorArt 3D) I have tested it on seemed round. However, I did one last night with a cutout and the cutout is slightly oval.
Since the Y axis is 5 start rod and the X axis is R&P, it seems to me the speed/travel settings are not in sync with each other. Do any of you agree, have other suggestions or can tell me how to get the speeds/travel in line with each other? I am utilizing zero back lash nuts and zero backlash couplings so I am confident it is not a backlash issue.
Any thoughts or suggestions will be appreciated.
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These two links should help.
http://www.machsupport.com/forum/index.php/topic,12512.0.html#new
http://www.machsupport.com/forum/index.php/topic,12513.0.html#new
Brett