My circles are lemons (machine problem) SO3

[spasmfingers (Nick)]

My machine cuts circles as lemons; I can’t figure out how to fix this problem.

Lemons consistently point in one direction or the other depending on cut type. (inside/outside cuts)

Pictures:
https://imgur.com/4i6LYia

of cc
https://imgur.com/bmfYwHJ

[Album] Imgur

I have tried:
-Adjusting belts
-tightening and adjusting several parts of the machine
-calibrating x and y
-changing materials, changing feeds and speeds
-different work holding methods
-a variety of end mill sizes, flutes, brands
-running old files that didn’t have this issue (they do now)

[spasmfingers (Nick)]

I’ve gotten it to the point where I can cut perfect squares, but my circles still come out as ovals/lemons, and my curves distorted. The squares really do come out with the side being the same length. The only thing I can think to blame at this point is the z axis plate which seems to be pushed back and forth (y axis)

If anyone has an idea how I can strengthen my axis (without getting a whole new system) or any other fix to this issue, please help.

[mikep]

That’s backlash. You have a pulley on X or Y that is loose - the axle is turning a little (about the distance of the flat on the axle) before the pulley starts turning. If everything was oblong in the same direction (no points) that would be x/y belt calibration or machine squaring.

[WillAdams (William Adams (Carbide 3D))]

Please check the pulley set screws: http://docs.carbide3d.com/shapeoko-faq/shapeoko-3-how-to-check-the-pulley-set-screws/

and make sure the belt tension is appropriate: http://docs.carbide3d.com/assembly/shapeoko/xxl/step-5-belting/

[spasmfingers (Nick)]

UPDATE: One of my motors is not working.

When I turn the machine on and let it sit for a while, I can feel the other three motors are warm, one of them is not however. I opened up the back panel and everything seems to be connected just fine. I think my motor is dead.

[WillAdams (William Adams (Carbide 3D))]

Usually it’s a blown stepper driver — we have instructions for testing the components at: https://www.shapeoko.com/wiki/index.php/SO3_Function_Test#Y-axis_not_working_properly

Please test the various components and let us know at support@carbide3d.com and we’ll do our best to help you sort this out.

[mikep]

Also check the cables and extensions, some people have had problems with the cables themselves pulling apart.