My circles are lemons (machine problem) SO3

(Nick) #1

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)


of cc

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)

(Nick) #2

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) #3

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.

(William Adams) #4

Please check the pulley set screws:

and make sure the belt tension is appropriate:

(Nick) #5

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.

(William Adams) #6

Usually it’s a blown stepper driver — we have instructions for testing the components at:

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

(mikep) #7

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