X axis randomly moving out of center

[Ndziuban (Nick Dziuban)]

I tried searching my issue but am not exactly sure of the technical terms to look for.

Basically, in random spurts, my shapeoko Pro XXL is attempting to go too far to the right on the X axis. I’ve cut something recently that cut perfect, but the project before it and after it has randomly in the middle of the cut moved itself out of zero on the x axis by about 2 inches. I noticed today when my machine went to the bit setter, that it ran too far to the right and it took a second for the proximity switch to kick on which moved the center over to the left about 2 inches.

I re-initialized and it worked perfectly the next time. When I went to the second part of my cut, it did the bit setter perfectly again but when I came back after the tool path ran it had shifted to the left about 2” again. I’m not sure if my proximity switch is malfunctioning or if something else is happening causing my x axis to become out of center. When I log the machine left to right it runs smooth and stops when it’s supposed to.

[Ed.E (Ed)]

Just a guess; loose set screws on the toothed pulley on the X motor. Check to be sure the set screws are in the correct position in relation to the stepper motor shaft and tight. One set screw tight on the flat spot on the motor shaft, the other tight.

[Zman (MICHAEL ZEMANEK)]

As @Ed.E mentioned, that is probably the issue. After you have confirmed that it is correct, put a witness mark on the pulley.

[Ndziuban (Nick Dziuban)]

I was able to give the set screw a 1/4 turn on the pulley. It still did it again on my second tool path. I think my next steps may be oiling the x axis and replacing the belt.