I have a commercial 2'x4' cnc with rack and pinion drive on X & Y. The machine cuts about 20 mil over size on the far side of the x axis whether its a 3" rectangle or 6" circle. Its close to spot on near x0. The pinion doesn't show wear and is tight against the rack. I've made sure the rack is straight with a straight edge. Checking the x axis resolution shows that it is spot on. Y axis doesn't appear to have this issue. Belt is tight.


I've been cutting mdf for testing this with 1/4" bit, 1/8" DOC, just 50ipm feed at 12k rpm.

What is possibly the issue? Some weird electronics problem?