Quote Originally Posted by CalifDan View Post
but the .1 shift on the y axis I do not understand.
As others have pointed out, this is difficult to diagnose. It's possible that it's s software problem, but that's not where I would start. It's usually skipped steps on the motor or a skipping belt.

If you can precisely measure the amount of the shift with calipers, see if it's a multiple of *exactly* 2mm. If so, it may be a belt skip. If it's not exactly a multiple of 2mm, it's not the belt. Friction or inertia (or an outside force) probably overcame the motor's holding torque and it skipped some steps. By "outside force" I mean things like bumping the printer or getting your finger caught between the bed and the Y idler while trying to feel the belt tension. Not that I would know anything about that.

If it only happened once, ignore it. If it keeps happening, you can try making sure your mechanics are moving freely and try slowing down.