Hello, I've been having an issue with my converted cnc milling machine that seems to be progressively getting worse. It seems to be losing steps of sorts on the X axis only.

The machine uses Pacific Scientific Stepper Drivers and Powermax II stepper motors (P22NRFB-LNN-NS-00).

I've narrowed it down to being a motor issue. I've picked up 0,0,0 and ran a program without cutting any metal and the error on the x was approximately 0.9mm.

The second time I repeated the same process and had 0.5mm of error on the x axis.

I believe that this isn't a controller offset issue as I ran the identical program both times from the same position. The x axis everything is moving freely, I just disassembled it to verify and everything is nice and smooth.

Sitting idle (no motion commanded, machine on to pump way lube only), the stepper motor for the X axis is much warmer (about 85 degrees F vs the Y axis at 75 degrees)

I'm looking for opinions, could my issue be the motor? Could it be the driver?

Thanks
Jeremy