I have had this happen multiple times. Set Z zero and part way thru the cutting, the Z axis will raise about .1". I’ve rerun the program several times and the same thing happens.
I’ve also had a problem while running a pocketing program where a few areas are missed. On a 6 x 9" plaque, there are areas aabout .75 x .75" cut at a different height - usually .8 higher. Problem related to one above?
Gcode generated by Aspire and using UGS new platform to send. Have upgraded to GRBL 1.x. Have reprogrammed the 3D file to attempt to eliminate this by using smaller and larger tools (started with a .25" endmill). Have changed feed up and down. No Change. Any thoughts?