I have a sphinx 1050. The z axis skips or jumps and will knock the cut off of where it was set to. I’ll start making .2mm cuts and end up with a 3-7mm cutting depth. The belt is tight. The pullys are tight. I’m not sure why it’s doing this.
Current adjustment on that axis's driver? But just a heads up on something similar that once ruined a couple jobs for me. Took me several days to figure out... The DWP611 has 1/4inch collet. Somehow I got some 6mm endmills off ebay (ordered 1/4 you know how that goes) and i didnt notice. The 6mm tightens, but with 0.35mm less (1/4in = 6.35mm) the shank is just a little looser even when fully tightened (nut bottoms out) that you don't immediately notice the bit is loose in the collet. Then while cutting, the downward flutes "pull" the bit out the collet - ie deeper into the material, the longer you cut. Those endmills worked great though, so instead of tossing them out, I just added some 0.12mm shim stock wrapped once around the shank. For a while... And then eventually got a 6mm collet from Elaire. Moral of the story: It might not be what you think it is (;
it probabyl has a sticky spot. make sure all the wheels etc are clean. then, in your controller, halve the max speed and acceleration settings for the Z axis. if this fixes it, then it was just trying to go too fast for the motor to overcome the weight or the sticky spot or dirt etc. this is because the faster stepper motors turn the less power they have.