@schild0r, on Duet 3 MB6HC the un-calibrated errors can be quite large. Typically, TEMP0, TEMP1 and TEMP2 have significant error at low temperatures only, and different TEMP3 has significant error at high temperatures only.
@dc42: Does it sound like a bug for the probe offset to be applied over and over on repeated G30 P3 X0 Y180 Z-99999 F2000 calls?
That doesn't sound right. Please post the complete macro file you are running, and your config.g file, and tell us which firmware version you are running.
I was originally on 3.0, and now on 3.01-RC4
Unfortunately, I did not save the macro before modifying it. That is my fault.
I did find one error in my code, in asking it to probe at X0, when my probe has a +12mm offset. I feel like the firmware should catch this more gracefully though. It appears that it ignores the endstop switch and the X0 minimum designation, and tries to aggressively get the probe to X0 anyway, which hard crashes into the machine limit and jumps the belts.
Also, it appears that I can't probe more than 32 points before I am "out of range"
I'll leave that one to David, but I would advise to consider a more accurate probe, or just use the manual calibration for now. If you want any info on one particular probing system that might help see my signature.