I found a post here where @dc42 asked if the tool offset was set in the correct direction but it seems nobody responded. So maybe the implementation is incorrect and sets the offset in the wrong direction. This is also consistent with my observations, as when I manually touch the surface with "G30 S-2" at Z-50 and run G1 Z0 the head moves to the upper end stop instead of staying in place as is should. When running G1 Z-100 the head touches the bed again. This implies that the offset is added in the wrong direction.

10,12 would be my choice as hysteresis compensation makes definitly sense for cnc machines having a rather stiff construction

@dc42
I updated to RC4 and everything works as expected now. Also the strange behaviour, when I was setting workpiece coordinates, is gone. I hope that I did not mix different firmware versions of duet web control and reprap when trying to resolve the G30 issue. I can tell it was there from two marks in the milling table

However everything works excellent now. Thank you very much!

Thank you. For now I found a workaround that also allows me to set X0 and Y0 as well when probing for the lower left corner of a milling workpiece.

• Switch to the 1st coordinate system with "G54"
• Move to the workpiece origin
• Run a macro to set the workpiece origin:
  G10 P1 L2 X0 Y0 Z0 ; Reset offsets
  G10 P1 L20 X0 Y0 Z0 ; Set 1st coordinate system origin relative to current position
  G1 X0 Y0 Z0 ; Update display

However this raised another bug. When I work with the workpiece coordinate system, move commands reaching outside the machine coordinate system trigger a unwanted negative Z movement. E.g. G1 X-60 when the machine axes minimum is at X-50, a negative Z movement is performed. I do not really want to start a milling job with this behavior ...

Am I on a completely wrong track here? I want to manually fix the origin of a workpiece and at the same time prevent movements outside the axis limits. It seems strange I am the first having problems with this.

I found a post here where @dc42 asked if the tool offset was set in the correct direction but it seems nobody responded. So maybe the implementation is incorrect and sets the offset in the wrong direction. This is also consistent with my observations, as when I manually touch the surface with "G30 S-2" at Z-50 and run G1 Z0 the head moves to the upper end stop instead of staying in place as is should. When running G1 Z-100 the head touches the bed again. This implies that the offset is added in the wrong direction.

Can somebody confirm that "G30 S-2" for manual Z probing of the tool offset is still working? I am using the latest 1.22 release. The offset seems to be added with the wrong sign and does not produce the same results as:

• Home all
• Drive nozzle down to grab the piece of paper at x=0, y=0.
  [For this example it happened at z=-15.5]
• Send "G10 P0 Z15.5

described here set tool offset to current position