Negative coating thickness bug

If the nozzle is a little too high at z=0, I would use "Coating Thickness" EEPROM setting to a negative number.  At first it worked as expected, the nozzle would start a little bit lower.  However, after a Z-hop, the z height would lose the offset and would be printing slightly higher as though the offset didn't exist.

For example, Z=0, Coating thickness = -2mm.  The print's perimeter would be flat.  Z-hop occurs.  Infill of the print is being dropped from 2mm in the air.

Perhaps Coating Thickness should be allowed to be set to 0 or higher, not lower than 0.


  • Do you have ALWAYS_CHECK_ENDSTOPS enabled? To me it sounds like on first move with homing it is ignored when applying offset but on hop it is enabled when going down and z move stops as soon as z endstop is triggered.

    In this combination endstop check should be disabled or you move endstop down so it gets triggered at real z=0 with coating thickness 0 or positive. In both cases it would then have no issues with z-hop, but you might press bed down so it must be spring loaded so this does not damage bed and not move xy when it does.
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