M666 - I can't figure it out

I’m having difficulty understanding the M666 command for adjusting my Z height. When I zero my Z at (0,0) then move to (610,0) and find that my bit is now 1.54mm above the spoilboard, how do I adjust? Also, how many locations can I calibrate and adjust the Z with M666?

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When you home Z up, the firmware touches each motor to the endstop. M666 then moves one motor away from the endstop by that distance.

I always get the positive and negative backwards. So you may have to reverse it.

If you use M666 Z1.54, then one of the motors will back away from the endstop 1.54 more than the first one. -1.54 will switch the offset to the other motor.

It has no effect on the Z at multiple XY positions, that isn’t what this is for. This is for squaring the Z.


Ah…I see. That makes sense. Thanks Jeff!

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