Setting "Z=0 Datum" - What is it doing?
-
Hi,
Been reading up on mesh bed compensation which I have not used before.
I currently home Z using an optical sensor.
It mentions the need to set a "Z=0 Datum" using a G30 command.
What exactly does this do that homing Z does not do?
Thanks.
-
@fcwilt the mesh needs to know what Z0 is, then points in the mesh can be higher or lower than that
-
@fcwilt said in Setting "Z=0 Datum" - What is it doing?:
What exactly does this do that homing Z does not do?
Homing Z references the bed relative to the axis endstop, probing with G30 references the bed relative to the bed? On a perfect printer they should in theory be the same, so not sure why its an absolute requirement, but clearly probing the bed is going to track any changes due to thermal expansion, wear etc.
-
@bearer said in Setting "Z=0 Datum" - What is it doing?:
Homing Z references the bed relative to the axis endstop, probing with G30 references the bed relative to the bed? On a perfect printer they should in theory be the same, so not sure why its an absolute requirement, but clearly probing the bed is going to track any changes due to thermal expansion, wear etc.
Well that makes sense. Thanks.
Frederick
-
@fcwilt said in Setting "Z=0 Datum" - What is it doing?:
What exactly does this do that homing Z does not do?
If your homeall or homez macro uses G30, then homing will give you the Z=0 Datum.
-
@phaedrux said in Setting "Z=0 Datum" - What is it doing?:
@fcwilt said in Setting "Z=0 Datum" - What is it doing?:
What exactly does this do that homing Z does not do?
If your homeall or homez macro uses G30, then homing will give you the Z=0 Datum.
Thanks. I did read that. I was just wondering about the why since G30 yields the result I expect based on where my current IR sensor homes the bed.
But my tests did not take into account the changes that might occur as the bed/hotend change temperature and that seems to be where using a Z-probe has an advantage.
Thanks again.
Frederick