You’re not missing something obvious here, but there is a way to do this. Several ways in fact. I think you’re after item 1, but here’s everything I know just in case.
- Touchscreen Z offset
- M421 Q command
- M206
- G1029 D which is a secret undocumented gcode Snapmaker added.
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Use the Z offset function in the touchscreen. I believe it’s saved between power cycles, and is great for quickly adjusting a z offset.
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It’s not as straightforward as you probably hope, but the machine stores the Z offset embedded in the mesh, which can be viewed with M420 V. So the most correct way of adjusting the Z offset is to add or subtract a constant from each mesh point. This can be done with M421 Q I0 J0, etc, for each point.
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Another way is to ignore that and just set a home offset with M206, but that will not be reset next time you calibrate and can cause an issue if you forget to reset it to 0.
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The G1029 D command does all of the work of M421 Q for you, but I haven’t personally run it, just seen it in the source code.
- You’ll need to know the delta you want to change it by. If you have to measure it G42 to the middle mesh coordinate (if you are using 3x3 the middle is I1 G1, if 5x5 it’s I2 J2). If at Z=0 you measure a gap of 0.1mm, your delta is 0.1.
- Then set the Z, then issue this terminal command
G1029 D0, but where the 0 is replaced with the delta you want to offset the matrix by. For the above example,G1029 D0.1
- This last way is what reading the source code indicates it should be, however, again, I haven’t personally run this. It’s safe to run in the sense you can always recalibrate, but don’t just issue that command and then zip down to Z=0 or you might crash something. Also, whenever you change the offset I believe it’s safest to G28 home before doing another move. It’s not strictly required, but there’s weird behavior sometimes when you’re close to the bed and the mesh is changing, better safe than accidentally crashing.