M1 Coordinate System

[mdtusz]

The coordinate system of the machines is somewhat confusing and could use a bit of a clean-up/consolidation.

Option 1 - "endstop origin":

Set (0,0,0) in machine coordinates to be when the toolhead and bed are against their endstops.

Pros:

• simple

Cons:

• requires machine-specific offsets when positioning the model in a slicer
• possibility for printing off the edge of the bed
• not "expected" behaviour (IMO)

Option 2 - "bed origin":

Set (0,0,0) in machine coordinates to be when the toolhead is at the front left corner of the bed, and just slightly booping the bed. This requires bed leveling to be enabled and used as the Z endstop position will be above the nozzle end.

Pros:

• behaviour is exactly what you (I) would expect. If I move to (0,0,0), I'd expect to go to the origin of my work surface
• setup in slicer means you can position according to your bed - visually, and by measurement

Cons:

• edge cases to consider to avoid crashing nozzle into bed
• not all bed/endstop combinations will have the same dimensions (maybe? I don't actually know)

I prefer 2, but it comes with a few things to consider. Not all machines will have the same measurements for bed dimensions, and offsets from the endstop to the edge of the bed, and probing will be required before being able to go to (0,0,0). These are not insurmountable challenges - we just need to have consensus on which approach to take.