Home Offset is Applied to Mesh Bed Leveling

[manianac]

After wanting to offset some Slic3r prints, I had left a home offset present with M206. After cleaning my glass and doing a 2x2 mesh level, I found that when starting the process the firmware homes all the axis', then attempts to go to the next position honoring home offset.

In this case it causes the printer to slam into the X endstop, thankfully the belt and motor gave way.

When doing mesh leveling, shouldn't the home offset be ignored?

[thinkyhead]

Yes, or well, sort of. It should add home_offset to the points that it's probing, so they are in the correct relative position. But this also stems from a bug in M206, because when you do this command it should immediately adjust the current_position, but it doesn't. So, you have to do G28 after M206 before the current position will be correctly registered.

So, I will submit a patch for these related issues, and hopefully it will completely take care of the problem.

[thinkyhead]

Thank you for pointing this out @manianac! This is a pretty important issue, even though few people know much about home_offset. I've also been looking at G92 because it seems to me that we should move the software endstops whenever that command is used also. Otherwise after G92 X1000 you can only move… left? … if at all.

[manianac]

Agreed software endstops should be moved with G92 commands, otherwise you're guaranteed to drive right off the edge of your maximum.

I tried #3446 and it fixes G29, thank you!

[thinkyhead]

That's good news @manianac! …

I had to do some additional changes to #3446 to account for home_offset in more places where the mesh bed leveling coordinates are used. It will make a difference in how the Z offset is applied across the mesh, so be sure to give it a try.

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