Z lift height when homing

Software / Firmware SKR Boards
1

Just finished my MPCNC build. Squared and produced a, IMO, perfect crown.

Question about Z lift height when homing. When I home X or Y the Z lifts 100mm before moving in either X or Y. How to I change the lift height?

Using a SKR Pro board and CNCjs. Assuming the change has to be made in Marlin but I cannot find the appropriate place to make a change.

Any advice?

Thanks!

2

Don,

Welcome aboard!

That clearance looks a lot high!

I don’t use CNCjs. but in EstlCAM you input the clearance height in the basic settings of the program. I change it when I know I have a situation where there is something on the edge of a cut that I want to make sure the bit can clear.

I’m sure someone who uses that program will jump in here in a moment and explain how to do that in CNCjs.

Mike B.

3

I think this is the setting you are looking for (configuration.h):

//#define Z_HOMING_HEIGHT  4      // (mm) Minimal Z height before homing (G28) for Z clearance above the bed, clamps, ...
                                  // Be sure to have this much clearance over your Z_MAX_POS to prevent grinding.

This value is commented out in the V1 maintained firmware so I’m assuming Marlin is using a default value. You will have to recompile and reflash to use this setting.

If you are really getting 100mm of lift before homing, then there is something else going on here. I get maybe 10mm of lift. Set your display to Marlin mode, and look at the coordinates just before Marlin starts to home. If you see a negative Z value, then that is likely the root of your issue.

4

Thanks Robert!

That was indeed it. I uncommented that line and changed the value to 10. Now lifts lifts Z 10mm before home either X or Y.

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