Proposed fix for bug report #27680

[Maker-Paul]

Description

When a Fixed Home Switch/Z stop is used with a proximity probe . The height the level probe triggers above Z0 is incorrectly added on to the mesh probed values. If any offset is used to correct the mesh values the same offset gets applied to the Z0 Home position. Please refer to bug report #27680

Requirements

None.applies to all machines using a fixed Z stop for homing and a Proximity probe for leveling

Benefits

It fixes an incorrect offset being added to level mesh values

Configurations

Modified files.zip

Related Issues

https://github.com//issues/27680

[Maker-Paul]

The Tronxy XY2 pro has a bed level sensor that is subject to environmental instability. Probing the bed within a short space of time is not affected by environmental changes but homing is. This has caused Tronxy owners problems for years with constantly having to reset Z offsets before printing. A fixed Z stop solves the problem of inconsistent homing with minimal cost just by plugging a fixed stop into the unused Z stop socket on the main board. This fix means Marlin works as expected on any machine, not just Tronxy, fitted with both a fixed Z stop and a proximity probe.

[Nuck-TH]

I don't really get why you are trying to get rid of probe Z offset setting. It isn't offset from home position to probe/nozzle, but is distance between probe trigger point and nozzle tip.

[Maker-Paul]

Hi Nuck-TH. The simple answer is I'm not trying to get rid of the probe Z offset.please see bug report #27680 for more info.