Bed Mesh Leveling Video Guide - using latest Firmware 10x10 grid

[brent113]

Here’s why you can’t use Z fade height:

Effect on printed materials through automatic level adjustment

Great discussion, fun read. The answer is both 1) and 2) are possible, depending on how you have the firmware set. In practice, without doing anything, the answer is 1). If you want 2) you will need to adjust the mesh as the way Snapmaker stores the mesh is incompatible with Marlin’s M420 Z Fade Height. Z fade height gives funny results when the mesh values are very far away from 0. Snapmaker uses the mesh values around 6-7mm because it combines both the bed unlevel characteristics and also …

In short, you (inadvertently, I had to learn this also) instructed the firmware from Z=0 to Z=1mm height to remove 6mm of adjustment, resulting in bizarre behavior.

If you want to apply a compensation to the mesh coordinates and use M206, then Z fade height will work as expected - the fade out value must be greater than the values stored in the mesh, and also must not contain any part of the home offset (like snapmaker does now).