Problems with Z axis calibration ?
Think about this if you have problems with Z-axis calibration.
Some of the problems can be derived from the fact that the Z-axis details have been incorrectly mounted.
The tolerance in the screw holes is quite large and it is easy to mount a detail a little bit.
The example of the picture is the worst possible scenario, but not impossible.
Everything depends on how the detail is placed when the screws are tightened.
The X unit should be used as a template when the top and bottom screws are tightened.
Lower the X unit and tighten the screws to the Z motors. Then raise the device and tighten the top screws. Then the screws should find their correct location.
Other issues may be the Z-screw-cover and the trapezoid nut as described in other forum posts.
Bear MK3 with Bondtech extruder