Mesh Bed Leveling error after Z axis moved above a certain height
If for any reason the Z-Axis is moved above 150 or so next time Mesh Bed Leveling runs when it samples third spot it says An error has occurred Calibrating Z. If I try to reset or click menu button it starts Calibration procedure. During Z Calibration when it gets about 7mm from the top the Right side stepper stops and the Left side goes to the top and then returns home. If I try to print the same thing happens again. I can use a level and manually adjust the it and it will print fine, until the Z-Axis gets too high then same thing. It is not a random event.
Should have mentioned I am using MK3S with Firmware version 3.8.1
The issue is that the printer does not "remember" the zero position for the Z-axis after power-off. As a matter of fact, for none of the axes. So, each time the printer is powered on, it will consider the zero position wherever the Z-axis is. The position will be corrected once it starts to print and does the mesh bed leveling, but you need to be careful to avoid moving the Z-axis too high.
I've had the exact same problem. After powering on the printer and assuming that the printer knows where to stop, I wanted to raise the Z-axis completely to clean the nozzle. Big mistake. The X-axis carriage hit the top mounts and the calibration was gone.
Trying to calibrate the printer afterwards failed. I've tried a factory reset. No luck.
In the end I logged a case with Prusa Support and they have asked me to roll back the firmware to 3.8.0 ( https://www.prusa3d.com/drivers/firmware-changelog/#mk3s).
To roll back the firmware, simply follow the same process as for the upgrade, but choose the 3.8.0 image.
After flashing the 3.8.0 calibration succeeded and I was good to go.
The firmware Always considers the extruder to be at Z=0 when switches on, because it has no way fo knowing where it is, however if you execute an auto home from the LCD Menu the printer will use the Pinda to find the buildplate. and reset Home to the correct position.
I really appreciate your replies, the problem is not homing or powering the printer on. The problem presents itself when the Z-axis goes higher than 60 to 70% of maximum height It doesn't matter if I have just powered on or printing all day. The next time it runs Mesh Bed Leveling (regardless where it starts from, last position or if auto homed, wherever). When printer samples the third spot I get the error. i don' remember exactly what it says but basically:
An Error Has Occurred (on next line) Calibrating Z
If I click the select button or Reset Button it performs Z Calibration, however, instead of both sides going all the way to the top the Left side goes all the way, but the right side stops 6 or 7 mm before the top. Then returns home If I try to run Mesh Bed Leveling or start a print the exact same sequence of events. If I take a level and place it on the X-axes rod I can raise/lower the sides until it is level. It will run perfectly well, it can be powered off and next time powered on it runs just fine. Until the next time Z gets too high!
I guess I could try rolling back the firmware and then reinstalling 3.8.1. I really don't want to I've been using it since October.
Thank You Again!!