Z Axis calibration failing
My Mk4s suddenly started failing it's Z axis calibration - when I started my most recent print, instead of tapping the build plate, it rammed the nozzle down so hard I thought it might actually bend the plate, and then started grinding the stepper motors in an effort to push it further through. I reran the calibration, including the load cell thinking it might have gotten out of whack. The load cell failed repeatedly until I took the nextruder apart and reassembled it, then it started passing again. But even with the load cell working, the Z axis calibration just rams the nozzle into the print bed and keeps trying to force it through. Do I have a bad load cell? Or is something else going on? The printer has been working fine for about 6 months, in fact it just finished a print which worked perfectly, then this problem.
RE: Z Axis calibration failing
Typo in my initial post - should have said Mk4, not Mk4s, but I can't edit it.
RE: Z Axis calibration failing
I have the same problem as you, after finishing one print with success the z calibration fails ramming the nozzle into the print bed. Testing the load cell it looks like that the sensitivity of the load cell is reduced, I had to tap on the nozzle during the test stronger than I remember during initial tests after assebling the printer some month ago. Could it be that the load cell is aging and looses the sensitivity? If so this is a expensive part to replace (~55.-- €). Bad.
RE: Z Axis calibration failing
I seem to be having the opposite problem. After Mk4 to Mk4S upgrade all calibration tests passed and it printed fine for about a week. Now at the start of a print the Z-Axis stops midway down to the build plate, tries to clean the nozzle in mid air and then complains of a crash detection. I can re-run the calibration routines and everything passes. But, it still repeats this odd behavior. Eventually it will get past this and produce a perfect print.
RE: Z Axis calibration failing
MOAHR - (Mother Of All Hardware Resets)
This solved my problem. Option 2 - Hard Factory Reset.
We had a short power outage several days ago. Maybe that scrambled its brain? All is fine now...