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Z Calibration Issues  

New Member
Z Calibration Issues

I'm trying to work through some bed-leveling issues but every time I touch something, things get worse.

Currently, I'm trying to just run the Z-Calibration and it consistently fails every time on the fourth calibration point.  The nozzle's pretty clean, but every time it comes down it tries to push 2mm too far into the heatbed.

Z Calibration Issue

(snipped the video down to just the calibration points)

This isn't a new printer, and it's been working fine for years now until I 1) updated the firmware and 2) tried to figure out what's behind some consistently poor adhesion in a single spot.  To that end I've unmounted the heatbed, tightened the U-bolts (I'd noticed some significant wiggle) and remounted the heatbed.  I can't see why that would be responsible for this.  I've recalibrated the PINDA a couple of times (at ~1mm higher than the nozzle and at .05mm than the nozzle), with the same behavior.  The magnets on the heatbed appear to still be magnetic.

I'm at a loss as to what to try next. 

Any guidance?  Thanks in advance!

Posted : 19/03/2023 11:08 pm
RE: Z Calibration Issues

this sort of problem can be caused by the X Axis assembly not being parallel to the bed surface

so Turn the printer on, 

The printer doesn't currently know where the extruder is...  no problem... 

once the LCD Display settles to the normal 'At Rest' screen, 
Press and hold the LCD Control knob for a couple of seconds, and you should have the option to raise or lower the Z height... 
At this stage the printer will assume that it is already as low as it can go (Safety feature) 
Wind the knob to get the extruder as high as possible. the aim, is to get BOTH SIDES of the X axis assembly to rattle against the Z axis top brackets. 

You may well fail on the first attempt. 

Turn the printer odd, wait a couple of seconds, 
Turn the printer back on. 
the printer still doesn't know where the extruder is, so once again, press and hold the LCD Knob. wind the knob until the X Axis rattles against the Z axis top brackets ( you should be successful, this time... )
When you have topped out the X axis (MaXimum Z height) select autohome, from the LCD Menu. and the printer should lower the extruder to the home position. 
NOW the printer knows where the print head is....  🙂

now try running z calibration again. and hopefully you will have more success
regards Joan


I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 20/03/2023 12:15 am
New Member
Topic starter answered:
RE: Z Calibration Issues

It's been pointed out that I need the sheet on the bed to do this.  D'oh!  Giving that a shot in the morning.

Posted : 20/03/2023 12:43 am
New Member
RE: Z Calibration Issues

I have an issue with Z axes calibration error. i have a bitotech extruder on the Mk3s printer. I will print but i can not do a Z axes calibration. I get " Z axes"

Firmware Prusa 3d Mk3s 381 2869 If i skip this calibration the printer does print okay but am concerned that it does no calibrate properly.

Posted : 23/03/2023 8:14 pm