Mk3s calibration failed after firmware 3.9.3 update  

New Member

Hi guys,

I have mk3s with P.I.N.D.A. 2, everything is working fine untill upgrade firmware to 3.9.3 . I did not change any HW, only firmware.

I tried calibration wizard and when it comes to calibrate first Z point of 4 total, the carriage is misaligned (pinda is not straight over the circle, but more to the left), and there's error on the display:

Calibration failed!

Check the axes and run again.


What did happen? Firmware bug?


Posted : 08/01/2021 9:34 pm
New Member

i had the same thing happen. did you find a fix?

Posted : 10/01/2021 4:49 am
New Member
Posted by: @glenn-3

i had the same thing happen. did you find a fix?

Nope. Waiting for a fix from PrusaLabs. This must be firmware bug, because I did not have changed anything else.


My old fw - worked fine:



New fw  - bug:


Posted : 10/01/2021 2:07 pm
New Member

OMG I've just found it!

At the beginning of the whole calibration process (wizard) the printer head finds most left and most upper point. It searches it using crash detection. But the problem is, that the head is trying to find these points only cca 50mm from it's curent (and not known) position. So in case of the head head is not near these points, it will not find them, store bad points, then go all the way down to the bed, and will not be able to find 1st Z calibration point.

So the solution is:

After the firmware flash, just BEFORE starting the caliration process:

1. Turn off the printer or disconnect from mains 230V.

2. Move the printer head up by rotating both threaded rods so it touches the most upper position, then move cca 10mm down.

3. Move the printer head left manually, so it touches most left position, then move cca 10mm right.


After these 3 steps you can start automatic calibration process (wizard).

Also make sure, that "crash points" are not blocked by any obstacle, ie. cable ties or something else.


|It worked for me and I must say this was finally not a bug caused by newest firware.

This post was modified 2 months ago by R-Man
Posted : 10/01/2021 2:42 pm
Snympi liked

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