Z calibration failure  

RE: Z calibration failure

Did you do a full reset with data clear? EEPROM constants are often not cleared when flashing new firmware and they cause issues.

btw, it's normal for a home to miss the dot until after the XYZ cal is done. 

I've read it sometimes helps to manually force the extruder far left stop; and that doing a manual force Z to the top to level - move the axis up until it hammers on both stops - is somehow helpful for getting past Z-cal.  Seems like black magic to me, but there's been enough reports it works.  

The Z-level error often comes from a PINDA that is too high ... or an unstable print stand (new issues in how 3.8 does mesh leveling). 

No definite "do this to fix it", but a couple things to try.

RE: Z calibration failure

I'm in the same boat.

My 2.5s has been printing awesome all year. I have not upgraded FW in quite awhile.

Saw nag screen to I  upgraded FW to 3.8.1-2869.   Getting same problem as William-S13

I did a factory reset.. same issue

Anyone ?

RE: Z calibration failure

Actually just fixed my issue.

I have a MK2.5  and installed the FW for MK2.5S

Reverted to the MK2.5 FW and all is good

RE: Z calibration failure

@david-c51

Well, I had better try his as well.

After discussion with Michael and Jakob I ordered a new PINDA and that made no difference.

One thing I noticed was that if I do 'autohome' it moves to the correct position, with the pinda right over the first magnet target. If I 'show end stops' I get z,x,z=0.

At this point I can run bed leveling (3x3) and it works.

However if I run 'calibrate xyz' or the wizard it fails with the PINDA about 5cm to the left of were it should be ( so not overlapping the circle at all) as before. If I now run 'show end stops' i get x,y,z, = 0 again, when I can see x is about -5cm from were it should be.

Not sure if this will give any clues......

RE: Z calibration failure

Well, 3.7.2_2363 for 2.5 works fine, calibrates perfectly. I will work forward tomorrow through the later versions and see if they all work OK. This is a 2.5S i'm using; I wonder what the difference is?

RE: Z calibration failure

I'll retract part of my last post...  I'm 99% sure I have a 2.5S  ( how can i tell for sure?)  feel stupid as I've been away from printing with the for a couple months.

.. It won't calibrate on the 2.5S firmware but will on 2.5 FW

Can anyone tell me how to verify 100% if I have 2.5 or 2.5s

RE: Z calibration failure

I replaced the PINDA this afternoon on my 2.5S, not a quick job.

After this I loaded back up 2.7.2 for 2.5 (not S) and that worked fine. Calibrated and everything.

Loaded up 3.8.1.-rc1 for 2.5S and it fails on calibration on first magnet position. Tried it several times, fails same place every time, no retrys.

Loaded up 3.8.1-rc1 for 2.5 (Not S) and works perfectly.

Any clues anyone? I can do a video if that would help.

RE: Z calibration failure

Good Lord.. does anyone even read this forum.. Dead dead

RE: Z calibration failure

Posted by: @david-c51

Good Lord.. does anyone even read this forum.. Dead dead

You might do well to just contact support. A PM to @joantabb might be worth a shot as she's got a stable of Prusas of various vintage.

RE: Z calibration failure

@bobstro

I know.. Just it seems there are more users than just me having this issue. Thought it might spur some more feedback here.

I'll hit up Joan

RE: Z calibration failure

Having the EXACT same issue!  I cannot find any solution to this ridiculous issue that is clearly caused by the firmware upgrade!

My Mk2.5S has been working fine, but today I decided to finally upgrade the firmware to 3.8.1 (I think I had 3.6 before)
So now all the sudden I get a calibration error when performing the Z calibration test. "Check the axis and run test again".
I didn't change a single thing other than the firmware!

It doesn't even make it to the first calibration point before getting the error. After starting the XYZ calibration you have to turn the knob to raise the Z axis all the way to the top, once you accomplish this you click know to confirm. Then it says to make sure nozzle is clean, when you confirm that it is it then starts lowering Z and says "Measuring reference height of calibration point 1 of 9" When it gets back to the bottom it immediately gives a "Calibration failed" error "Check the axes and run again"
Tried going down to firmware 3.7 and then 3.6 and I still have the same issue.

Why are there 2 different locations for Auto Home? When I go to Calibration and select Auto home is goes to point 1 and gets fairly close to the circle and the red light on the Pinda turns off, but when I go to XYZ Calibration it goes to a very different Auto Home location and the Pinda light remains on.

I have also performed a factory reset, and several XYZ calibration resets.
Reset PINDA height and it's right on the money at 1mm.

RE: Z calibration failure

@randy-h

Sounds the same as mine. I needed to get some things printed, so I'm using 3.8.1 for 2.5 (not s) and that works fine.

RE: Z calibration failure

Posted by: @william-s13

@randy-h

Sounds the same as mine. I needed to get some things printed, so I'm using 3.8.1 for 2.5 (not s) and that works fine.

I just tried the 3.8.1 for the MK2.5 (NON S) and the printer actually made it past the point where it has been failing everytime, however it crash into the bed on the 4th (out of 9) point.  Not sure why it would do that, if it was fine for the first 3 points.   It crashed pretty hard too, not just a light touch.
So anyway this definitely confirms that there is an issue with the firmware which is what I have been saying all along!

RE: Z calibration failure

Figured out the whole problem after several hours of chatting with Prusa support!

Ok, so here's the deal... Prusa decided it would be a great idea to confuse the $%*! out of everyone by the way they name the upgrades!
I originally bought an MK2S then I later decided to upgrade to the MK2.5, well thinking that I already had the MK2S and updating to the 2.5 it would make it an MK2.5S  Right?  WRONG!!!  It would still be an MK2.5!
There is an MK2.5S that came out 03/2019 which uses a completely different extruder body thus causing the whole Z calibration failure! (The MK2.5 uses an R5 body and my original 2.5 upgrade had an R3 extruder body)
What kind of moron would use the same name for someting completely different!?

Here is the link to the upgrade kit for the MK2.5 to the MK2.5S where you can read about the differences between the 2 very different models:
https://shop.prusa3d.com/en/upgrades/899-original-prusa-i3-mk25-to-mk25s-upgrade-kit.html

I hope that my 2 days of frustration and wasted time with support chat will help save you guys from dealing with this BS in the future!

SO MAKE SURE YOU DOWNLOAD THE RIGHT FIRMWARE FROM NOW ON!

RE: Z calibration failure

As an FYI, the PINDA location over the spot is not going to be valid until AFTER the XYZ cal has completed.  If you are seeing the PINDA over the spot when you run HOME, then the printer is using old cal constants.  

RE: Z calibration failure

Posted by: @tim-m30

As an FYI, the PINDA location over the spot is not going to be valid until AFTER the XYZ cal has completed.  If you are seeing the PINDA over the spot when you run HOME, then the printer is using old cal constants.  

 

Not true, but it doesnt matter now, the problem has been resolved.

RE: Z calibration failure

Posted by: @randy-h

Posted by: @tim-m30

As an FYI, the PINDA location over the spot is not going to be valid until AFTER the XYZ cal has completed.  If you are seeing the PINDA over the spot when you run HOME, then the printer is using old cal constants.  

 

Not true, but it doesnt matter now, the problem has been resolved.

When the printer is built, or after a factory reset with data clear, there are no XYZ calibrations.  When it homes, it simply bangs against the end stops and moves away a predetermined spacing and calls that home.   

After successful XYZ calibration, the printer stores the now known offsets that allow the printer to position over the first calibration point. 

Subsequent XYZ cals may use this stored data, or not, depending on firmware and cal constant state; and an auto-home from the menu will generally use the cal constants and position over the dot as expected. 

In any case, this is why an autohome appears to work normally and homes over the cal point while an XYZ cal does not.

RE: Z calibration failure

Hi @randy-h and others. My problem is similar but different (I think!) it's not resolved but I'm almost certain it's a firmware issue now. I just need to figure out which one is the right one.

I upgraded hardware from a 2s to a 2.5S through:

• UPG-MK2-MK2.5S-BLK-PEI
  • Original Prusa i3 MK2/S to MK2.5S upgrade kit - Spring steel sheet : Spring steel sheet with smooth double-sided PEI sheet
    and
• MMU2S-MK3S-ORG
  • Original Prusa i3 MK2.5S/MK3S Multi Material 2S upgrade kit (MMU2S) - color : Orange printed parts

By your logic I believe that should make my printer a 2.5S (it clearly says 2.5S upgrade). Despite a glitch on the Bondtech component delivery (which got sorted very quickly) its been working now for months.

• I did one firmware upgrade to:
  • "prusa3d_fw_MK25S_3_7_2_2363_RAMBo13a_en-cz.hex"
  • and it was still going well
• Firmware update today:
  • "prusa3d_fw_MK25S_3_8_1_2869_RAMBo13a_en-cz.hex"
  • and it now fails XYZ calibration

There are 3 phases of calibration on 4 points (notation: Front, Rear, Right Left) in the sequence FL, FR, RR, RL

1. course-circular
2. scanning-fine
3. diagonal-fine

Fl and FR goes OK and centres reasonably over the dotted circles. Then the grief starts:

RR:

• Does 1 OK
• When it does 2 it seems to pick up a position too far back (it "squeeks" when it's over the dotted circle but then squeeks a lot as it pulls back past the bed extents.
• It does 3 over the entirely wrong spot (too far back)

RL

Does 1 and 2 and 3 (seemingly in the correct position)

The printer then says " XYZ Calibration Failed. Please consult the manual."

No surprise really when you consider how far back the RR calibration was (about 10mm out).

Of course this *could* be related to a PINDA height issue. The "LCD Menu -> Calibration -> Show end stops" shows the pinda probe working fine.

RE: Z calibration failure

@greg-s23

You should be using if I understand you correctly... You have an MK2.5S with MM 2S correct?

FIRMWARE 3.8.1 (1.0.6)
https://cdn.prusa3d.com/downloads/firmware/prusa3d_fw_3_8_1_MK3S_1_0_6_MMU2S.zip#_ga=2.79604114.704253409.1575769136-1891738591.1575333182