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[Solved] Z-height resetting between prints  

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Alex H
(@amh)
New Member
Z-height resetting between prints

I've had my MK2S for just over a year now and have not had any significant issues. It was a kit build and I updated the firmware (3.2.3) a few days ago, around the time when I started noticing problems.

 

The printer started printing too high, with the extruded plastic not being flattened at all. I tried fiddling with the live-adjust z but, after the value became much larger, I adjusted the PINDA probe height. Following this, I did a full XYZ calibration which went fine and even an extra Z calibration for good measure. I then ran a first layer calibration print (using nGen, 0.20mm with linear advance).

 

After adjusting the z-height to a suitable level (in this case, around -0.500) I then tried to run another print. However, the first layer would not go down properly until I brought it almost twice as low (-0.900 or so). After more PINDA adjustment and further z-calibration, first layer calibration etc. I had the same issue where I would set the live-adjust z value, then have to change it further when starting a new print.

 

I've replicated this a few times, with almost exactly the same results. Any help greatly appreciated.

Posted : 20/07/2019 3:48 pm
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(@)
Illustrious Member
RE: Z-height resetting between prints

If you recently changed firmware, try going back to the prior version you were using.  I've seen something similar in the MK3 latest release, and think they broke something between 3.6 and 3.7 ...

Posted : 20/07/2019 8:39 pm
Frans Krau
(@frans-krau)
Trusted Member
RE: Z-height resetting between prints

I had issue like that. It was solved when I wait with printing until the PINDA is completely cooled down to room temperatuur.

Frans

Frans Krau
Europe, Holland, Apeldoorn...
Posted : 22/07/2019 7:57 am
Alex H
(@amh)
New Member
Topic starter answered:
RE: Z-height resetting between prints

Thanks for the help guys. Downgrading the firmware back to the last version and rerunning some calibrations seems to have worked. I may try swapping between the versions again just to confirm whether or not that was the issue, but, for now, I have a fully functioning printer. Thanks again.

Posted : 25/07/2019 5:54 am
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(@)
Illustrious Member
RE: Z-height resetting between prints
Posted by: FransKrau

I had issue like that. It was solved when I wait with printing until the PINDA is completely cooled down to room temperatuur.

Frans

Yes - that is a work-around for the broken firmware.

Posted : 25/07/2019 9:44 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: Z-height resetting between prints

i have been running 3.7.2 with no problems. you might try doing a factory reset with data clear. good practice is doing a data clear after any firmware change as the data in the eeprom does change between firmware versions

Posted : 25/07/2019 10:30 pm
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(@)
Illustrious Member
RE: Z-height resetting between prints
Posted by: david.a66

i have been running 3.7.2 with no problems. you might try doing a factory reset with data clear. good practice is doing a data clear after any firmware change as the data in the eeprom does change between firmware versions

The issues I've documented occur after a full reset ... and it'd pretty clear it's a coding error based on how it progresses.  The printer simply ignores Z-offset if a mesh level isn't performed. Worse, it seems to remember the last Z-offset used in a prior operation and adds it to itself on subsequent runs.  A power cycle resets the behavior, and the cycle starts over. 

Run 1: Set Z-offset to -.750 

Run 2: Z-offset must be set to -1.500 to achieve same layer 1 as run 1

Run 3: Z-offset must be set to -3.000 achieve same layer 1 as run 1

Power cycle:

Run 4: Z-offset of -3.000 drives nozzle into bed

 

Posted : 26/07/2019 12:38 am
BillC
(@billc)
Reputable Member
RE: Z-height resetting between prints

Why are we talking about MK3/S firmware versions 3.6 and 3.7 in a MK2S forum? The latest firmware for the MK2S is 3.2.3 please be sure to navigate to the MK2/S downloads on Prusa Firmware/Drivers page.

Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor...
Posted : 26/07/2019 1:36 am
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(@)
Illustrious Member
RE: Z-height resetting between prints

The silly forum includes ALL forums in the RECENT category ...  and when Prusa fixes that problem these sorts of cross posts will ebb.

 

Beyond that, there are links between the current MK3 code and the MK2 code, so what affects one can influence the other.

 

This post was modified 2 years ago by --
Posted : 26/07/2019 2:24 am
bobstro
(@bobstro)
Illustrious Member
RE: Z-height resetting between prints
Posted by: Tim

The silly forum includes ALL forums in the RECENT category ...  and when Prusa fixes that problem these sorts of cross posts will ebb.

It would help if the new forum software wouldn't truncate the breadcrumb trail at the top right before the really useful information is displayed.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 26/07/2019 4:12 am
JuanCholo
(@juancholo)
Reputable Member
RE: Z-height resetting between prints

Hi i'm late to the party here however i had the same issue and i had google searched.

maybe this will help another prusa owner in the future.

So there is a nasty bug in the firmware that has been around forever and i had to remind myself of it. because sometimes i forget too going back and forth between different FDM printers.

the MK2S with firmware 3.2.3 will ignore Live-Z information until you run a first layer calibration test with PLA from the calibration menu.

if you do not run the first layer calibration the machine will take Live Z information but treats it wrong and corrupted. so you find yourself setting live z to crazy places like -2.5mm

then when you power cycle it ignores your perfect Z and you once again have to set crazy live z numbers.

and it will ignore it again when you start the next print. going back to a cold pinda does not mater the Live Z is corrupted until a first layer cal is done with PLA. once this is completed the Live Z information is treated correctly from then on.

you must run the first layer calibration through the menu. once you do this the machine will use Live-z setting correctly and allow you to adjust it without it going nuts.

so remember to do the the first layer calibration every time you reset the XYZ calibration then you can run your own live Z calibration from the USB or SD card and have proper live Z usage.

hopefully somebody else googling in the future sees this and it helps. this bug drove and drives people insane and it has been around on the MK2 machine for a long time.

 

“One does not simply use a picture as signature on Prusa forums”...
Posted : 06/09/2020 3:55 am
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