RE: Z and Y axis calibration problem
Unfortunately, it does not in my case. Even after moving manually all the way up, the z axis will still only lower to around 30% and not to 0%.
RE: Z and Y axis calibration problem
For me, the self-test passes successfully and I was even able to print the test prusa key chain without any issues. However the problem starts when I select "Calibrate Z axis" where the Z axis goes down to 30% and then stops while the printer tells me that it's height is 0mm from the print sheet.
What seems to fix this is to run the XYZ axis test again but I have no idea why the Z axis calibration messes up so badly.
RE: Z and Y axis calibration problem
Wow, I am also having this mysterious failure to calibrate z axis error. I upgrade to 3.9 and I can get every test to pass except the z axis. It errors saying check the loadcell, but that always passes its test just fine and prusa cs even sent me a replacement loadcell/hearsink but it has made no difference. I have spent probably close to 20 hours troubleshooting this with cs and still no solution. Printer is useless until I can get a solution that actually works.
RE: Z and Y axis calibration problem
This is exactly what happens with my MK3.9, only that re-running the test does not fix a thing.
I have a feeling that the z-axis calibration moves down for x seconds, stops, and tries to find the zero positoin from there - which does not happen, if it's still 7cm up in the air. Maybe the z-axis speed is different for different MK3 versions from which the conversion kit construction started, so that x seconds for all MK3.9s won't work?
...However the problem starts when I select "Calibrate Z axis" where the Z axis goes down to 30% and then stops while the printer tells me that it's height is 0mm from the print sheet.
What seems to fix this is to run the XYZ axis test again but I have no idea why the Z axis calibration messes up so badly.
I was promised that the devs will get in touch with me last week. Which did not happen.
And all the threads here seem to be ignored by Prusa - this is getting really disappointing, guys... At least, give us a life sign like "we're totally stumped, see your problem and working full throttle to resolve this"!
RE: Z and Y axis calibration problem
Just for reference, here‘s the video of what happens with my z-axis calibration.
RE: Z and Y axis calibration problem
Just wanted to post that I’m also having this issue.
I’ve tried reflashing the software, and been on with support. I can get it to print occasionally by doing a Z-Calibration and then “Auto-Home”, but that gives a whole mix of results and doesn’t always work.
Really hoping they can figure this out so I can have a usable printer again.
RE:
My newly assembled mk3.9/4 is homing too high (about 7cm) above the build plate as well.
I can get it to print by getting the hot end as low as possible before starting the print then it manages to actually home the z.
RE: Z and Y axis calibration problem
Looks like difference between the stepper-motors of the MK3S+ making 1.8 degree/step and the new motors of the MK4 making 0.9 degree/step. Wrong firmware or incorrect setting?
Can't verify myself, having only the MK3S+.
RE: Z and Y axis calibration problem
Looks like difference between the stepper-motors of the MK3S+ making 1.8 degree/step and the new motors of the MK4 making 0.9 degree/step. Wrong firmware or incorrect setting?
Yeah, I was suspecting something like that, too. However, the firmware auto-detects if it's running on a MK4 or a MK3.9 by fetching info about the stepper motors. This is so annoying since I had working printer which I ruined by spending 560 €…
RE: Z and Y axis calibration problem
So here is my latest troubleshooting and results:
I removed the trapezoidal nuts for both of the vertical motors that move the z axis, completely loosened the 4 screws holding the z axis motors in place and repeated the process of centering the lead screws in the holes in the top z axis rod mounts where the trapezoidal nuts are installed. Once I got the lead screws centered again, I reinstalled the trapezoidal nuts and tightened them in place. I then reattempted the complete first time calibration/initialization process and it competed successful without errors. I then tried the autohome process and that was successful. I then tried just a calibrate z axis process and that was successful. Initiated a meshbed level and that completed successfully. All good so far! Next I printed the test cube code that prusa support sent me and that printed just fine. I then printed another small part as a test and also success. This seemed great - then I turned off the printer and back on. When I turned it back on and attempted another test print, it started behaving oddly like the z axis was not calibrated again (it was doing the nozzle cleaning up in the air rather than against the build plate) and then failed. I attempted to do a z-axis calibration and it failed again exactly like it had in the past. I tried the complete calibration process and it failed again exactly as it has been… No calibration or reseting would succeed. So, I again removed the z-axis nuts from the lead screws and repeated the centering process and put everything back together and then powered on and retried the z-axis only calibration. That failed. So then I restarted the complete calibration process and that succeeded. Once that succeeded, I again tried the z-axis only calibration and that succeded. So next I attempted to print a test print but had a bit of a problem in that I was not getting good bed adhesion. The first layer looked pretty good but was not sticking like it should on the smooth plate (and this was using PETG which *should* stick too much on the smooth plate. After trying 3 times, really cleaning the plate well between each attempt to make sure there was nothing on it to interfere with the adhesion, the Z-axis suddenly started failing again. would not pass calibration and the full calibration would not pass either - fails on the z-axis every time just exactly as before about 2-3 inches above the build plate….
So, here is what I think is going on and I think this info needs get to developers or someone who has the ability and details to understand the code driving the hardware. I think the printer is measuring resistance to movement in the z-axis. Not via the load cell but I am guessing by the power draw of the z-axis motors and once it sees that power draw climb over a certain point, it interprets that as resistance to movement of the z axis and stops the movement at that point. Probably thinking the print head is hitting something. But in this case its not really hitting anything but just resistance. When I check, the z-axis moves just fine manually. So it seems that it is overly sensitive. I am wondering if it is coded to look at a certain power draw for a new motor and does not account for a motor that is 2 years year old because it is an update kit not new? I don’t know. Maybe it really is encountering resistance too high - maybe the new design z-motor mount is coming out of alignment enough to trigger the issue - I don’t know....
Subsequent to this testing, I installed the latest alpha version firmware and restarted the complete initial calibration cycle. It passed completely, and now I have printed about 6 test prints all with no issues. So fingers crossed this may be fixed.
RE: Z and Y axis calibration problem
When I turned it back on and attempted another test print, it started behaving oddly
This OTOH sounds to me like corrupted memory state, uninitialized variables or any other undefined behaviour in C or C++.
RE: Z and Y axis calibration problem
Wow, thanks for your extensive post and testing!
Subsequent to this testing, I installed the latest alpha version firmware and restarted the complete initial calibration cycle. It passed completely, and now I have printed about 6 test prints all with no issues. So fingers crossed this may be fixed.
Which alpha did you install (and where did you download it)? The 5.0.1 firmware which was released today did not change anything for me...
RE: Z and Y axis calibration problem
exactly what i think the z position is not known by the software i reset everything and its printing atm will try the firmware update also
RE: Z and Y axis calibration problem
https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v5.1.0-alpha2
RE:
Installed the 5.1.0 alpha2. Initial observations:
- without any hardware changes (like re-aligning the z-axes etc.), xyz-test ran straight through.
- the algorithm for xzy-calibration has changed: first step, the extruder moves all the way up, performs x- and y-calibration and last, it moves down to the print plate - moving slowly and waiting for data from the load cell instead of evaluating current from the z-motors which is not really reliable for the 3.9 build.
- currently, I'm printing.
What I have to check:
- z-axis and rod alignment
- behavior after a power cycle
- longer-term stability
What should be done by Prusa:
- release this alpha2 firmware asap
- make Prusa tech support aware of this problem and offer the alpha firmware as a solution (!!!). Unfortunately, first level support and also support by email was unaware of this problem and had no solutions.
- don't release the upgrade kit before the firmware has been fully tested. This is just a side not for the release of the upgrade kit to the MK5... 😉
RE: Z and Y axis calibration problem
Hallo,
ich war extrem frustriert nach dem Umstieg von MK 3s auf 3.9! Nichts ging mehr! z-Kalibrierung schlug regelmäßig fehl, ab und an aber schaffte ich irgendwie - nach allen möglichen Veränderungen- wieder einen Druck. Dann der nächste und schon blieb der Kopf in Z-Richtung nach ca, 2/3 der Höhe stehen! Wieder nichts. Zum verzweifeln!!!
Einspielen der Firmware v5.1.0-alpha2 und ich kann wieder drucken!
Allerding nicht bereits geslicte Projekte für MK 3.9 die zeigen einen Fehler der Düsenreinigung und das wars dann. Also STL/3mf Daten neu slicen und dann geht's.
Aber das kann's nicht sein!!! Auf die Lösung zufällig im Forum zu stoßen! Ich war kurz davor das Ding in den Müll zu werfen.
Hoffe , das diese Zeilen auch Entscheidungsträger lesen und schnellstmöglich ein offizielles Update kommt.
Hans