RE: Failed Y-calibration of a new CoreOne
Update some 2.5 months later.
I did some maintenance on my printer, just cleaning, lubrication and checked the belt tensions, they have dropped to 74 Hz! so arrived new set at 107Hz, I adjusted down to 90Hz and now after the printer has been in use they are at 74Hz.
I didn't expect this much stretch!
I have adjusted the belts back up to 86Hz.
You may want to check yours.
Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.
RE: Failed Y-calibration of a new CoreOne
I believe there is a step in the assbly manual for the kits to check for binding on this axis. One of the comments was a string of people getting caught by the cable from the filament sensor.
RE: Failed Y-calibration of a new CoreOne
It’s quite a long belt. If it stretches just a bit it’s enough to drop frequency for this much. And, to be honest it’s to be expected. Every new thing does that. In fact, i think tension check should really be performed regularly, i’d say every couple of months or so. It’s so much easier to readjust tension than on mk4 that it really shouldn’t be a problem.
RE: Failed Y-calibration of a new CoreOne
Hello,
I got the same problem on my Core One kit ... Finally, I figured out that the Y motor pulley was upside down ... X was great because I double checked it and then ... do the same reverse mounting on the Y 😶
RE: Failed Y-calibration of a new CoreOne
i also had the pulley on the x-axis inverted, thank you to all the posters! I was able to eventually get the X and Y axis checks to pass (the belt tuner app still only works once in thirty tries). I am currently struggling to get it to load filament without going into the same sort of spastic Y-axis check.
RE: Failed Y-calibration of a new CoreOne
I Just did my conversion and also ran into this Problem, after bending the x Axis straight I still wasnt able to get it done. Bit this thred helpes a lot.
My other Problem was that one of the belts wasn't on the teeth of the Motor, It was the left Motor in the Back, so Check both Motors If the belts are running smoothly in there. Also If you fully loosen your belts this Problem could also happen. It's noe running smoothly.
RE: Failed Y-calibration of a new CoreOne
So I had this issue as well. It wasn't a cable problem, my belt tension tuning was correct and I even checked it against another sound analyzing app. Mine would go to the front right corner, then do a series of touches to the front, the right side and a diagonal bumping back and forth. I made sure all the bolts were tight and it wasn't ramming anything and just told it to print. Seems to work well. I printed a quality check with overhangs and critical dimensions to measure and everything seems great. The only thing I can think of is if something is out-of-square somewhere in the frame BUT IF THE CALIBRATION CAN TELL ME THAT IT SHOULD BE GIVEN AS A RESULT OF THE TEST.
If you calibration software checks something and it fails, it should report to the user what failed and why! Who thought it was a good idea to have the machine return NO INFORMATION to the user?! When I hear "Y-axis calibration failed" I think of: distance, endstop sensors not triggering, a problem with the motor, a problem with some sort of motion controller, an error in a sensor or a feedback system.
TELL
US
WHY
IT FAILED
Please.
RE: Failed Y-calibration of a new CoreOne
i also had the pulley on the x-axis inverted, thank you to all the posters! I was able to eventually get the X and Y axis checks to pass (the belt tuner app still only works once in thirty tries). I am currently struggling to get it to load filament without going into the same sort of spastic Y-axis check.
I had the same problem, were the instructions incorrect at some point? I actually remember catching that I'd put the Y-axis pulley on upside-down, it's just weird that I still made that exact same mistake.
RE: Failed Y-calibration of a new CoreOne
I had the same problem, were the instructions incorrect at some point?
No, I am pretty sure they were correct right from the start. My Core One kit was pretty early in batch 1 (shipped April 1st) and the instructions were fine. I think it's probably due to assembling the Y pulley "on autopilot", assuming that it's the same as the X pulley which was mounted in the step just before.
RE: Failed Y-calibration of a new CoreOne
The instructions are exactly correct, but it didn't match with my intuition. The worst part is that after seeing the other post, and wanting to investigate, I tore down that motor, saw I had the problem, and remounted the pulley in exactly the same way as I had it previously! After that, I made myself match the pulley & motor to the picture, to make sure that I didn't fool myself.
RE: Failed Y-calibration of a new CoreOne
I had the same problem, were the instructions incorrect at some point?
No, I am pretty sure they were correct right from the start. My Core One kit was pretty early in batch 1 (shipped April 1st) and the instructions were fine. I think it's probably due to assembling the Y pulley "on autopilot", assuming that it's the same as the X pulley which was mounted in the step just before.
Since the instructions are still on v1.0, that sounds reasonable. Interestingly I managed to get the spacing correct but got both cogs upside-down from the images (fixing one immediately and the other at the end of the build during calibration). That step must the the 165th step (I counted 330 actual steps, correct me if I'm off), as I feel like it's cursed.
RE: Failed Y-calibration of a new CoreOne
Same with me: 2 broken screws and 2 times reassembled already finished printer to the x/y axis because of the failed tensioning process. There is still some work for Prusa to deliver good kits of the Core One!
RE: Failed Y-calibration of a new CoreOne
I had the same issue after the assembly of my kit. My pulleys are mounted correctly. Sometimes it would home after at least 2min, sometimes not. I could see when pulling the X-Axis all the way forward that both sides didn't hit at the same time. I tried to align everything by bending back the metalbrackets. That was unsuccessful but the trick is to losen the belt tension all the way bend it back while constantly checking if both sides hit the end at the same time and when retensioning the belts going bit by bit while tensioning both belts at the same time. That worked a bit better but the printer still took for ever to home and calibrate. I tested again if both sides hit the front at the same time and they didn't. So my solution was to adjust the belt tension on the right higher until both sides hit at the same time. I'm now on 85 on the left and 107 on the right.
RE: Failed Y-calibration of a new CoreOne
So my solution was to adjust the belt tension on the right higher until both sides hit at the same time. I'm now on 85 on the left and 107 on the right.
I also had the issue, that the gantry hit both stops perfectly in-sync without belt tension, but didn't with both belts at exactly 85 Hz.
There's probably some tension, even when the belts are completely slack, simply from the belts stiffness/bouncyness.
My solution was different though: I tuned both belts to 85 Hz, checked the gap, made both belts slack and counter-bent the gantry so a gap was on the opposite side of where it was with tuned belts.
3 loops of this and I got both stops in-sync with both belts at 85 Hz.
Just to have calibration issues anyway.. But making the right tensioner a tiny bit tighter and towards 86 Hz solved it.
Important: always check this with the "Auto Home" from the LCD Screenr - > Control - > Auto Home and without pre-heating!
The flaky loadcell, when the heater is active, can also cause issues for the Y-axis calibration! So I added the M104 S0 line not only before the G29 commands (Nozzle cleaning and MBL probing), but also before the G28 command (Homing).
RE: Failed Y-calibration of a new CoreOne
I'm now on 85 on the left and 107 on the right.
As i mentioned above, I've had very similar different tension numbers to work correctly, but after i mounted both belts to exactly same length i have both belts at 85 and it works perfectly. I know it's quite a work, since you must disassemble practically whole extruder unit, but it works. I just can't live with the feeling that i have so much different belt tensions...
RE: Failed Y-calibration of a new CoreOne
I think your gantry stops are synced, because you "worked on the belts" and not because they have the same amount of teeth clamped at the back of the print head. Physically, it absolutely doesn't matter, but while working to achieve this, you probably stretched the belts and bent the brackets.
Nothing wrong with it, just a happy incident 😀
RE: Failed Y-calibration of a new CoreOne
Here's a remedy for the failure of the Y calibration:
1. It's caused by a misalignment of the Y axis with respect to the X axis.
2. The remedy is to carefully and gently bend the X axis bar, using details provided here: https://arachnoid.com/3D_Printing_Prusa_Core_One/index.html#Core_XY_Axis_Alignment
3. Belt tension is entirely independent, and you should not try to correct the Y axis issue issue by changing belt tension.
4. A successful conclusion has both belts set to 85 Hz and the Y test should pass.
I hope this helps -- it solved the same issue on my printer.
RE: Failed Y-calibration of a new CoreOne
TLDR: check Belt tensioner pully is fully within the housing and not coming into contact with the nozzle assembly during testing
I had a Y belt calibration failure on first startup after i assembled it myself.
fixed issue: too much Y belt being consumed by nextruder holder, this caused the 3D printed Y belt tension pully block to be about 2 mm past the 3D printed belt tensioner (housing). tensioner pully was originally fully within the pully housing but during tuning, the belt was loosened to achieve the correct tension, causing it to pass the edge of the housing.
disassembled hot end assembly, removed some belt from the nextruder holder, reassembled + retensionsed, tensioner pully well within the tensioner, Problem solved
RE: Failed Y-calibration of a new CoreOne
Just a heads up: I had approximately 5mm space on one side which was kind of possible to compensate by different belt tensions on left and right side but calibration of the Y axis would fail. It turned out I did mount the X axis pulley the wrong side (teeth further from the motor instead of closer). After reversing it, it was aligned perfectly.
The step that needs to be double-checked is https://help.prusa3d.com/guide/5-corexy-assembly_835522#843284.
RE: Failed Y-calibration of a new CoreOne
Hello everyone,
Unfortunately, I’ve had a disappointing experience with my pre-assembled Prusa printer. I specifically chose the assembled version and paid an extra €349 expecting a fully tested, ready-to-use machine. However, I was let down right from the start.
The printer had about 8 mm of play on the front left, which caused the homing process to fail and the printhead to crash violently into the frame. This kind of issue is unacceptable for a pre-assembled unit.
I contacted support and asked Viktor for a refund of the assembly fee, but this request was denied. I will now return the printer, but I have to cover the return shipping myself, which is very disappointing—especially considering I chose Prusa for their supposed quality and customer support.
These were the issues with my unit:
About 8 mm of mechanical play on the front left side
Homing process fails, printhead crashes into the frame
LCD screen is faulty or unresponsive at times
Firmware was outdated upon delivery
All timing belts were overtightened
The right timing belt adjustment screw is stuck and cannot be turned
It's frustrating to receive a machine with multiple defects despite paying extra for a professional assembly. Not every user wants—or is able—to tinker with a brand-new printer, especially when paying for convenience and reliability.
I truly hope Prusa takes this kind of feedback seriously and improves quality control and customer service in the future.