RE: Failed Y-calibration of a new CoreOne
same problem 😀 pulley was wrong assembled :D:D:D thank you ! now its working!
RE:
Update!
Flipped the pulley on the x-axis motor, tuned the belts back up. Passed all calibrations first try!
Keychain and benchy printed successfully!
Thank you thank you thank you for posting your experiences!
RE: Failed Y-calibration of a new CoreOne
Any chance you took before-and-after pictures of the pulley? Or can you identify where at in the printer it is [I want to look at mine]. As it's working fine I suspect mine is fine - but still - I'd like to look at it.
Update!
Flipped the pulley on the x-axis motor, tuned the belts back up. Passed all calibrations first try!
Keychain and benchy printed successfully!
Thank you thank you thank you for posting your experiences!
RE: Failed Y-calibration of a new CoreOne
Incorrect installation.
Proper installation.
Here you go! Hope this helps!
RE: Failed Y-calibration of a new CoreOne
Holy cow. I managed to make the exact same mistake with my assembly. Can you please tell me what you had to do, to get to where you could flip the gear?
Thanks!
Flipped the pulley on the x-axis motor, tuned the belts back up. Passed all calibrations first try!
Keychain and benchy printed successfully!
Thank you thank you thank you for posting your experiences!
RE:
I'd had similar issues as others, but with a lot of collateral damage. I called support and they had me tighten the tensioner bolts. I broke both tensioners. Luckily, I did not order the Mk4S upgrade kit and I was able to print the parts in PETG. They are working now. I am waiting with baited breath for a replacement of these assembles on Printables. In my opinion, these parts should be made out of metal or use a design that will not allow over tightening and snap the plastic.
Now that the CoreXY is now back together again, I followed Martin's guide. The rails are aligned with no belt tension. However, when I begin to tighten the belts, the X tensioner sticks out of the holder, causing a gap on the Y side. I then stripped the printer down to the Core XY frame and rebuilt it. I did find that the X belt had slipped off the groove in the motor (fixed). This also might be causing issues with the Y calibration fail, Both belts should be in the center of the grooved gear.
I've owned Prusa printers since the MK3. They have been awesome machines. Dial them in and they just work. Starting with the 3.9 however, I started having random issues with Nextruder, I can bow rebuild a Nextruder in 2 minutes. Not a great skill to be proud of. I do believe that the products have been rushed out a little too early and needed some more time in the oven. My last gripe is about the instructions. The instructions require a significant amount of knowledge. Most of us have had many years of experience with bed slingers and know how they function and can troubleshoot. The coreXY is a different beast. What does not help is fully building the printer an THEN running the calibration tests. you could build the frame, build the LCD and run the calibration test BEFORE attaching all of the finish materials, that would have been much smarter.
I may pack the Core one up for a while until all of the issues are ironed out.
RE: Failed Y-calibration of a new CoreOne
So I figured I'd go ahead and give it a try. It was easy. I loosened the belts all the way (too far actually, be careful you don't lose the tensioner). Removed the X-motor-side acrylic and metal side panels. Turned the printer on its side, released the 4 motor attachment screws. I was able to remove the motor without losing any belts, flipped the pulley around, reinstalled the motor, redid the tension, and poof -- it passed on the first test.
Thank you for posting photos, I would never have thought to check this issue.
RE: Failed Y-calibration of a new CoreOne
Holy cow. I managed to make the exact same mistake with my assembly. Can you please tell me what you had to do, to get to where you could flip the gear?
Thanks!
Flipped the pulley on the x-axis motor, tuned the belts back up. Passed all calibrations first try!
Keychain and benchy printed successfully!
Thank you thank you thank you for posting your experiences!
Ended up being simpler than I expected thankfully!
I started by loosening the belt tension to almost nothing while keeping the tensioners connected. There was plenty of slack in the belts to remove the motor and reinstall like this.
I started loosening the screws for the x-axis mount and then realized I needed to pop off the left side panel and the top panel to really be able to get at two of the screws. As soon as I pulled the left panel off it was super easy.
Took those both off, finished loosening the screws holding the x-axis motor on. Very carefully raised the motor up and out of the belt. Flipped the pulley and then reverse of disassembly.
Then I made sure everything was still square, tensioned the belts, and it passed calibration first time! I've pretty much had the printer printing non-stop since then haha.
RE: Failed Y-calibration of a new CoreOne
Thank you so much for your help on this, we are good now!!
RE: Failed Y-calibration of a new CoreOne
Awesome! Glad I could help!
Happy printing!
RE: Failed Y-calibration of a new CoreOne
Me too!
I spent two days chasing a Y-Axis calibration fault and this was the root cause!
Thank you for posting this!
RE: Failed Y-calibration of a new CoreOne
Hi guys!
I received my printer yesterday and today i hit the same wall as you: y calibration fail. I looked over this topic for solutions, but i didn’t find the one i did - if i my solution is already pointed out i applogize, but my solution is this:
i dissasembled extruder again to a point where both belt ends are inserted and twisted back out - where manual says “leave 4-5 tooths sticking out” . I think that it’s absolutely a must that both belts have the same number of teeth out at both ends. If this is not true then one belt is longer than other and this y misalignment occurs. After equalizing both belts i have perfect y axis at 85 Hz on both ends.
I wish someone could verify that, but if it’s true this is something prusa really should mention in assembly manual with red letters…
RE: Failed Y-calibration of a new CoreOne
I think that it’s absolutely a must that both belts have the same number of teeth out at both ends. If this is not true then one belt is longer than other and this y misalignment occurs. After equalizing both belts i have perfect y axis at 85 Hz on both ends.
Hmm -- I don't see why equal belt length would be critical. If one belt is a bit longer than the other, its belt tensioner can take up the slack and you can still align both belts to the exact same tension, right?
I think it is more likely that you just did not get to the right tension and straight gantry setting in your initial alignment attempt, and had better luck when you redid it after the partial disassembly. In any case, glad to read that your printer works fine now. 👍
RE: Failed Y-calibration of a new CoreOne
If one belt is a bit longer than the other, its belt tensioner can take up the slack and you can still align both belts to the exact same tension, right?
True, but in this case this belt tensioner will be a bit more forward than other one (exactly like it is in our cases), because you must wind it more. And this leads to the fact that carriage hits one end sooner than other. Yes, you CAN set equal tension, but you loose left-right distance to carriage.
The point is that one belt "holds" left end and other belt "holds" right end. That's why they should be equal...
RE: Failed Y-calibration of a new CoreOne
True, but in this case this belt tensioner will be a bit more forward than other one (exactly like it is in our cases), because you must wind it more. And this leads to the fact that carriage hits one end sooner than other.
I don't have the printer in front of me right now, but am quite sure that this is not the case. If I recall correctly, the X carriage bumps against the outer, stationary part of the belt tensioner blocks. Only the inner part (which holds the idler) moves when you set the tension, and this part does not touch the X carriage.
RE:
I don't have it either, but i think you have the point on this part...only tensioner moves...
but still..i think it's like children's swing: if two ropes aren't the same length you're bound with a non-straight seat. You could compensate that with more tension on shorter rope (if we assume that rope can be tensioned). Same is here: you can compensate distance with tensioning, but then you're bound with non-equal tension.
I don't know, but moving too long belt one tooth solved so that both are equal this problem for me.
RE: Failed Y-calibration of a new CoreOne
Having unequal tension on the belt is the original method that prusa had for aligning the x/y axis if the gantry didn't hit the end stops at the same time prior to applying tension, so it will pull the system out of square, unless it pulls the system square (im not sure what the analogy would be swing wise, but you ropes might be different lengths but the tree branch they are attached to is also at different heights so your seat ends up level?). I feel like I should check my belt to see how many teeth are pulled through but my memory of putting together the extruder is filed under 'non trivial tasks' so maybe soon lol
RE: Failed Y-calibration of a new CoreOne
(... but you ropes might be different lengths but the tree branch they are attached to is also at different heights so your seat ends up level?)
True, but since metal base of where extruder is mounted is laser cut it should be very precise, so we can safely assume that "branch is perfectly level" 🤣
RE:
The belts do not have to be the same length. One being longer than the other just means you have less room for adjustment.
The tensioner on the longer belt will just move more before the slack is taken up and tension is built.
There are obviously limits - if the belt is too short it won’t reach the tensioner - if the belt is too long the tensioner will run out of internal travel before the slack is taken out and starts to tension.
Imagine you have a metal pole in the center of your room and you have two ropes tied to it. One runs to your right hand and one to the left.
If you want to pull both so that they’re the same tension and you grab them from the very end - you can still tension them both the same without moving your feet/body and just your arms so long as the longer rope isn’t longer than you can reach without moving your feet/body.
You could easily apply the same force to both even if they were say 1’ different in length - one arm would just be further way from the pole than the other but your body wouldn’t move. In this analogy your arms are the internal tensioners and your body is the outer shell of the tensioners.
Same idea with the belts in the core one and the tensioners. So long as the tensioners can adjust far enough to put the belt into proper tension - the length of the belt itself doesn’t matter.
Take it another logical step - if the belts were required to be EXACTLY the same length nobody would reasonably be able to consistently tension both belts to 85 hz across hundreds or thousands of production printers.
Even further - building a CoreOne or replacing a belt would be a nightmare in trying to make sure the belts were exactly perfect.
RE: Calibrazione Y fallita di un nuovo CoreOne
Problem solved: the filament sensor on the right side of the printer was touching the right bearing, causing the calibration to fail. I removed the sensor and the calibration completed successfully without issues. If you notice the motor struggling near the end of the calibration, try gently pushing it toward the back — the issue is likely the sensor making contact with the bearing and blocking the movement.