Failed Y-calibration of a new CoreOne  

RE: Failed Y-calibration of a new CoreOne

Thank you for checking! Good to know that the Prusa app does a good job with the frequency measurement.

So maybe the build technician in the Prusa factory was using some other metric to set the belt tension, which systematically deviates from the frequency measurement? Maybe some force-over-distance gauge, or maybe just his "calibrated thumb"? 😉 

RE: Failed Y-calibration of a new CoreOne

When we fit new belts to machines, we always over tension them from new as they will relax, but these are steel wire embedded timing belts, and we never drop the tension lower.

These belts are different and even support state to drop all tension then tighten to the correct frequency reading, so maybe the over tensioning is done on purpose ? but I really don't know in this particular case. Maybe someone from PRUSA could explain?

What I do know is after I have done all my pre-flight checks so to speak, the printer is printing beautifully with the supplied roll of prusament PLA. Even 65 Deg Overhangs have come out spot on. Next step PETG

So far very pleased with this printer.

RE: Failed Y-calibration of a new CoreOne

Just wondering if any more development on this front? Whilst i am still awaiting my CoreOne, I sincerely hope Prusa has addressed this issue?

Have recent (last 2 weeks) owners experienced this issue?

Thank you

RE:

I just got a replacement for my first one.

first one was heavily non-squared and went back, i received a new one 2 hours ago and it keeps failing on y calibration.

I don’t think the problem is on the printer but in assembly qc, never got 2 flukes in a row. I’ll wait until beta test phase is over to buy it again.

RE: Failed Y-calibration of a new CoreOne

thank you for the answer! btw when do you think that beta phase will be over?

RE: Failed Y-calibration of a new CoreOne

Usually after some months after release: software bugs get fixed, hardware revisions come out (documented if big enough, undocumented if not) but most importantly quality control becomes decent again after the initial rush.

For sure I’m biased but at the moment, is a mess

I had this issue today. It was caused by shipping damage in my case.

Self test failed Y-Axis test like you all.  Upon closer inspection I noticed there was a big dent in the outside of the housing and this was causing the Y-Axis to collide with the wall of the printer when it tried to traverse beyond half way!

Check your printer for damage, I think Prusa's shipping box isn't so robust for international shipping in this case.

This is where it was colliding on the inside:

Re: I had this issue today. It was caused by shipping damage in my case.

To clarify, Prusa is sending me a replacement Core One because of the shipping damage.  I do wonder though if some of your axis alignment issues are coming from minor handling damage that isn't very obvious when casually looking at the printer.  For example: Maybe that angle started off as 90 degrees.

RE: Failed Y-calibration of a new CoreOne

Mine arrived in a perfect box, not a scratch or dent anywhere, not a mark on the printer, it still does the headbanger game a bit more persistently now after a week of use. It failed once on day one, I tuned belts which where a bit loose and added some grease as there where a bit of rough spots when I moved the head manually, I only did a visual squareness check for gaps so far. Since then it behaved ok but is degrading last few days. It did something funny today, while it was headbanging before a print I got a crash detection, while I was trying to figure out what happened it just taped the ends once and continued to start the print.

RE: Failed Y-calibration of a new CoreOne

I just checked and rectified the two angle brackets from my newly received kit. It takes much less force than I expected: Supporting the small bracket arm in a bench vise, one can easily bend the other arm by hand; gentle finger force is enough.

So I feel better now about Prusa's advice to bend the brackets while they are installed in the printer (after loosening the belts and the opposite bracket). The forces acting upon the Y bearing will most likely do no damage to it.   

RE: Failed Y-calibration of a new CoreOne

I agree, LM10LUU are given for 1100N of static load. You could basically hang yourself to the bearing without damaging it.

It's a random spec found at Misumi website, but it gives an idea.

RE: Failed Y-calibration of a new CoreOne

Posted by: @jurgen-7

I just checked and rectified the two angle brackets from my newly received kit. It takes much less force than I expected: Supporting the small bracket arm in a bench vise, one can easily bend the other arm by hand; gentle finger force is enough.

So I feel better now about Prusa's advice to bend the brackets while they are installed in the printer (after loosening the belts and the opposite bracket). The forces acting upon the Y bearing will most likely do no damage to it.   

Fortunately, the brackets themselves are not what provides rigidity in the XY plane.  The rigidity actually comes from having equal belt tension.  The brackets do need to be bent accurately so as not to interfere with balance of tension but once they’re aligned, the rigidity should not be an issue.

RE: Failed Y-calibration of a new CoreOne

Posted by: @jurgen-7

I just checked and rectified the two angle brackets from my newly received kit. It takes much less force than I expected: Supporting the small bracket arm in a bench vise, one can easily bend the other arm by hand; gentle finger force is enough.

So I feel better now about Prusa's advice to bend the brackets while they are installed in the printer (after loosening the belts and the opposite bracket). The forces acting upon the Y bearing will most likely do no damage to it.   

Thank you for checking and reporting!

Our printer is working great with the shims/underlays. But maybe one day I may remove them and bend the brackets to their exact angle. One by one - with loosened screws on the opposite bracket.

@Jurgen-7 good luck with your kit build!

RE: Failed Y-calibration of a new CoreOne

Well, count me in as another with this same problem. 😕

Roughly 20 hours spent Friday/Saturday enjoying assembling my kit, and now stuck with this. 

Frame/gantry all seem perfectly straight and undamaged. Must have backed off and retensioned the belts 20-30 times, no better. Print head just clatters about at the front RH corner, and after a few minutes the machine reboots to this same error.  

Not going to lie, after now reading the tweaks and “fixes” for this problem, by bending/shimming stuff or tensioning the belts differently, I’m starting to feel that we’re beta testing this machine. 

Will try and contact support today for advice, though at the moment I’m tempted to just ask for a return. 

RE: Failed Y-calibration of a new CoreOne

Posted by: @largriff

 Fortunately, the brackets themselves are not what provides rigidity in the XY plane.  The rigidity actually comes from having equal belt tension.  The brackets do need to be bent accurately so as not to interfere with balance of tension but once they’re aligned, the rigidity should not be an issue.

In theory that's how it should work, but I suspect that if one disconnected one of the brackets, the print quality would get worse if it even got past homing. Want to give it a try? 🙂

RE: Failed Y-calibration of a new CoreOne

Posted by: @bigscotal

Frame/gantry all seem perfectly straight and undamaged. Must have backed off and retensioned the belts 20-30 times, no better. Print head just clatters about at the front RH corner, and after a few minutes the machine reboots to this same error.  

Not going to lie, after now reading the tweaks and “fixes” for this problem, by bending/shimming stuff or tensioning the belts differently, I’m starting to feel that we’re beta testing this machine. 

Will try and contact support today for advice, though at the moment I’m tempted to just ask for a return. 

Sorry to read about your frustrating start with the new printer! Based on my own experience and the reports in this thread, this should be a fixable problem and hopefully will not be the driver for giving up on your Core One.

You did not state it explicitly, so please allow me to ask: When you have the motors powered off and manually push the X gantry towards the front (pushing it at its center), does it reach the left and right end stops at the same time? And does it stay "in touch" with both end stops when you stop pushing?

If that should not be the case, while the belt tension is equal in both belts, the gantry will need to be squared (trammed). After I experienced how relatively soft the angle brackets are, I no longer feel bad about bending things in place, while installed in the printer. Loosen the belts and gently bend the gantry. Push it back and forth again to check whether it reaches the two end stops at the same time.

Most accounts here suggest that there is a causal relationship between the non-squared gantry and the printer's hunting for the end stops. Hence, fingers crossed that you can get this problem "squared away"!

RE:

Gantry seemed absolutely fine when pushed fully forwards/backwards, and bumped up against the ends uniformly at both sides. I’d read about this, so had a good check to make sure all was well.

Also tried the belts at exactly 85/90/95 Hz to see if that helped, but no  

Spent an hour or so on a chat with tech support this morning, going over the same ground, adjusting belts, making sure the extruder was moved all round the plane to ensure belt tension was distributed evenly. Sent photos and videos to show all of this, but no further forward. 

End result is that I have now requested a return I’m afraid. I’m confident in my build being correct, and if the machine can’t/won’t work as designed and manufactured, then as I see it, there’s a problem. The posts on here relating to manually bending the two metal brackets, or adding shims, just make me feel that theres an underlying design issue. It’s too expensive a machine for that to be the case. 

On the bright side, I did enjoy the build process, and for anybody that wonders, yes, the full printer fits back in the kit box if you just remove the door! 

Posted by: @jurgen-7

Posted by: @bigscotal

Frame/gantry all seem perfectly straight and undamaged. Must have backed off and retensioned the belts 20-30 times, no better. Print head just clatters about at the front RH corner, and after a few minutes the machine reboots to this same error.  

Not going to lie, after now reading the tweaks and “fixes” for this problem, by bending/shimming stuff or tensioning the belts differently, I’m starting to feel that we’re beta testing this machine. 

Will try and contact support today for advice, though at the moment I’m tempted to just ask for a return. 

Sorry to read about your frustrating start with the new printer! Based on my own experience and the reports in this thread, this should be a fixable problem and hopefully will not be the driver for giving up on your Core One.

You did not state it explicitly, so please allow me to ask: When you have the motors powered off and manually push the X gantry towards the front (pushing it at its center), does it reach the left and right end stops at the same time? And does it stay "in touch" with both end stops when you stop pushing?

If that should not be the case, while the belt tension is equal in both belts, the gantry will need to be squared (trammed). After I experienced how relatively soft the angle brackets are, I no longer feel bad about bending things in place, while installed in the printer. Loosen the belts and gently bend the gantry. Push it back and forth again to check whether it reaches the two end stops at the same time.

Most accounts here suggest that there is a causal relationship between the non-squared gantry and the printer's hunting for the end stops. Hence, fingers crossed that you can get this problem "squared away"!

 

RE: Failed Y-calibration of a new CoreOne

Posted by: @altaic

Posted by: @largriff

 Fortunately, the brackets themselves are not what provides rigidity in the XY plane.  The rigidity actually comes from having equal belt tension.  The brackets do need to be bent accurately so as not to interfere with balance of tension but once they’re aligned, the rigidity should not be an issue.

In theory that's how it should work, but I suspect that if one disconnected one of the brackets, the print quality would get worse if it even got past homing. Want to give it a try? 🙂

True, you can’t get away with removing a bracket, of course, but I bet you could replace it with a hinge.  The belts provide the cross bracing to keep the gantry square.  The brackets are over-constraining.

RE: Failed Y-calibration of a new CoreOne

@BigScotAl, I know it must be frustrating.  I feel your pain!  Just a question for you before you send it back.  Can you take a look at the tension adjustment pulleys and screws?  Are they both pretty evenly adjusted, or is one substantially (> 2-3mm) more extended than the other?  If so, you might be able to reattach the belt ends a notch or two, as needed, to get them balanced.  Just speculating; I’m still waiting on mine.

RE:

Also tried the belts at exactly 85/90/95 Hz to see if that helped, but no  

Have you tried anything less than 85?

I have also fitted the kit in the last few days. It is true that sometimes, when it recalibrates the axle, it hits the stop more often and for longer. But my MK4S does that too.

Also printed without any problems. Before the input shaper measurement, I corrected the belts again as they were apparently a little too loose. From then on, the problems started like yours. A new measurement showed that the tension was slightly too high (approx. 89), so I set it back to 85 and since then there have been no problems at all. Perhaps there are deviations in the measurement with different devices. Perhaps try small steps with less tension. A few Herz can make a difference. Working or not was 1/8 of a turn on the adjusters for me.

Don't forget to switch off the engines or switch off the printer when adjusting the belts!!!

I think you made sure that everything runs very smoothly before fitting the belts?

If reducing the tension doesn't work, I would try something else.I would loosen the Y-axis fastenings very slightly and try again.  Maybe there is a little tension after all.

Don't give up so quickly, it's worth it. My Core One prints really well.