I do have to appreciate Prusa Supports diligence in assessing the issues. Coming from a Science and engineering background I completely understand, the step by step approach. That said, I can also see why I read posts from customers about getting frustrated with it. I'll admit the length of time it took really was my fault as every ask from support required my time and the printer being out of use for a period. So there were weeks in my replies. Likely could have gotten to this point in less than a month. Anyway, will update here is the Y bearings resolve it. I'm skeptical about the motor but can't harm to go all in at this point!

I’ve managed to resolve/reduce the issue in the past by retuning belts, little adjustments here and there but was never 100% why it worked. I seem to have just prolonged or delayed a bigger problem 🤣 😭 

The toolhead never made the noise while moving by hand at the original 85hz belt target. Might try going back for a bit. 

Again so I’m not crazy, I’ve attached a video of me moving the printhead by hand. The variability in the noise at different position’s means that the noise is somewhat sporadic when I’m printing. When I lower belt tension into the 80hz and below range it moves smoother and doesn’t make these same racket. I have tried lubing the rod with no improvement

Hmm -- you seem to get the same noise whether moving in X or Y direction? I had misunderstood that before; thought it was during Y movements only. This makes the Y bearings a much less likely culprit, I think.

Can you isolate the noise to just one of the motors moving? I.e. if you move the print head at +- 45°, does only one direction trigger the resonances? 

Again so I’m not crazy, I’ve attached a video of me moving the printhead by hand. The variability in the noise at different position’s means that the noise is somewhat sporadic when I’m printing. When I lower belt tension into the 80hz and below range it moves smoother and doesn’t make these same racket. I have tried lubing the rod with no improvement

Video 4 - Moving by hand 

Just so I’m 100%, you’re referring to keeping these loose and the bolts holding the y rod block at the opposite end? I assume you do that movement prior to installing the xy on the rest of the frame? 

Yes, those are the mounting screws I had in mind. (Sorry, did not see your post before I went to bed yesterday.)

When you loosen and re-tighten the screws at the gantry's mounting bracket, as suggested by @hyiger, you let the gantry length adjust to the Y rod distance at that Y position. But if the Y rods are not parallel, the X distance will still not match once you move the carriage to a different Y position.

Having said that -- if you get bearing noises even with the screws still loose (i.e. when the carriage length can change "in real time"), something else may be at play here. Maybe the Y bearing was indeed damaged somehow and should be replaced, as hyiger suggested.

Posted by: @hyiger

 

Posted by: @wdlandry

Just so I’m 100%, you’re referring to keeping these loose and the bolts holding the y rod block at the opposite end? I assume you do that movement prior to installing the xy on the rest of the frame?

No, it would be the screws bolting the gantry to the Y axis bearing holders

https://help.prusa3d.com/guide/5-corexy-assembly_835522#844219

 

The four screws to where the belt is exiting in this photo. Loosen all four on both sides, slide the gantry back and forward several times then tighten. 

Posted by: @wdlandry

Just so I’m 100%, you’re referring to keeping these loose and the bolts holding the y rod block at the opposite end? I assume you do that movement prior to installing the xy on the rest of the frame?

No, it would be the screws bolting the gantry to the Y axis bearing holders

https://help.prusa3d.com/guide/5-corexy-assembly_835522#844219

The four screws to where the belt is exiting in this photo. Loosen all four on both sides, slide the gantry back and forward several times then tighten.