After the two first test prints I've ONLY performed phase shifting and input shaping calibration using the accelerometer kit I had, w/o any physical changes and the noise has gone! I now mostly hear the fans while sitting one meter from the printer. It's now more quiet than mk4s which it has replaced, like a magic..

Kudos to the engineers, I guess.

I found plastic bearing were better for my CNC project.

Is there anyone who has tested to place anti vibration plates on the sides of Core One or Core One L ?  

Have you tried damping the panels by touching them, and does it actually have a significant effect?

I think the consensus for the Core One is that it is preferred to damp the vibrations closer to the source. If the stepper motors excite resonances at certain speeds, try a new phase stepping calibration to see whether that makes the printer more quiet. If a panel rattles against the frame somewhere, try to re-seat the rivets in that area. If the noise stems from some other internal component that can rattle/vibrate, try to find and damp that. 

I find the vibration noise very loud from the metal sides of my printer and I was wondering if  the noise could be reduced
by fastening self adhesive bitumen plates on the inside of the printer. There is not much room in the Core One L though,
so it might not be possible.

Has any one tested this or somethis similar?

Hi all!! I can see this noisy-bed situation with the Prusa Core One is really frustrating, especially when you just want a smooth, quiet print. Often, the noise comes from vibration or uneven movement, so checking belts, bearings, and frame alignment can sometimes help reduce it. A few people have also mentioned that lubrication and making sure the bed screws aren’t too tight (or too loose) can make a surprising difference.

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Hope you find a good fix soon and get back to quiet printing

For quiet printing, just lubricate your Core One or Core One L with a generous serving of spam. 

So I tightened all my screws in the linear rails, pullys, frame, and this is after doing the belt tightening thing in the settings and it told me they didnt need to be tightened. Its still making this noise and im about to retire it because when it gets going fast it is so hard to listen to :/