I think they're supposed to be at 45 degrees to the side forces, but not absolutely sure.

Yes , they are! 

Posted by: @conrad-2

Just curious about something. On the factory linear bearings you removed, how are the ball races aligned? I think they're supposed to be at 45 degrees to the side forces, but not absolutely sure.

I'll take a look at the dismantled bearings.

Now I'm going to take a VFA test.

Yesterday, I conducted another VFA test with the two slide bearings.

PETG Black from Bambu Lab. I will have a glossy PETG available for testing again tomorrow. I believe it is still evident that the waves have not improved significantly.

As has already been mentioned here several times, the wave spacing is exactly the same as the tooth spacing of the GT2 pulley. Nice to see at the 30-degree test week.

My VFA test ranged from 50 to 150 mm/s in 10 mm/s increments.

Front and back - 90 degrees

Front and back - 0 degrees

Front and back - 30 degrees

Front - 60 degrees

Posted by: @huggypanda

Awesome!  What is that bearing material, delrin?

It's not Delrin, from what I've been able to figure out, it's a nylon base modified with PTFE and solid lubricants.  

"the problem is caused by manual speed adjustment, so I recommend sticking to default print presets to achieve optimal results."

I've been working with prusa support in parallel to see if they had any suggestions.  They had me do a test print of a 30mm cube with perimeters at ~55mm/s and of course it printed perfectly, so they closed the ticket saying:

"the problem is caused by manual speed adjustment, so I recommend sticking to default print presets to achieve optimal results."

... as if that isn't the first thing I tried.  Oh well.  Guess we're on our own.

Posted by: @jan-d-slay

Hello everyone.

I have now read various topics in the forum and on the Internet and have installed a plain bearing in the Y-axis.

I personally find the result impressive.

https://www.printables.com/model/1602328-prusa-core-one-resonance-noise-eliminated-with-sli

Now I'm going to take a VFA test.

The Printables headline talks about "Replacing the linear bearings on the MK4S", which I found a bit confusing. Is that meant to refer back to an already proven solution in the MK4S? Still it might be better to mention the Core One explicitly right up there.

Hello, Jürgen. Thank you for pointing that out! I have corrected it—my hand was quicker than my brain could check it. :-)

Interesting! I might (attempt to) print these out of POM. If that doesn't work, I also have a roll of Igus i150 I haven't found a use for yet. 

That would be very interesting for a comparison.

Would PC or nylon also work in this case?

Posted by: @jan-d-slay

Hello everyone.

I have now read various topics in the forum and on the Internet and have installed a plain bearing in the Y-axis.

I personally find the result impressive.

https://www.printables.com/model/1602328-prusa-core-one-resonance-noise-eliminated-with-sli

Now I'm going to take a VFA test.

Interesting! I might (attempt to) print these out of POM. If that doesn't work, I also have a roll of Igus i150 I haven't found a use for yet. 

I have now read various topics in the forum and on the Internet and have installed a plain bearing in the Y-axis.

I personally find the result impressive.

https://www.printables.com/model/1602328-prusa-core-one-resonance-noise-eliminated-with-sli

Now I'm going to take a VFA test.

Nice! I am not bothered by noise (yet), but can't wait for your VFA results!

The Printables headline talks about "Replacing the linear bearings on the MK4S", which I found a bit confusing. Is that meant to refer back to an already proven solution in the MK4S? Still it might be better to mention the Core One explicitly right up there.