Didn’t work for me unfortunately. I tried compressed air on all the idler pulleys (I found 10), did a spray of IPA, adjusted belt tension.
not sure if belt rubbing is the issue, or if there are other pulleys.
Is it ok to grease the top/bottom edges of the belt?
update:
it seems it is ok to apply grease Horrible Squeaking, possibly ball screw bearing - #7 by soulrider911 but i don’t fancy doing it, it will end up full of dust and bits of filament.
DO NOT APPLY GREASE TO BELTS
I mean, you can do what you want with your machine, but the petroleum in grease will make the belt break down faster and it will attract dust and debris.
I’m sorry my fix didn’t work for your. Please let me know when you’ve figured it out
The squeaking is from the belt rubbing on the idler pulley edge. Grease or any other lubrication only masks the problem it does not solve it. And If you are lucky you will need to replace only the belt far before it would be necessary.
Main cause for the squeaking is misalignment of the pulleys. And only solution is to align them properly.
If you really want to get rid of the squeaking check this video applies also for P1S and P1P:
X1 mainenance
Watch from 12 minute onward. This solves squeaking on the XY.
In other hand I had the squeaking issue on the Z axis belt also which is not so “easy” to fix.
I did some sketchy adjustment by shimming the pulley on the tensioner to get the belt running on pulley correctly and the squeaking is gone. I posted this “fix” with pictures and video before and after on Facebook in Bambu Lab Official User Group
After adjustment belt is stil moving on the pulley up and down, but it does not get stuck on pulley edge and make the squeaking noises… This is far better solution then greasing the pulleys belts as Bambu Lab suggests.
This is a really good post, thank you. I’m an engineer - what you say makes sense.
Until the squeaks started, I had been enjoying my experience of ‘everything just works’ without having to think too much about “how” it works.
I have YX and Z squeaks now. The video is useful so I’ll have a look through the other ones. Do you have a photo or smth else on your Z axis shimming as I’m not on facebook.
Sorry did not take detailed pictures, primarily was for me and was anxious to see if it works. And not to be a how to guide since the “fix” is quite sketchy in my opinion but it works.
Idea is/was to tilt the pulley on it’s axis to force the belt to move more in the center of pulley.
First picture: On the tensioner part itself I taped 3 layers of the electrical tape - if thicker the pulley console/tensioner does not fit in the slot anymore and the spring has not enough power to move it and tension the belt.
Tape must begin on the vertical line blue marked on side of the console towards and it ends 2-3 mm before the center point of the pulley - the shaft, to get the tilt of the console and pulley.
Second picture: The bracket that fits over the pulley console/tensioner - fixed with 3 screws. Has added 3 layers of tape as marked on the picture and one mM3 washer on the bolt that fixes the tensioner pulley after the spring tensions it. This bolt by design is off center on the tensioner so the washer pushes the tensioner in the direction I needed to get the pulley tilted in correct way.
Last picture only shows the grime on pulley that amounted in 200 hours of printing… If i or someone else would be adding grease or oil here I’m 100% the belt would break or turn on itself in future during printing. Making a lot of problems to fix and clean it + traming the bed…
When working on the Z axis I screwed back the bed on position as it is with new printers when you get them delivered from factory in order to minimize or prevent getting the bed traming off. So it was quite some work to find the make the shimming correct in order to have the belt move towards center of pulley. It took me cca 1,5 - 2 hours between shimming testing and repeating the steps until the squeaking was gone. YX was much easier 
Here are links to Youtube (not sure if the videos can be attached here). I trimmed them a bit but still quite large files. In case if someone wants to hear the squeaking noise :
You can see on videos pulley on lead screw - some fine craftmanship. And all 3 of them are like this.
https://youtu.be/OFRlEpf9FNM Z axis after adjustment.
https://youtu.be/Pa1LBRjCwsA the squeaking sounds during bed levelling before alignment X Y Z axis
https://youtu.be/IkPltPbN_Fk And the noises after the alignment. The squeaking is gone, no lubricant used for this
brilliant - thanks for sharing this.
I think this description will make sense when I have the pulley and cover in my hand:
Blockquote
“Tape must begin on the vertical line blue marked on side of the console towards and it ends 2-3 mm before the center point of the pulley - the shaft, to get the tilt of the console and pulley.”
I’m in the middle of a printing blitz right now so will have a go at z adjustment when I finish. It’s nice just to know there is a solution!
No problem hope it helps. Perhaps i manage to get a cad file of the tensioner then i could possibly design and print one with adjustable angle. Or better yer Bambu would take up on them provide users with step 3mf or stl file and anyone who wants can print it
i’ll let you know how i get on