In this picture it is easy to see where the problems actually come from.
The washer is simply too big for the pulleys. These washers appear to be burnished, which is why the quality of the printed surfaces initially appears to be very good but gradually becomes worse. The bluing is lubricating, but wears off over time due to incorrect application and size. Increased friction occurs, which results in noise and surface defects. Which is why lubricating these areas also provides short-term relief.
The only option for a permanent solution is suitable spacers. These are significantly smaller and usually made of brass.
This means that only the bearing is supported and the actual roller runs freely and does not rub against anything.
It would be interesting at this point to know whether all the rollers are affected or just the belt tensioners. Has anyone else had experience here?
It is actually quite common to use ‘oversized’ washers on rollers like these.
These needle bearing stuff up really fast and really bad once dust and debris enters them.
I think you indentified a big issue, but IMHO it is not those washers, it is the roller.
The profile of the roller should be slightly less than this bearing, a bit under 1/10 of a mm.
Actually wondered since day one why Bambu would use Aluminium rollers here rather then PU ones.
While I was still working as a sparky and building machines we used (much bigger) belt rollers that had a hardened steel core and a PU profile for the belt.
Only required a smooth shaft bolt to work fine for many years and then a replacement only took minutes.
Even with those Aluminium ones and the wrong washers I suspect it comes down to cost saving measures.
Keep in mind the game works like for our old paper printers - EVERYTHING is a consumable and costs money to replace…
