608 Bearing using BBs

In 1999, I had a BB rifle and bought a box of 6,000 BBs. I didn't use all of the BBs, but I'm glad I kept them around! I needed some 608 bearings to make some additional filament rollers, but all of the bearings I found online didn't work well. This design uses standard Daisy BBs, which are 4.40mm spheres. For those unfamiliar with 608 bearings, the measurements are as follows: 22mm outside diameter, 8mm inside diameter, & 7mm thick.

I recommend trying the tight tolerance version first. If you print the tight tolerance version, you'll need to pause the print at 4.60mm, insert 10 BBs, then resume the print. If you print the loose tolerance version, pause the print at 4.80mm. The bearing works well and rolls effortlessly. 

The only downside is that they're louder than 608 ball bearings, but you can make them quieter by putting some white lithium grease on the BBs after the print is complete. I used the grease that came with the printer.