Printable 608 bearing (filament rollers)
by Corona688, published
 Please see the remix for a more finalized version.
 The v2c STL file is the one to print. The small top piece fits much better than v2b.
I liked noreway's design, but the idea of using an extruder to print small plastic cylinders out of reels of small plastic cylinder struck me as kind of funny.
So I tightened up some tolerances to fit 2mm filament, loosened others so I could print on my makerbot x2 without cleanup. I've also included a pegboard thing to help make perfect 3mm-long cylinders.
The result works. I won't claim it's perfect, but I'm getting better results than gear bearings with mine.
Your ability to make this work will depend on your ability to cut and manipulate dozens of tiny rollers out of ABS filament. Fill each of the holes on the jig with slightly more filament than needed then sand them flat. This is NOT a waste of time! Pointy rollers vs flat ones is the difference between a bearing that goes crunch vs one that goes roll.
Depending on the tolerances of your printer, the jig may be slightly too short or tall. Scale as appropriate.
Stick maybe 2 dozen on a piece of scotch tape, and curl it around the inside of the tall large piece. Insert the tall core, and add more rollers until it's full. Glue on the short large piece with ABS cement, carefully remove the tape with needlenose pliers, glue on the short center piece.
A drop of oil inside goes a long way.