Printer friendly caged roller bearing

# A *really* printer friendly roller bearing

Print-in-place mechanical things are fascinating, especially things that can actually be used for something. Maximum points for things that can't be manufactured any other way!

A ready assembled ball bearing fits all of this, but sadly it's not really possible to 3d-print a ball bearing that is anything more than a curiosity, since the balls can't be round if they are to stay in place while being printed. But roller bearings should be possible, and indeed there are lots of designs for print-in-place roller bearings here.

I have tried quite a lot of them, and one thing is immediately clear, the rollers have to be caged. Free running rollers have too much friction as the rollers are grinding against each other, and they will not roll straight causing a very jerky motion while being under load.

A good cage should keep the rollers running straight on the races, and that should in theory get rid of the jerky motion. I have tried a cou