Threadless Ball Screw. No More Backlash

This is a type of ball screw I read about at least 20 years ago in a technical trade journal. I have also seen it used in some linear actuators. Some advantages of being thread-less is that there is no backlash, no expensive threaded rods, and if you exceed the force threshold the unit simply slips without damage. A perfect combination for 3D printing.

7/6/13 - I have added a picture of a double unit.
7/7/13 - Added bearing mount with 10 deg angle. 4.14 mm per rev.
7/18/13 - Added bearin