Thanks a lot for this. This is a really tremendous idea. I've hated sloppy hex bearing fits, and this seems like it should solve the problem.
We plan on replacing our hex bearings on our bearing blocks with these, and just turning down our hex shaft.
The 13.72mm bearing seems to be the perfect size. You still get plenty of contact area on the bearing (
http://content.vexrobotics.com/vexpr...-20141216.PDF), and it's still a hex, so you can throw a gear/sprocket on it, and not worry about the shaft breaking.
The clearance hole also lets us tap these for 1/4"-20's, but doesn't really weaken the shaft much.
This is probably the most excited I've been for an uncommonly sized bearing.