[InFlight]

I really haven't figured out any real advantage to thunder-hex for teams that already have a lathe and can custom machine any shaft that they might need. Vex does sell 13.75 mm bearing to go with the thunder shaft however.

If you have a local source for hex shaft (preferably 0.500 Inch) for compatibility with Vex/AM parts, it would be trivial to machine that down to .500 round or any metric size smaller that you want to use for bearings.

We have an on-line metals warehouse nearby, and simply pickup all our hex shaft there.

Comment- 6061 is fine for most shafting. We normally use 7075 as its it's yield strength is much better (73Ksi vs 40Ksi).