Once I figured out how to do the hex I decided to go big. So, I'm making hubs for the wheel with the hex and a flange that looks like a brake rotor. That pulls up against the inside spokes of the wheel with a 6-32 cap screw to keep it parallel with the wheel. Then I drill the inside of the hub to fit a 1/4" steel axel.
Hex milled on the mill using a slip fit nut attached to the round. Then moved to the lathe to turn the rest.
Turned down and parting it off here.
Jim