[Cothron Theiss]

I'm a big fan of the adapters you mentioned, but I didn't think a similar adapter could be made from 3/8" hex due to the walls becoming too thin, but if you've worked with them and they work, that's great. Do you use the aluminum hex shaft from Vex, or do you have steel shaft for this purpose?

Also, I'm not quite sure I understand what you mean with the thrust load. Do you mean the force pushing up directly against the CIM shaft?
If so, I was planning to use 1 or 2 thrust bearings from McMaster Carr on either side of the plate that the 3/8" shaft would pass through; one bearing between the driving bevel gear and the wheel carriage and one bearing between wheel carriage plate and the base mounting plate.
That's the current plan, but I really haven't gotten far enough to worry about it.