pic: 4 inch Wheel Render

[artdutra04]

Originally Posted by NickE

If you have a hex broach and an arbor press, it will be much cheaper than $15/wheel to get the hexagonal hole.

A 1/2" hex broach is only like $200 on McMaster, so if you plan on making more than 13 hex broached parts, its probably worth it. (A 6wd live axle would require 16: 6 wheels, 10 sprockets.)

If you're tight on money and like working with your hands, you can make your own hex broach for 'soft' materials like plastic or aluminum. All you need is an old HSS end mill, a lathe, and a precision grinder. It'll work good enough for FRC-style applications.