[maclaren]

I think that a dead axle is the only way to go. The reason being is that the torque is moved out from a tiny key to a bolt pattern on the side of the wheel which causes less wear and problems and allows you to remove a lot of weight.

The method of using a "pillow block" with no bearings is a good method and the industry name for these are shaft hangers. On our 2005 robot we used a 5/8" aluminum tube axle with shaft hangers that had a socket head cap screw holding the axle in the shaft hanger and keeping it from spinning. If you want to use a aluminum axle I would recommend using a Rulon or PEEK Flanged plain nearing pressed into your wheels. Rulon and PEEK are PTFE(teflon) composite berings that are specifically designed for soft shaft materials. Many other beraings are designed for hard or very hard shaft materials such as hardened steel axles and those are heavy.

A nother way to do mount a dead axle if you are using palt side panels on your drive train is to tap the end of you axle and machine a flat in to the end of the axle and and then machine a corresponding shape into the face of the side plate and then drill a hole for the screw through the side plate. But this requires a lot of machining

If you do it right there is virtually no torque on the axle and if you make sure to have little to no unsupported length in the axle then it will have no chance to deform or bend. We even used a 1/2" aluminum tube axle on the front caster wheels that we had on our 2006 robot.