pic: 114 Coaxial Final CAD
 

Re: pic: 114 Coaxial Final CAD
 

Looks good, but... it looks kind of weak at the top. If you get hit by say BOB with there 6 cim drivetrain, those two plates are going to bend and cause major headaches. It looks really nice though.

Re: pic: 114 Coaxial Final CAD
 

As for structure at the top, the main shaft is 1" diameter, running through two large mushing supported by two 1/4 inch plates. I'm not sure exactly how strong that will be (all my attempts at stress tests failed horribly), but it seems strong enough.

As for getting hit by a large robot, I think the wheel tread will slip before we get bent from other bot contact.

Re: pic: 114 Coaxial Final CAD
 

Here, you could intergrate this circular plate I have on my crab drive. Then you just add a few teflon pieces with groves for it to ride in.