The wheels also have a slightly larger ID than the power wheels axle, so some bushings were made to correct that. Here is a pic of all the things that were fabbed this weekend:
These are some photos of an adapter plate bolted onto the wheel:
And here is the whole bot as it sits, the metal tee in the middle of the axle is where the tail (or nose) wheel assembly is going to go, the tee is 1/2", as is the pipe nipple. The pipe nipple has been reamed out to a nice ID, where a metal rod fits in nicely, the metal rod goes out, and has a dogleg bent into it, in order to make the end where the castor will mount (the castor's mounting plate is a little higher than the main axle) higher. I shall weld the end of the rod that the castor is to be mounted to to a metal plate with the same dimentions as the mounting plate on the castor, and holes drilled into it for the castor to mount on. The PVC fittings are for the rest of the frame, the +s to make the outer frame and the tees will go straight up for mounting a paintball gun, compass sensor, GPS antenna, etc. on. I still plan to use the stainless dishwasher cover as a baseplate to bolt on after the frame is made.