There are two answers.
If you want to run a shaft through the bearings, which are 3/8", just get an aluminum spacer. For example, if you want to run the wheels on 1/4" shafts, just get an aluminum rod with 3/8" OD and 1/4" ID. These are very common at OSH, in fact our robot uses a bunch of that metal for our manipulator. However, the ID is actually less than 1/4", so we just drill it out on a drill press. You have to be careful to keep concentricity, but it can easily be done. So yea, just drill that stuff out to whatever
ID you want.
If you are talking about taking the bearings off the skyway and powering it, like having a shooter wheel on a powered shaft, it can also easily be done. The bearings are .875 OD, so the hole in the wheel is .875 ish. However, there is a flange to keep the bearings from going in, which has an OD of a little less than .750". You can press a .750 shaft into it, which can have the proper bore drilled into it for your uses. This can't take too much torque, but its easy. If you want it to take more power, this is what my team did for our shooter wheel:
We drilled out the flange (making a through .875" hole in the wheel) and glued in a cylinder of aluminum with a .875" OD and .5" ID, which was keyed. Along with the glue, we used four steel rivets through the wheel and into the aluminum to transmit most of the torque. It is a very nice and easy way to do this, and you just need a drill press. (or if you're really skilled, a hand drill). I'm sure if you guys dont have a drill press, there would be some team willing to let you use theirs. Just make sure you have a .875" drill bit, and use a low cutting RPM
