One of the most diffiult parts of this project is figuring out how to mount and drive the wheels.

I eventually decided to buy four relatively large (by robot standards) wheels, which were designed for a 12mm axle.  The motors I intend to use have a 6mm shaft.

 

I bought some 12 mm aluminium round bar and a 6mm to 12mm shaft coupler. I had to file a little off of the aluminium bar to insert it into the coupler, but it fit fairly easily. I was then going to glue the aluminium bar into the wheel hub, but I had second thoughts since I wasn't sure if the glue would hold. So, I decided to get some 3mm bolts and drill through the hub and the aluminium shaft, then insert a bolt through to hold it in place. It took a few tries to get the bolt to line up with the holes, but it fits like a glove now, it should work well.

 

I now need to make three more wheel mountings in the same way for the other wheels. Only the front two wheels will need shaft couplers, sine the rear wheels are not driven, they will be mounted into 12mm pillow blocks.

 

I will post more on the motors and mountings when I get to that stage.