For my college engineering design project my team is basically designing a mousetrap car that has to travel a minimum distance of 3 meters and the dimensions are 20cm X 10cm X 10cm. The car will rely on its coasting phase to travel the majority of this distance so the reduction of friction between the axle and body needs to be at a minimum. I was thinking of using ball bearings for high quality rc cars but the only problem I face is how to keep them in the body which is basically a sheet of aluminum with two 1 cm edges bent 90 degrees downward with an 8 cm hole drilled through each side for the axles (od of bearings is 8 cm). I was thinking of using epoxy to keep them in but id like to hear other opinions.
but it may overcomplicate it, unless you can use the complete wheels with the axle. .
if your axle shaft was solidly mounted to the vehicle, perhaps even a threaded bolt, and nothing touches both the inner and outer races, you could just tighten the nut on one end and it would stay together. i would suggest using a locknut, which can be left loose without loosening up from vibrations or the spinning wheels. i might suggest roller blade wheels and bearings. abec 9 bearings are very good low friction bearings, or the bones brand ceramic bearings are even better. with a large profile wheel, a wheel that covers more distance per revolution, a set of abec 9 bearings can allow a good roller blader to hit speeds of over 70 mph. and roller blade wheels are setup with their bearings to be through bolted fairly tightly in place, which might be ideal for your setup. another thing may be skateboard parts. the trucks, if tightened up real tight to prevent lean steering, might make very easy to use axles that are meant ot have wheels on them.....
