[techtiger1]

My team 1251 has always used 5/8 in steel for our drive axles and usually miller bearings and or a plastic material with a high oil content called UHMW for bearings. Generally for transmissions miller bearings and not the plastic. We have never had a problem with the 5/8in shaft. We are currently working on a gearbox for our arm from the past years bot which uses 3/8 steel internal shafts and a 1/2 in output.I know the gears will have a set screw and a key way however I am not sure of the size as of yet.