Originally Posted by
mconlonx
Actually, I think it would be harder to cut splines into a hub than threads. Cutting threads on the end of a hub is a simple machine operation. Cutting splines with a square bottom (the flat part which would be closest to the flange), not so easy. It would probably have to be a piece manufactured separate from the hub and attached, or the hub could be directly splined but without flanges which would then have to be pressed on or otherwise attached. More steps/pieces, higher cost; higher cost, less buyers...
It's all done on CNC lathe. Threading/cut outs/whatever. CNC's are super fast and cost affective (with the exception of how expensive the machines are) The cycle time per part would actually be slightly faster to notch the splines than to cut the threads.
And yes...I am a machinist.