Prop Shaft

[HotWater]

I don't like either one of those slots. Both have zero fillet radius. My opinion, they should have .040 minimum fillets. But between the two, I would take the shaft cut with the endmill(bottom) less work hardening with this process. I feel the slots on the prop shafts should be cut with a ball endmill and the key should have the same full radius shape.

Thank you for the response. I've never seen key stock radiused on one side to match a ball endmill slot. Is that common stock? Can you explain to me what fillet radius is and the benefit of it?