And I believe they use rasps in 0.5mm increments if I remember correctly, so it'll take a dozen different rasps to get to the final size.
They also use a ball type rasp on a drill to make the socket spherical. Oh, and don't forget the oscillating type saw they use to cut the head of the femur off
I'm a med student and watched a dozen of these procedures last fall. Knee replacement surgery is pretty interesting too.