Today I countersunk all four brake pedals and side plates for AN470-AD4 rivets. At first they came out a bit shallow, then I noticed that even though I had deburred the edges of the pedals, there was still a slight burr at the corner where the edge meets the face. Once I ran those corners across a scotchbrite wheel, the countersinks came out right on.
The setup for countersinking brake pedals and side plates.