Originally Posted by
toytech
From the links you provided I may already have it, the tool I have I was under the impression was for facing the top of the crown, I will take some measurements.
The same cutter is used to face the crown as mill the diameter.
Think of it as the opposite of a drill. Rather than go through a donut to make a hole, a crown mill (holo-mill) removes the donut and leaves the "hole".
When you drill all the cutting is done at the bottom, and the diameter of the resulting hole is constant regardless of depth. A holo-mill works the exact same (but opposite) way, all the cutting is at the forward edge, and as it advances it leaves a pin of uniform diameter regardless of length.