Couple things I think, say for a 1/2 inch bit 14 degrees is kind of standard. I always thought the longer the cutting edge the angle changes. maybe I am wrong. Different size width bits say a 3/8 bit has a different angle then and cutter length makes a difference on the angle. Different manufacturers of dovetail machines have bits that are designed to be used for that particular jig and the length of the bit and size dictate the angles... I think. I suppose aesthetics play into it as well.
Corey |