How to Mill a Pocket on the Vertical Milling Machine

[stevec]

I'd drill the 4 corners with a bit large enough to eat up the radius of the D-I square then drill just shy of the square and finish the sides with an end mill. A little 3/4 hole at each corner isn't gonna affect the torquing of the studs with the key. As a matter of fact it's like a "flank drive"