Woodruff Key Seat Cutters are designed to mill standard Woodruff keyways in steel and other metals. They are the correct dimensions for Woodruff keys and are made oversize to allow for resharpening.
key seat cross section
Key Seat Style Notch Cut
Woodruff Key Seat (Shank) Cutters - Staggered Teeth page 282
Staggered teeth design cutter reduces chatter, has more chip clearance, and removes more metal at higher speeds and feeds than straight teeth cutters.
Woodruff Key Seat (Shank) Cutters - Straight Teeth page 283