How does a mortise drill bit work? - AskingLot- mortise drill bit for wood splitting ,8/6/2020· The auger bit cuts a round hole and the chisel bit, driven into the wood by the action of the drill press or mortising machine, squares off the round hole. How do you sharpen a mortise bit? Use the 220 grit diamond coated abrasive cone to remove any deep nicks or burrs left behind after honing the out side of your chisels.What Is a Mortise Chisel?A chisel bit fitted in a drill can also be used to make the deep cut faster. Later a lighter weight chisel, such as a sash mortise chisel, may be used to fine tune the cut by hand. The most commonly used sizes of mortise chisels are the 1/4 inch (0.64 cm and 3/8 inch (0.95 cm) chisels.