Although a chisel mortise is best known for its use in a joint known as mortise-and-tenon, it is a great way to countersink a hinge plate in a door. With the right tools and instructions, you can chisel a mortise in less than five minutes.
Draw the Mortise Outline
For a door with 3 hinges, you'll need to chisel 6 mortises: 3 on the door and 3 on the door jamb. Place each door hinge on the door edge that will fit against the door jamb when the door is closed. With a pencil draw a line on the door, following the edge of the hinge.
Cut a Slot
Hold your chisel edge on the pencil line, bevel side toward the door edge. Tap the chisel end with your hammer or mallet, cutting a slot to the depth that will equal the thickness of the hinge.
Chisel Out the Mortise
Hold your chisel flat against the surface of the mortise you wish to remove, bevel edge down. Then, tap with a hammer or mallet until you've removed the wood, leaving the surface of the mortise flat and even.