Half Mortise Locks
Door & Drawer Locks
Locate the center of the drawer front (or the appropriate position on the door if mounting a door lock). Using the lock as a template, mark its outline on the back and upper edge of the drawer front. Be aware that the key pin is usually offset to one side of the lock and it is the key pin that must be centered on the drawer. With a sharp knife, ruler and square go back over these lines.
Use a router or chisel to create the shallow mortise for the lock plate (I use a 1/4" high speed steel straight cutter in a small router, as long as the cutter is sharp a router is very easily controlled freehand at this depth of cut).
Mark the outline of the lock body and adjust the router to suit this deeper cut. This cut will be covered by the lock and need not be so precise as long as you are careful to leave sufficient material for the mounting screws.
Measure from the top and from one side of the lock plate to the center of the key pin and transfer these measurements to the drawer front. Drill a hole large enough to accommodate the key shaft and with a keyhole saw cut the desired keyhole shape. Alternatively you could push the lock into place and use the indent created by the key pin to mark for the drill. If you choose this method be careful not to chip out the front of the drawer as the drill comes through (tapered drills are recommended). The lock can now be fitted.
Set the lock in exactly the same manner as described above. With the lock fitted and the lid strike plate locked into place, lower the lid and press firmly down onto the strike. The strikes have two little projections on the upper surface and these will leave two matching marks in the lid.
Release the strike from the lock, set it accurately in the indentations and mark around with a sharp knife. Set your router to the thickness of the strike and create a mortise. You will need to drill two holes to accommodate the marking pins or simply file them off. Clean up the corners with a chisel and screw the strike into place. If interference is noticed a file can be used to remove a little material from the strike pins.