1 Cutting the keyhole
To mark the keyhole location on the door, measure the distance between the outside edge of the lock and the center of the key chamber on the inside of the lock. (The lock being installed here is illustrated on page 63.) Then transfer your measurement to the door, measuring from the rabbet cheek on the door’s back face. You need to drill two holes for the key: one for the shaft and a narrower one for the key bit, which is the strip of metal below the forward end of the shaft. Bore the wider hole first, using an electric drill fitted with a twist bit slightly larger than the key shaft. Then fit the drill with a bit slightly larger than the thickness of the key bit and bore a second hole below the shaft hole (right)-, locate the hole to suit the key. Hold the door steady as you drill the holes. Use a small file or a riffler to join the two holes and create a cavity through which the key fits easily.
Mounting the lock and making the bolt mortise
Position the lock on the back of the door, sliding the key chamber in the hole in the door, and fit the key into the lock. With the key in place, hold the lock steady while fastening it to the door (left). Make sure that the lock is square to the edge of the door as you drive the screws. To locate the mortise for the bolt, turn the key to extend the bolt and use a pencil to coat the end of the bolt with graphite. Retract the bolt and close the door. Extend the bolt against the edge of the mullion to mark its location and use the drill and a chisel to cut a mortise centered on the pencil mark. If desired, install an escutcheon around the keyhole.