The following is excerpted from “The Essential Woodworker,” by Robert Wearing.
The straight cupboard lock is screwed directly onto the inside of the door with no preparation, hence no description of the method is required. For quality work something better is required. This is the brass cut lock (Fig 447): ‘cut’ meaning cut into the door. The cut drawer lock is similar except that the keyhole is at right angles to that of the cupboard lock. In buying a cupboard lock specify whether it is to go into the right- or left-hand stile.
Prepare for marking by setting a marking gauge to the distance of the key pin (Fig 448). Mark the chosen position for the keyhole with a square on the face of the door then carry it round onto the edge. The gauge marks the distance from the edge (Fig 449). At this stage drill a very small pilot hole for the pin. Offer up the lock to the centre line and mark the length of the box on the door edge (Fig 450).
This is an essential method because on some locks the pin is by no means in the middle of the lock. Mark out this primary cavity with a square and gauge. Weaken the wood with a number of diagonal sawcuts. Waste can then be removed by chisel. Use the simple hand router to complete the process to depth (Fig 451).
Hold the lock in place and scribe round it. Remove the waste to produce the second cavity (Fig 452). The keyhole can now be shaped using a larger drill and a coping saw. It may be finished with a round and a thin warding file. The keyhold is often left like this, but to prevent wear as the key is inserted an escutcheon may be fitted. The brass insert (Fig 453) requires the opening to be carefully filed out until the escutcheon can be pressed in with a G-cramp. Alternatively an escutcheon plate can be made from ebony, rosewood, bone, ivory, etc, and let into the door, either flush or slightly proud. A great variety of shapes is possible (e.g. Fig 454).
For fitting a drawer or till lock the routine is virtually the same. The socket for the bolt must be cut into the carcase. The door is closed with the bolt out, from which the length marking can be taken. Width markings can be made with a marking gauge (generally the points of a mortice gauge will not close sufficiently). Make due allowance for an inset or outset door. An alternative method favoured by some workers now is to ink the bolt end thoroughly with a thick felt marker and to quickly make a print with this before the ink dries, either onto the wood or onto a piece of masking tape. A brass plate can be recessed into the carcase to take the bolt. Unfortunately these are not usually for sale with the lock and must be individually hand made (Fig 455). (Making one by hand is an easy job – saw a piece of thin brass, file it to shape and drill holes in it for the screws.)