mortise lock | door lockset

mortise lock 

mortiselockA mortise lock should be fitted to an external door to make it more secure. If the lock is to be fitted on an existing door, there is no need to remove the door from its hinges. Should the door be new, however, fit the lock before hanging it. The striking plate, which receives the lock bolt, cannot be fitted to the frame until the door has been hung. In a paneled door the lock is fitted at the level of the lock rail; in a flush door it goes into the lock block, which is usually higher than a lock rail. Determine the position of the lock, and hold the casing on the front edge of the door. Mark the top and bottom lines of the mortise lock to be cut for the lock. Push a pencil through the keyhole of the lock, to mark on the face of the door where the keyhole of the door has to be cut. Using a tri-square, draw a pencil line on the stile edge, at right angles to the edge of the door, to mark the top and bottom of the mortise. To ensure that the mortise lock will be positioned centrally, measure the thickness of the door, and subtract from this the thickness of the lock. Set a marking gauge to half the remaining thickness, and use it to mark lines from both the inside and outside faces of the door to complete the outline of the mortise.

The easiest way to cut out the mortise for the lockset replacement is to bore a series of holes with a brace and bit, the diameter of which equals the thickness of the lock. The depth of the holes should be the same as that of the lock casing. Make sure that the brace is held square to the work. Clean out the mortise with a chisel, and push the lock casing into it to test that it is a good lit. If the lit is bad, withdraw the casing and examine it. Scratches in its paintwork and paint marks on the inside of the mortise lock will show where the mortise needs to be eased off slightly. Push the casing into the mortise once again, and then draw a line on the door edge around the face plate.

Using a chisel, pare out a recess in the edge to take the face plate and the cover plate. When fitted, the cover plate must be flush with the stile edge. Since the closing edge of the door is usually slightly beveled off, to allow it to enter the frame more snugly, the recess for the cover plate will need to be a little deeper along that edge. Make the hole for the key; drill the top half, then complete the lower half with a pad saw. Neaten the keyhole by screwing an escutcheon plate (a small metal surround) on each side of the door. A small pivoted cover may be incorporated on both plates, or merely on the one intended for inside. Now fit the striking plate to the door frame. To do this, close the door and turn the mortise lock with the key. A slight force on the key will cause the position of the bolt to be imprinted on the door frame. If the mark is not clear, try pushing a sheet of carbon paper between door and frame, or smearing a little paint on the end of the lock bolt.

Hold the striking plate on the frame, position its hole directly over the mark of the bolt, then draw on the frame the position of this hole and of the entire plate. Chisel out a mortise lock to take the bolt and a recess for the plate. Screw the plate into position Test that the lock works properly. If the bolt does not enter the hole in the striking plate easily, you might be able to enlarge the hole slightly with a metal file. Otherwise, the plate may have to be repositioned. Marks on the sides, top or bottom of the bolt and hole will show where the bolt is binding.