Installing a door lock

MATERIALS: Lock template, security lock

TOOLS: Screwdrivers, drill and bits, hole saw

If you’re installing a new lock on your door, chances are it’s a security (or dead-bolt) lock. Entrance door and passage locks are usually already in place. If you do find yourself replacing an entrance or passage lock, it’s much like installing a dead bolt. Instead of putting in the key cylinders, however, you’ll put in the doorknobs. If you’re putting in a new door and lock, get a predrilled door—the hole for the knob and latch are already there. Just screw the lock in place.

When you head out to buy a dead bolt, you’ll have a few choices. The biggest is how you want to open the door. Single-cylinder locks can be opened front the inside with a thumb latch. Double-cylinder locks require a key from either side. In most applications, a single cylinder is fine. A key opens it from the outside; a twist of the thumb screw opens it from the inside. But if you have a door with a window, a double cylinder provides more security. Someone breaking the window will still need a key to get in. However, someone needing to get out— in the case of a fire, for example—will also need a key. Most people solve the problem by leaving the key in the inside cylinder; this helps in the event of fire but is useless in preventing break-ins.

All door locks have what is called a “setback”—the distance from the edge of the door to the center of the knob or cylinder. The two standard setbacks are 2 3/4 and 2 3/8 inches. If you’re drilling the holes yourself, a lock with either setback is fine, and neither has an advantage over the other. If the hole is predrilled, measure the setback and get a lock that matches. If you arrive at the store only to discover you forgot the measurements, good news. Both locks and dead bolts are available with an adjustable setback.

INSTALL THE LOCKSET FIRST - If hanging a door from scratch, install the lockset while the door is on the sawhorses. That way you won’t have a swinging door to contend with while you’re drilling holes.

1 MEASURE TO FIND THE LOCK LOCATION. Tape the cardboard template, supplied with the lockset, onto the door. Use a nail or awl to mark the center of the cylinder on the face and the latch bolt on the edge of the door.

2 BORE A HOLE FOR THE LOCK CYLINDER WITH A HOLE SAW AND DRILL. To avoid splintering the door, drill through one side until the drill bit just starts to come out the other side. Remove the hole saw and then complete the hole from the opposite side of the door.

3 USING A SPADE BIT, DRILL TO BORE THE LATCH BOLT HOLE from the edge of the door into the cylinder hole. Keep the drill perpendicular to the door edge while drilling.

4 THE PLATE ON THE BOLT MECHANISM NEEDS TO BE INSET SO THAT IT'S FLUSH WITH THE EDGE OF THE DOOR. Lay out the recess by putting the bolt in its hole. Line up the plate and screw it into the door. Trace around the plate with a utility knife. Remove the plate from the door.

5 CUT THE OUTLINE OF THE RECESS BY HOLDING A CHISEL WITH THE BEVEL SIDE FACING THE INSIDE OF THE RECESS. Tap the butt end lightly with a mallet or hammer until the cut is as deep as the plate is thick. To help gauge the depth, measure back from the cutting edge of the chisel by the thickness of the plate, and draw a line on the chisel.

6 TO HELP REMOVE THE WASTE, MAKE A SERIES OF PARALLEL DEPTH CUTS Vu inch apart across the recess while holding the chisel at a 45-degree angle. Drive the chisel with light mallet blows to the butt end of the chisel.

7 CUT OUT THE WASTE CHIPS by holding the chisel at a low angle with the bevel side toward the work surface. Striking the chisel with a mallet will drive the chisel too deep; push the chisel by hand to make the cut.

8 INSERT THE LATCH BOLTIN THE EDGE HOLE. Insert the lock tailpiece through the latch bolt mechanism, and test-fit the cylinders. If the tailpiece is too long, snap it at the indentations by bending it with one set of pliers while holding it with a second set.

9 PUT THE STRIKE PLATE IN PLACE AND TRACE AROUND THE HOLE. Mark the center. Drill the latch bolt hole with a spade bit. Install the strike plate using the retaining screws provided with the lockset. Trace around it with a knife, and cut a recess for it the same way you cut one for the bolt. Screw the plate in place.

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