Draw a tape measure from the latch edge of the door to the center of the doorknob or deadbolt lockset. Most contemporary locksets are either 2-3/8 inch (6cm) or 2-3/4 inch (6. 5cm) diameter. The bolt or latch in many new locksets are adjustable for both, but make sure before leaving your hardware store to keep from having to backtrack. Older locksets may vary in size, but are generally smaller, requiring more extensive carpentry (and greater woodworking skills). If that’s what you have, try checking vintage renovation stores for a “new” lockset. Tip: Determine which brand of lock you have. This is usually printed on the latch, but can also be found on the key — useful if the plate has been painted over, or is a leftover from an old doorknob set. You won’t need an exact replacement of your old lock, but knowing the brand, style, setback, and features of the old lock will help ensure that your new lock looks, fits, and works as advertised. [1] X Research source
Don’t let the door close or you will either have to re-insert the half of the knob with the “blade” on it or use a screwdriver or butter knife to unlatch it.
If your new lock is the same brand and model as the old one you may be able to keep your existing latch plate and strike plate. Hold the new plates up to the old and compare — if they’re the same, it is better to leave the old ones in place if possible. Removing and replacing screws tends to weaken their hold in the door. If you can’t get the new screws to bite, you may have to shove a small splinter of wood (or two) into the screw hole and snap them off flush with the edge of the door (toothpicks work well for this). Another alternative is to purchase longer screws, but make sure that the screw heads are identical to the ones provided by the manufacturer or they may not seat properly and cause problems.
If the new latch has trouble staying put in its recess, fit the screws into the latch and then tighten down.
Make sure that the strike plate lines up with the new lock. If it doesn’t, it’s advisable to replace the strike plate.
If your deadbolt lock has decorative caps over the screws, use a punch and hammer to knock the caps off center and then grab them with pliers. Then use the Allen wrench to unscrew the mountings. You can also twist off these decorative caps using your finger. If they still won’t budge, drill them out instead.
From the outside, drill into the cylinder in the middle of the deadbolt lock where the tumblers are found. Remove the tumblers. [7] X Research source Alternately, drill on both sides of the deadbolt, halfway between the top and bottom. Drill through on both sides until the exterior covering comes out. Insert a screwdriver into the latch and turn the knob lock.
Once you’ve installed the deadbolt on the side of the door, use a screwdriver to test the functionality of the deadbolt.
