How to Convert a Mortise Lock to a Tubular Latch Door

Measure the distance from the edge of the door to the center of the doorknob with a measuring tape. Although this distance, sometimes referred to as “backset,” is typically 2 3/4 inches, the backset can vary.

Measure the thickness of the door with the measuring tape. Ensure the tubular lock you purchased accommodates the measured dimensions.

Remove the set screw from the base of the interior door knob with a screwdriver and pull the knob away from the door. Pull the square spindle and the exterior knob out from the other side of the door.

Remove the screws that secure the mortise lock to the door with a screwdriver. The screws are on the edge of the door.

Pull the mortise lock out of the edge of the door.

Mark the location of the tubular lock on the door. Use the template provided by the lock manufacturer as a guide. Tape the template to the door and press an awl or nail through the template and into the door, then remove the template.

Bore a hole through the door to accommodate the new lock with a drill fitted with a hole saw.

Remove material from the edge of the door to accommodate the new latch face plate, if necessary. Drive a chisel into the edge of the door at a sharp angle with a hammer to remove material. Remove small amounts of wood at a time to avoid removing too much.

Insert the new latch into the edge of the door and tighten the latches’ securing screws through the latch and into the door with a screwdriver.

Position the escutcheon plate included with the conversion kit against the door. Ensure that the hole in the center of the plate aligns with the door handle hole within the door. Mark the location of the plate’s screws on the door and remove the plate. Drill a small starter hole through the marks. Position the plate against the door and install the plate’s securing screws with a screwdriver.

Insert the exterior door handle through the lock and against the door with the serrated edge of the key slot at the top of the slot.

Hold the exterior handle stationary and position the interior handle against the door. Tighten the handle’s securing screws with the screwdriver.