Step 1: Mark the position for the new lockset
Remove the old striker plate and install the new one that came with the lockset. If the shape or size is different, mark the profile and enlarge the opening with a chisel. Use the striker plate as a guide for the placement of the lockset. Using a spirit level, mark the line of the openings in the striker plate on the front of the door. Transfer the markings to the edge of the door to position the lockset tool.
Use a spirit level to mark where the top and bottom of the opening in the striker plate line up on the new door.
Step 2: Use a lockset installation guide to position the lockset holes
The lockset installation guide can be adjusted to fit the backset of the lockset you are installing. The backset distance is usually listed on the package. Position the locket installation tool on the edge of the door and match it to your markings and measurements. Using the screws that came with your lockset, attach it to the edge of the door so it can serve as a guide for cutting the holes for the lockset and latch.
Attach the lockset installation guide to the edge of the door following the markings for the striker opening and backset distance.
Step 3: Drill the holes for the new lockset
Follow the directions that come wtih your lockset kit and bore a hole through the opening in the lockset installation guide. Drill just until the drill tip is visible on the other face of the door. Use the pilot hole as a guide and bore through the other side of the door until you have completely cut through the door. This method will prevent you from splintering the wood as you bore the opening. Use a one-inch bore to drill the opening for the striker by drilling through the guide on the edge and into the hole for the handle.
Use the lockset installation guide to bore the holes for the new lockset.
Step 4: Cut the mortise for the bolt plate
Take off the lockset installation tool and insert the mortise template that came with the lockset. Follow the guide and use a router bit to cut the outline for the mortise. Remove the template and use a chisel to remove the wood between the lines. Check the bolt plate often to be sure you do not chisel away too much wood. The depth is right when the plate sits flush with the edge of the door.
Use a router bit and the template that came with the lockset to cut an outline for the bolt plate mortise.
Step 5: Install the bolt
Follow the instructions that came with your lockset and install the bolt. Screw the bolt plate in place and make sure that it sits flush with the edge of the door.
Attach the bolt and bolt plate to the door.
Step 6: Attach lockset assembly
Attach the lockset assembly using the screws that came with it. Close the door and check the clearance to be sure it works smoothly and does not grate against the striker plate.
Attach the lockset assembly and screw it in place.