Buy a rekeying kit
Have you ever lost your house keys and been worried that a stranger could get in? Unless you're the first occupant of the property, you never can be sure how many copies of your keys exist. Locksmiths typically charge a fee to re-key an individual lock, even when you bring it to their shop. Since most homes have multiple doors with multiple locks, rekeying can get expensive.
You can re-key a lock like a pro and at a fraction of the cost. Re-keying kits are available for most lock brands, but they're not interchangeable. You have to buy a kit for each brand of lock used in your home. (If you're lucky, they'll all be the same brand!) They're available in home centers and hardware stores and through online suppliers.
Each kit will rekey six locks, but you can order extra pins if you need to do more. The kit will work on entrance and deadbolt locks, and it comes with two keys and all the tools you'll need, except a screwdriver. But keep your current keys—you'll need them to remove the cylinder.
We used a Schlage brand lock for this story, so if you have a different brand, be sure to check the instruction sheet for minor variations.
Remove the knob
Insert the key in the lock and turn it until the door is unlocked. Remove the doorknob and lock cylinder housing as shown in Photos 1 and 2.
Remove the retainer ring
Use the special retainer ring tool supplied with the kit to force off the thin retainer ring (Photo 3). Set the ring aside so you can replace it later.
Remove the cylinder plug
Photo 4: Remove the cylinder plug from the cylinder
Insert the old key and turn it either to the left or right. Remove the plug by pushing the plug follower (supplied in the kit) through the cylinder. Make sure to keep constant pressure between the plug and follower so the pins and springs don't pop out.
The most critical part of this operation comes next. Photo 4 shows the cylinder plug being removed from the cylinder. The top of the cylinder contains pins and springs, which keep pressure on the keyed pins. You must keep the plug follower tight to the cylinder plug until it's completely removed so that the pins and springs don't pop out of the cylinder. If they do fall out, it's not the end of the world—just make sure you pick them all up and refer to the enclosed instruction sheet for reinserting them.
Insert the pins and reassemble the lock
Photo 5 shows how the new pins are inserted into the cylinder. Once the new pins are in, reverse the steps to reassemble the lock.