Re-keying a lock means altering the locking mechanism so that the original key will no longer work with the lock. A new key will need to be made to operate the lock after it is re-keyed. Re-keying a lock is a common occurrence and part of the standard repertoire of skills for a locksmith. For example, when someone buys a house, car, or boat that has been previously owned, the buyer may want the locks re-keyed so that the previous owner’s keys will no longer operate the locks. The owner may also need a lock re-keyed if the key is lost. Re-keying a lock is generally easier and less expensive than installing an entirely new lock. Also, the owner may consider the existing lock to be visually appealing and not want to change it. Below is some useful information brought to you by our friends over at tacomalocksmith.org.
Re-keying the most common types of lock consists of six basic steps:
1. Remove the lock plug
2. Remove each disk or pin from the plug
3. Change the order of the disks or pins and replace them in the plug
4. Cut a key to match the new arrangement of disks or pins.
5. Reinsert the plug into the shell.
6. Test the new key to make sure it works.
Two common types of locks are disk tumbler locks and pin tumbler locks. The methods of re-keying them are similar.
Re-keying a disk tumbler lock
A disk tumbler lock holds the plug in place using disks that fit into slots in the shell of the lock. When the correct key is inserted into the lock, the disks are moved away from the slots in the shell, allowing the plug to turn. The disks within the lock contain slots that are located in different places on the disks, so that a key with different cuts along its blade is needed to open the lock. Re-keying a disk tumbler lock involves reordering the disks so that a different key is needed.
First, the plug must be removed from the shell. Usually a retaining clip holds the plug in place, and a small hole must be drilled in the lock to remove the clip. After re-keying, the hole can be filled with a material such as epoxy, and then sanded and polished.
The plug is removed and placed in a vise and can be cleaned with a spray solvent. The disks are then removed and reinserted in the lock in a different order. At least two of the five disks in the lock must be switched to properly re-key the lock. Of course, the swapped disks must have their slots in different positions, otherwise swapping them would have no re-keying effect.
Once the disks are swapped and the plug reinserted in the lock, the last step is to cut a new key. One way is to code cut the key, which is easy since the positions of the disks are known. Another way is to hand cut the new key, using the original key as a guide.
Re-keying pin tumbler locks
Pin tumbler locks use pairs of metal pins to keep the plug from turning. Each pair consists of an upper pin which is in the shell and a lower pin which is in the plug. The lower pins are of varying lengths. When the correct key is inserted in the lock, the lower pins are raised to the correct heights to allow the plug to turn, releasing the locking mechanism. Re-keying a pin tumbler lock involves gaining access to the lower pins and switching their positions in the lock.
The most common type of pin tumbler lock has a retainer plate covering the plug. Two machine screws are removed to expose the plug. The key is inserted in the plug and the plug is removed. A plug follower, which is a specially designed tool, is inserted behind it to keep the upper pins from falling out.
With the plug removed, the lower pins can be replaced to re-key the lock. After the pins are swapped or replaced, a new key is cut. Cuts are made on a blank key to raise each lower pin until it is at or just above the correct height. When a pin is just above the right height, it is sometimes easier to file the pin down rather than making a finer cut on the key. When the new key is completed, the plug is then reinserted in the shell and the retainer plate replaced.
There are many do-it-yourself re-keying kits available on the market to enable homeowners to re-key their own locks. A common version of these kits comes with a new set of lower pins, a new key, appropriate tools such as a plug follower, and an instruction manual. The plug is removed, the new lower pins are inserted in the correct order, and the plug is replaced. The lock is now re-keyed with the new key provided. Each major key manufacturer provides their own re-keying kits, and they are generally not interchangeable between brands.