When, Why, and How to Rekey Locks
Updated: Aug 23, 2019
The main purpose of rekeying is to re-establish key control. Who has keys to your home or business? Basically, any time there is a change of ownership or possession of a property, the locks should be rekeyed. Otherwise; previous residents, their family, their friends, their neighbors, and who knows who else may well have the keys to your property. There is no security with that possibility. This is as true when you are renting a property as when you own. Typically, a good landlord will have the property rekeyed when a new occupant moves in. Unfortunately, some landlords show little or no concern for their tenants' safety and security and leave it to the tenants to take care of for themselves. These landlords should be aware of the liability they may incur if a former resident returns and is able to readily enter property they are no longer authorized to be in. It is a risk for the new tenant that should not ever exist. The landlord is similarly at risk if a former tenant is able to access the property while it is unoccupied.
Many smart landlords, with multiple properties, will not only have the locks rekeyed, but set up on a master key system. This allows the landlord to have necessary access to their property while each tenant has their own individual key. This is especially the case for multi-unit buildings where the fire department requires access to the master key for use in emergencies. This is the case in many strip malls and office complexes. The difficulty in this case is that all locks need to be rekeyed by the locksmith that set up the system in order to maintain its integrity.
There are other occasions were rekeying is warranted. If a key is lost, stolen, or misplaced; it is prudent to rekey the locks. Basically, any time you cannot account for all keys to your property, it is a matter of safety and security that calls for rekeying the locks. An advantage to rekeying locks on a regular basis is that it allows for a locksmith to check on the overall condition of the locks. Are the locks working correctly? Are the strikes properly aligned? Is there any other problem with the door or locks? Also, over time, keys wear and may not operate the locks as well as they should, so rekeying can properly be considered preventative maintenance.
Before getting into how a lock is rekeyed, it should be mentioned that there are some exceptions. In residential applications, there are some locks designed to allow the homeowner to rekey their own locks without calling a locksmith. The main two locks of this type are the Kwikset Smartkey and Schlage SecureKey locks. The Schlage SecureKey is no longer made, but you may have them on your home. They require a special keys cut the same as the as the old and the new keys. The special "blue" keys used to rekey the Schlage SecureKey locks are getting harder to find and, as mentioned, they needed to be cut the same as the other keys. The Kwikset Smartkey locks require a special tool as well as precut keys. Neither used pins as in other standard lock cylinders.
The Kwikset Smartkey locks can be identified by the small slot just to the left of where the key is inserted. The Schage SecureKey locks could be identified by a small plus sign (+) just above where the key is inserted.
Rekeying other standard locks, including standard Kwikset and Schlage locks, is a matter of removing the cylinder from the lock, disassembling it, and replacing the springs and pins inside the cylinder so that a new key will operate the lock. The old key will no longer work.
The photo above shows some of the usual tools usually necessary to rekey a standard lock cylinder, including the pin kit and several specialty tools used to disassemble various manufacturers' locks. The pin kit shown is called a universal kit because the pins in it will work with most standard and residential locks. It is a .003 kit which means that the difference in pin lengths in the kit is only three thousandths of an inch. This allows great precision in rekeying a lock, which is necessary because it only takes a few thousandths of an inch to make the difference between a working lock and one that works roughly or not at all.
This particular cylinder uses a screw-on cap that has a spring-loaded pin retainer to attach the tailpiece to the cylinder. The pictured tailpiece is used with many deadbolts.
In the above photo, the spring and pin that retain the cap have been removed. The round disk is an additional feature that keeps anyone from trying to manipulate the lock by inserting anything through the keyway.
When, as in this case, no key exists for the lock, it is common to use an uncut key blank and a metal shim to separate the top and bottom pins within the lock.
A follower is used to push the core and bottom pins out of the cylinder. Without the follower the top (driver) pins and springs would have fallen out of the cylinder as well. Since this is a new cylinder, those parts weren't changed. In many cases, these parts are changed, using pin tweezers and the follower to place the proper springs and top (driver) pins into the top of the cylinder body, also known as the bible.
The appropriate pins are added to the core so that, when the key is inserted, the bottom pins are level with the top of the core, also known as the shear line. With the key inserted, the bottom pins come just up to the shear line and the driver pins are pushed beyond the shear line, into the bible. This allows the core to turn within the cylinder. This core was pinned to a 5-pin key. You can see that there is an empty pin chamber. If pins were placed in the sixth chamber, a 6-pin key would be required, but the process is the same.
The repinned cylinder after the tailpiece has been replaced. the key is turned in the lock. At this point the cylinder can be replaced in the lock. Only a key cut the same as the new key will work. No other keys will work. If a lock is masterkeyed, additional master pins would have been installed between the bottom pins and the drivers, effectively creating additional shear lines. Each master pin doubles the number of keys that could operate the lock.