Rekeying a lock changes the small pin-style parts inside the cylinder that read the key, so a newly cut key turns the lock and the old key no longer does. The lock stays on the door and stays the same lock: same body, same bolt or latch, same handle and finish. Only the key code changes, meaning the pattern of cuts the cylinder will accept.
The key code and the lock are two different things
A lock has two layers worth separating. The lock itself is the hardware: the deadbolt or knob, the bolt or latch that reaches into the frame, the trim and the screws. The key code is the pattern of cuts the cylinder will accept. Rekeying changes the key code and leaves the hardware where it is.
What the cylinder does inside the lock
The cylinder is the part with the keyhole, and its only job is to read the key. In a common pin tumbler cylinder, a rotating core called the plug sits inside a fixed outer housing. A row of small spring-loaded pin stacks bridges the two. While those pins straddle the gap, the plug cannot turn.
Each pin stack has a key pin, which rests on the key, and a driver pin above it. The right key lifts every key pin to the height where its top meets the seam between plug and housing. That seam is called the shear line. With all the stacks split at the shear line, the plug rotates.
Turning the plug moves a cam or tailpiece at the back of the cylinder, and that part throws the bolt or pulls back the latch. The bolt, the latch, the strike plate on the frame, and the rest of the door hardware do the securing. The cylinder only decides whether the key in your hand gets to move them.
Rekeying swaps the key pins, and sometimes the driver pins, for lengths that match a different key. The plug, the housing, and everything behind the cylinder stay put.
Copying, rekeying, and replacing are three different jobs
Two mix-ups are common. One is that rekeying means installing a new lock. The other is that it only means cutting a different key. Neither holds, and the old key shows the difference.
- Copying a key: a new key is cut to match the key you already have. The cylinder is untouched, so the original key and every earlier copy still work.
- Rekeying: the pins inside the cylinder are changed to fit a new key pattern. The lock stays installed, and keys cut to the old pattern stop turning it.
- Replacing: the lock comes off the door and different hardware goes on. The look, the style, and the type of lock can change along with the key.
A different key cannot simply be cut for an unchanged lock, because the pins inside decide which key turns. Changing who can open a lock means changing its pins.
What stays exactly the same after a rekey
Since the work happens inside the cylinder, the parts you see and use every day carry over.
- The lock body and the cylinder housing
- The finish and color
- The knob, lever, or deadbolt style
- The holes and cutouts in the door and frame, known as the door preparation
- The bolt or latch and the strike plate it meets
- How the lock operates, including which way the key turns and how the inside thumb turn works
The door looks and works as it did before. The difference is the key on your ring.
Old keys, new keys, and where a rekey stops
After a rekey, only the new keys operate the rekeyed cylinders. Old keys, including forgotten spares and copies handed out long ago, still slide into the keyway, the shaped slot the key enters, but they will not turn. Any future copies get cut from one of the new keys.
A rekeyed lock is physically the same lock, so its resistance to picking or force does not change in either direction. What changes is who holds a working key. Rekeying does not make an ordinary lock a high-security one. That takes hardware built with features a standard cylinder lacks.
Rekeying also leaves wear and damage where they are. A bolt that drags or a loose handle behaves the same afterward, because a rekey changes only the pins. Those are repair or replacement questions.
To talk through your own locks, call Williamsburg Locksmith and Key Copy at (347) 699-9268.
Frequently asked questions
Can several locks be rekeyed so one key works for all of them?
Several locks can often be rekeyed to share one key, which is called keying alike. The main condition is that the locks use the same keyway, the shape of the slot the key slides into, because one key blank has to fit every lock. Locks from different makers or product lines often have different keyways, and those generally cannot share a key without changing a cylinder.
Does rekeying work on every kind of lock?
Rekeying does not work on every lock. Standard pin tumbler cylinders on many deadbolts and knobs are built to be rekeyed. Some locks are sealed or not designed to be opened, some cylinders are too worn to be worth it, and some high-security designs restrict who can get matching parts and key blanks. Whether a given lock can be rekeyed depends on its cylinder design and condition.
If a lock is worn or sticking, will rekeying fix that?
Rekeying does not fix a stiff or sticking lock, because a rekey only changes which key pattern the cylinder accepts. Stiffness usually comes from somewhere else: dirt or wear in the plug and housing, a bolt dragging against a misaligned strike plate, or a door that has shifted in its frame. One useful observation: if the key turns freely with the door open but binds with it closed, the trouble is likely alignment rather than the cylinder.
Can a smart lock or keypad be rekeyed?
A smart lock or keypad can only be rekeyed if it has a mechanical key cylinder, and many include one as a backup way in. That backup cylinder may be rekeyable like any other, depending on its design. The electronic side is separate: codes and app access are changed through the lock's own settings. Changing codes does nothing to the backup key, and rekeying does nothing to the codes.