What Actually Happens When You Rekey a Lock
If you've ever wondered what a locksmith does when they rekey your lock, here's the step-by-step process. Understanding it helps you appreciate why it's a skilled job — and why DIY rekeying on most locks is impractical without specialized tools.
Tools Required
- Pin kit — A set of brass pins in graduated sizes (typically sizes 0-9)
- Follower — A cylindrical tool for removing the cylinder plug without losing the springs and driver pins
- Pin tweezers — For handling tiny pins
- Key cutting machine — To cut a new key to the desired bitting
- Screwdriver — To remove the lock from the door
- Shims — Thin metal strips for holding pins in place
The Process (Step by Step)
Step 1: Remove the Lock from the Door
The locksmith removes the lock's interior thumb-turn (or knob), then unscrews and removes the cylinder. On a deadbolt, this typically involves removing two screws on the inside face. On a knob lock, a retaining tool is used to release the cylinder.
Step 2: Remove the Cylinder Plug
This is the critical step. The cylinder has two parts: the shell (outer body) and the plug (the rotating part where the key goes). The plug contains the key pins (bottom pins) and is held in place by the driver pins (top pins) and springs.
The locksmith inserts the current key (which aligns all pins at the shear line), then uses the follower to push the plug out of the cylinder shell. The follower keeps the driver pins and springs in place in the shell. If this step is done wrong, all the springs and driver pins fly out — and the locksmith has to reassemble from scratch.
Step 3: Remove the Old Key Pins
With the plug removed and the old key still inserted, the locksmith removes the key pins (bottom pins) from each of the 5-6 pin chambers. The driver pins and springs remain in the shell, held by the follower.
Step 4: Cut a New Key
The locksmith cuts a new key to the desired bitting (the pattern of bumps and valleys). This can be a random pattern or a pattern that matches other locks (for keying alike). The key is cut on a key-cutting machine that mills the profile into a blank key.
Step 5: Insert the New Key and New Pins
The locksmith inserts the new key into the plug. Now, each pin chamber needs a key pin of the correct height so that the pin sits flush at the shear line when the new key is inserted. The locksmith selects pins from the pin kit based on the new key's bitting and drops them into each chamber.
For a master key system, master pins are also inserted — these create a second shear line that allows the master key to also open the lock.
Step 6: Reassemble the Cylinder
The locksmith slides the plug back into the shell, using the follower to push the driver pins and springs into their chambers while the plug takes their place. This is a delicate operation — the pins must align perfectly at the shear line as the plug slides in.
Step 7: Test the Lock
Before reinstalling the lock, the locksmith tests:
- The new key turns the lock smoothly
- The old key does NOT turn the lock
- The lock opens and closes without binding
- If keyed alike, the shared key works in all rekeyed locks
Step 8: Reinstall the Lock
The cylinder goes back into the lock body, the lock goes back on the door, and the screws are tightened. The locksmith tests the lock in the door to confirm everything works smoothly.
Step 9: Provide New Keys
The locksmith provides copies of the new key. If you had multiple locks rekeyed to the same key, you get one key that opens all of them.
How Long Does It Take?
- Single lock: 10-15 minutes (experienced locksmith)
- 3 locks, keyed alike: 30-45 minutes
- 5+ locks, master key system: 1-2 hours (design + rekey)
DIY Rekeying: Only for SmartKey
The only locks designed for homeowner rekeying are Kwikset SmartKey locks. The process:
- Insert the current working key
- Insert the SmartKey tool into the small slot next to the keyway
- Remove the old key
- Insert the new key
- Turn the new key 90 degrees and back
- Remove the SmartKey tool
Takes about 30 seconds per lock. No disassembly required. The SmartKey mechanism uses a sliding sidebar instead of traditional pins, which allows for tool-free rekeying.
However: SmartKey locks have lower security ratings than traditional pin tumbler locks and are more vulnerable to certain attack methods. If security is a priority, stick with traditional locks and have a locksmith rekey them.
FAQ
How long does it take to rekey a lock?
A professional locksmith can rekey a single lock in 10-15 minutes. For 3 locks keyed alike, expect 30-45 minutes. A master key system for 5+ locks takes 1-2 hours including design.
Can I watch the locksmith rekey my lock?
Absolutely. Most locksmiths are happy to explain the process as they work. Watching helps you understand what you're paying for and confirms the job is done properly.
Why can't I rekey my own lock without special tools?
Rekeying requires a pin kit (dozens of tiny pins in graduated sizes), a follower tool to remove the cylinder plug, and a key-cutting machine for the new key. Without these tools, the internal pins can't be changed. Kwikset SmartKey locks are the exception — they're designed for tool-free homeowner rekeying.
What happens to the old keys after rekeying?
The old keys simply stop working. The lock's internal pins are rearranged to match the new key's pattern, so the old key's pattern no longer aligns the pins. You can keep or discard the old keys — they're now just pieces of metal.
Need rekeying services service right now? Call (855) 373-1159 and our 24/7 dispatch center will connect you with a licensed professional near you.