Locks are simpler than you think.
Most people think locks are complicated, but once you understand the shear line, pin heights, and how keys interact with the lock, everything starts making sense.
In this guide, I’ll walk you step-by-step through how to rekey a lock, how the pins work, and how locksmiths change locks to work with new keys without replacing the hardware.
What Is Rekeying a Lock?
Rekeying a lock means changing the lock so the old key no longer works and a new key does.
Instead of replacing the entire lock, a locksmith changes the internal pins inside the cylinder to match a different key.
This is one of the most common locksmith services because it is faster and usually much cheaper than replacing all the hardware.
Most houses already have perfectly good locks installed. In many cases, they simply need to be rekeyed to a new key.
Watch the full rekey process step-by-step as the lock is disassembled, repinned to a new key, and tested at the shear line.
How a Lock Actually Works
Inside the lock are a series of pins that must line up perfectly for the cylinder to turn.
Each cut on the key lifts the pins to a specific height. The deeper the cut on the key, the taller the pin usually needs to be to create the correct alignment.
The most important part of the lock is called the shear line.
If the pins line up perfectly at the shear line, the lock turns smoothly. If the pins are too high or too low, the lock will not work correctly.
Once you understand the shear line, locks suddenly become much easier to understand.
The shear line is where the pins must align perfectly for the lock to turn.
The Basic Tools Needed to Rekey a Lock
You do not need a huge toolbox to begin learning how to rekey locks.
Most beginner rekey jobs can be done with a few basic locksmith tools.
Common starter tools include:
- Tweezers
- A plug follower
- A pinning kit
- A Kwikset cylinder removal tool
- A key decoder or depth chart
- Small screwdrivers and picks
As you learn more, you can expand into additional locksmith tools and automotive programming equipment.
Step-by-Step: How to Rekey a Kwikset Deadbolt
The first lock many locksmiths learn on is a Kwikset deadbolt because the design is simple, common, and beginner friendly.
The basic process includes:
- Remove the deadbolt from the door
- Remove the cylinder from the housing
- Slide the plug from the cylinder carefully
- Remove the old bottom pins
- Insert the new key
- Install the correct new pins to match the cuts of the new key
- Verify that all pins align perfectly at the shear line
- Reassemble the lock and test operation
If the shear line is perfect, the lock will turn smoothly with the new key.
Common Rekeying Problems
If a lock does not work after rekeying, the issue is usually related to the shear line or incorrect pin heights.
Common beginner mistakes include:
- Pins sitting too high
- Pins sitting too low
- Springs falling out during assembly
- Installing pins in the wrong chambers
- Forgetting to fully seat the plug
- Testing the lock without verifying smooth key operation first
Most rekeying problems become much easier to diagnose once you understand how the shear line works.
Why Most People Replace Locks When They Don’t Need To
Many homeowners replace perfectly good locks simply because they want a different key.
In most cases, the hardware itself is still completely usable and only needs to be rekeyed.
A locksmith can usually change the lock to a new key much faster and cheaper than replacing every lock on the property.
Understanding how rekeying works can save homeowners money while keeping the existing hardware already installed on the doors.
Locksmith Blueprint | Locks Made Simple
Locks Made Simple was created to make locksmithing easier to understand for beginners.
Most people think locks are complicated until they finally see how the pins, keys, and shear line actually work together.
This educational division of Locksmith Blueprint focuses on real-world locksmith explanations, printable guides, diagrams, walkthrough videos, and beginner-friendly training designed to simplify locksmithing step-by-step.
Learn How Locks Actually Work
The more you understand the shear line, pin heights, and how keys interact with locks, the simpler locksmithing becomes.
Locks are easier to understand than most people think.