Why Keys Snap Inside Locks — and What It Means for Your Lock
Keys break inside locks for several reasons. Metal fatigue is the most common culprit — a key that has been bent slightly during use, or that has a small crack near the bow, will eventually snap under the torque needed to turn the barrel. Cold weather makes the metal more brittle, which is why calls for broken key extraction spike on frosty mornings in Bermondsey. Keys can also snap if the lock itself is stiff or partially seized, forcing you to apply more pressure than the key can take. Worn-down teeth that no longer sit cleanly in the cam can cause the same problem.
The position in which the key breaks matters enormously. If a good length of the broken stub protrudes from the keyway, there is a reasonable chance of retrieving it without specialist tools. If the key has snapped flush with the face of the lock — or, worse, fractured inside the barrel itself — it requires the right extraction tools and genuine knowledge of the lock's internal geometry. Attempting to dig out a broken key with a screwdriver, a pen knife or a bobby pin risks pushing the fragment deeper, scoring the inside of the barrel, or damaging the driver pins. That can turn a straightforward extraction job into a full lock replacement, which is why calling a professional locksmith London technician early is always the better course.




