Why Keys Break Inside Locks — and Why the Lock Type Matters
Keys do not usually snap without reason. The most common culprits are an aging, worn key that has been duplicated one too many times, a lock cylinder that has become stiff due to lack of lubrication or internal wear, and the very human instinct to force a stuck lock instead of stopping to assess the problem. Cold snaps — even the mild winters Charlotte occasionally sees — can cause metal to contract and make keys more brittle, and the combination of a weakened key and a frozen lock is a recipe for a break. Position matters too: a key that snaps flush with the keyway face presents a very different technical challenge than one that breaks with a small amount of metal still protruding from the cylinder.
The type of lock also determines the extraction method and the overall complexity of the job. A standard residential door knob lock has a relatively simple pin-tumbler cylinder, while a mortise lock — common in older Charlotte bungalows in Plaza Midwood, high-end residential entryways, and virtually every serious commercial door — houses its cylinder inside a larger, multi-function lock body that controls the latch, deadbolt, and sometimes a privacy function all in one unit. Extracting a broken key from a mortise lock cylinder requires care not to disturb the internal cam or tailpiece, which is why this is a job for an experienced technician rather than a trial-and-error DIY attempt with improvised tools.