
Why Keys Snap — and Why the Lock Type Changes Everything
Keys break for a combination of reasons: metal fatigue from years of repeated use, a pre-existing hairline crack at the shoulder of the key, forcing a key that was cut slightly off-spec, or attempting to operate a lock whose internal cylinder has seized due to corrosion or lack of lubrication. In Columbia's humid subtropical climate, the heavy moisture and temperature swings between summer highs and cooler winters accelerate the oxidation inside lock cylinders, increasing internal resistance that puts added stress on every turn of the key. When that stress exceeds the key's tensile limit, the shank snaps — often without much warning.
The type of lock the key broke inside determines which extraction technique and tools our technicians select. A standard pin-tumbler door knob lock has a relatively open keyway that may allow fragment access with a thin hooked probe. A mortise lock — the style commonly found in older Columbia commercial buildings along Main Street and in historic renovated properties in the Elmwood Park neighborhood — has a more complex cylinder housing that sits recessed inside a thick door edge. That geometry changes the extraction angle entirely. Automotive ignition cylinders add another layer of complexity, since the fragment can migrate deeper when the driver attempts to crank the engine after the break. This is precisely why attempting DIY extraction with bobby pins, super glue, or paperclips almost always makes the job harder and the lock more likely to need replacement.

