Why Keys Snap and What Happens Inside the Lock
Keys are subject to cumulative metal fatigue every time they are inserted, turned, and withdrawn. Grandview winters — with their freeze-thaw cycles — accelerate this process because moisture works into the keyway, causes slight corrosion, and increases the torque required to turn the cylinder. A key that has been slightly bent from years of a heavy keychain, or one that was cut on a worn blank to begin with, can fracture at the shoulder or at a deep cut along the blade. The moment it breaks under turning pressure, the fragment is usually rotated partially into the shear line, making removal anything but straightforward.
Inside a pin-tumbler or mortise lock cylinder, the broken fragment often sits in contact with the driver pins. In a vehicle ignition, the wafer stack holds the piece under spring tension. In either scenario, pulling the fragment straight out with household pliers almost always pushes it deeper, damages the keyway warding, or scratches the cylinder walls — damage that can turn a simple extraction job into a full cylinder replacement. That is why calling a skilled professional at the first sign of a break is the right move, not the cautious one.