How do I get a broken key out of a lock?

Keys snap because they are worn, because they are cheap copies of copies, or because they were being forced to turn a lock that was already jammed. Whatever the cause, the fragment is sitting in a keyway with spring-loaded pins pressing down on it, and the pins are what makes extraction fiddly. Get it out and the underlying reason for the break still needs dealing with.

Safety

What you'll need

• Fine long-nosed pliers or fine tweezers (optional)
• A broken-key extractor, or two fine coping or jigsaw blades (optional)
• A PTFE or graphite lock lubricant
• A strong torch

Step by step

1. Do not turn or force anything.If the cylinder is part-turned, the fragment is trapped by the housing and will not come out at any angle. Very gently try to return the cylinder to its neutral position with the fragment — usually straight up and down — using a fine screwdriver on the fragment's edge, not by twisting.
2. Lubricate before you pull.A PTFE lock spray or powdered graphite into the keyway. It relaxes the pins onto the blade and makes a fragment that would not shift come out easily. This step alone doubles the success rate.
3. Try pliers if anything protrudes.Fine long-nosed pliers or tweezers, gripping as much of the exposed metal as you can. Pull straight out along the axis of the keyway with steady pressure. Do not rock it, twist it or lever against the escutcheon.
4. Use a proper extractor if it is flush or inside.A broken-key extractor is a thin barbed steel strip that slides into the keyway alongside the blade, hooks a cut, and draws it out. They cost very little and they are the right tool. Slide it in above or below the blade, rotate slightly to engage a tooth, and pull both out together.
5. Improvise with two fine saw blades if you must.Two narrow coping-saw or jigsaw blades, teeth facing inwards, slid one each side of the fragment, pushed past a cut and then drawn out together, will grip a fragment. Work gently — the blades are brittle and a snapped blade in the keyway makes everything worse.
6. Stop after two or three attempts.Every failed attempt drives the fragment a little further in and burnishes it. A locksmith with the correct extractors will usually have it out in minutes; the same locksmith called after an hour of poking may have to replace the cylinder.
7. Deal with the cause once it is out.A key does not snap on a healthy lock. Either the key was worn out or the lock was stiff. Cut a fresh key from the original, lubricate the cylinder properly, and check whether the door is under load — a hook bearing on a keep is a very common reason for the extra force that broke the key.
8. Replace the cylinder if it is old.If the fragment came from a cylinder that has been stiff for a while, a new euro cylinder is inexpensive and is a ten-minute job on most doors. Take the chance to check its security rating while you are buying.

Common mistakes

• Superglue on a matchstick or another key — It bonds the fragment to the pins as well as to the tool, and it wicks along the keyway. A cylinder treated this way almost always has to be drilled out and replaced.
• Pushing something in to 'poke it through' — There is nowhere for it to go. The fragment ends up deep in the cylinder where no extractor can reach it, and the lock is then destroyed to open the door.
• Cutting a new key before finding out why the old one broke — The new key will break too. The stiffness that caused it is still there.

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