A bent or worn key can sometimes be copied, but a standard duplicate is traced from the original, so the new key can pick up the same rounded cuts or crooked blade. Whether a usable copy is possible depends on how damaged the key is and whether a less-worn key from the same set exists. A copy of a damaged key is never certain to work until it is tried in the lock.
Why a copy inherits the original key's damage
A standard key duplicating machine copies by tracing. A guide follows the edge of your key while a cutter shapes a blank to match, so the new key can only be as accurate as the original. Rounded cuts on the original become rounded cuts on the copy. A bent blade throws the trace off, so the depths come out wrong.
Those cuts matter because many door locks use a pin tumbler design: a row of small spring-loaded pins inside the cylinder. Each cut lifts one pin to a set height, and the lock turns only when all the pins line up together. A worn cut lifts its pin a little short. The worn key may still work in a lock that has worn along with it, but a copy made from it starts slightly off.
Copies of copies drift further. Each round of tracing adds a little error, so a key cut from a duplicate of a worn key can end up binding or refusing to turn.
Bent, worn, or just hard to turn?
A bent key has changed shape. The blade, the long part that enters the lock, no longer runs straight from the bow, the part you hold. Lay the key flat on a table and look along it at eye level. If it rocks or shows a gap under the blade, it is bent. Check from the side too, since some bends are twists.
A worn key keeps its shape but loses its edges. The peaks between cuts look rounded or flat, the valleys look shallow, and the cut edge often looks polished. Wear shows up most clearly when you hold the key next to a less-used key from the same set.
A key that looks fine but needs jiggling may not be the problem at all. Try another key from the same set. If that one turns smoothly, the original key is the likely cause. If both stick, the lock is the more likely cause, and a fresh copy probably will not fix it. A key that turns easily with the door open but drags with it closed usually means the latch is rubbing on the strike plate, the metal plate on the frame. That is a door hardware issue, not a key issue.
What to do before you ask for a duplicate
- Stop forcing the key. A blade under strain can snap inside the lock, which turns a simple copy into a bigger job. Do not try to straighten it yourself.
- Note how the key behaves: whether it goes in fully, turns smoothly or needs jiggling, or works in one lock but not in another it should open.
- Find any other key from the same set. A spare in a drawer, or one a housemate or employee rarely uses, is usually less worn, and a less-worn key is a better template.
- Pick the template. If one key is still straight with crisp cuts, copy that one. If every key is damaged, ask about other options instead.
Those options are rekeying or replacing the lock. Rekeying means changing the small pins inside so the lock works with a freshly cut key, and the old keys stop working. Replacement means a new lock. Either way, you stop copying a key that keeps getting worse.
What to hand over when you ask for a copy
- The damaged key, even if you plan to retire it.
- Every other key from the same set, including ones that seem worse. Several keys side by side show which cuts have worn.
- Any markings on the bow, such as numbers, letters, or text like 'do not duplicate'. Restricted and high-security keys may need a different process from a standard duplicate, so point these out at the start.
- Which lock the key fits, such as an apartment deadbolt, a mailbox, or a storefront door.
- For a building or business key, the name of the person who manages the key set.
If you are unsure whether a key is worth copying, call Upper East Locksmith at (347) 444-9725 and describe it first. If you plan to bring the key to 1450 1st Ave, New York, NY 10021, hours are Monday through Saturday, 8 AM to 6 PM. The business is closed Sunday.
Frequently asked questions
Should I keep using a bent key while I wait for a copy?
If you have a spare, use it instead of the bent key. A bent key flexes at its weakest point each time it turns, and a key that snaps inside a lock is harder to deal with than a crooked one. Keep the bent key rather than throwing it away, since it is still useful for comparison when the copy is made.
Does it help to bring the lock or just the key?
For a duplicate, the key matters most, and a short description of how it behaves in the lock fills in the rest. A portable lock such as a padlock is easy to bring along if all its keys are worn. Do not remove a lock from a door just for this. A clear photo of the front of the lock does the same job without taking anything apart.
What if my key has a stamp saying not to duplicate it?
A key stamped 'do not duplicate', or carrying other restriction markings, belongs to a system that may handle copies differently from a standard duplicate. If the key came from a building or employer, talk to the person who manages that key set before asking for a copy, and mention the stamp as soon as you hand the key over.
Can a property manager or business owner request copies of a worn key for multiple doors?
A property manager or business owner can ask about copies for several doors. A worn key makes a poor template for a batch, though, because every copy inherits the same wear. Bring the least-worn key for each lock and label each one by door. If most keys across a building are badly worn, rekeying those locks may make more sense than copying.