If a newly copied key doesn't work, bring back both the copy and the original key it was cut from, plus a clear description of how the copy fails: it won't go in, goes in but won't turn, turns only with force, or works some of the time. Try both keys at the actual door first, because how the original behaves in that lock tells the locksmith where to look.
The copy, the original, and a description
A copy on its own shows only half the picture. A duplicate key is made by tracing the original's cuts, the notches along the blade that lift the pins inside the lock to the right height. With both keys together, the cuts can be compared directly. Without the original, there is nothing to measure the copy against.
Your description matters just as much as the keys. "It doesn't work" gives nothing to go on. "It slides all the way into the deadbolt but stops after a quarter turn" narrows the search right away.
Test both keys in the same lock before you leave
Do the comparison at the door the copy is meant for. Try the original first, then the copy, in the same lock, and pay attention to how each one feels. Write down which lock you tested. A knob, a deadbolt, and a mailbox can take different keys even when the keys look alike.
Test once with the door open and once with it closed. If the bolt turns freely with the door open but drags when the door is shut, the bolt is pressing against the strike plate, the metal plate on the frame that the bolt slides into. That points to the door, not the key.
For the copy, note what you see and feel:
- Whether it slides in fully, so the shoulder (the small step near the head of the key) rests against the face of the lock
- Whether it turns all the way, partway, or not at all
- Whether it turns only when you push hard or jiggle it
- Whether it drags or catches on the way out
- Whether it works on some tries and fails on others
Then note the same things for the original. An original that turns smoothly next to a copy that doesn't is a strong lead.
How each symptom points to the copy, the original, or the lock
A copy that won't go in, or stops short of the shoulder, usually doesn't match the keyway, the shaped slot the key slides into. A rough edge left from cutting can do the same. Either way, the copy is the likely source.
A copy that goes in fully but won't turn, while the original turns easily in the same lock, most likely has a cut that doesn't match. One notch slightly too deep or too shallow is enough to leave a pin in the way. A copy that turns only with force or jiggling usually has the same problem on a smaller scale, or a burr, a tiny raised edge of metal on the blade.
If the original also feels stiff or needs a wiggle, the copy may be faithful to a worn original. A duplicate reproduces the wear along with the cuts, and small errors add up.
The lock or door is the likely source when both keys feel rough, when both work with the door open but struggle with it closed, or when you have to push or lift the door before the bolt moves. A copy that works some days and not others can go either way, so describe the pattern. None of these is a diagnosis without someone looking at the keys and the lock, but each tells you where the problem most likely sits.
What not to do before you go back
Don't force a copy that won't turn. Twisting hard is how a key blade snaps off inside the cylinder, and then a key problem becomes a lock problem. Filing or bending the copy to make it fit is just as risky, because it changes the very cuts that need to be compared. Hold off on spraying oil or any other lubricant into the lock, too. Some products collect grit, and the residue makes the original symptom harder to read.
If the copy is meant for a different lock than the one the original usually opens, bring both keys and say which lock each one is supposed to work in.
When the side-by-side test points to the lock, the follow-up changes. A stiff or misaligned lock calls for door hardware repair, and a worn cylinder may need rekeying or replacing. Upper East Locksmith handles key cutting and duplication along with that lock and door work, so you can call (347) 444-9725 to describe what you found.
Frequently asked questions
Is it normal for a new copy to need a second cut?
A new key copy sometimes needs a second cut. Duplication traces the original, so a slightly worn original or a small tracing error carries straight into the copy. A failed first copy is not unusual, and on its own it doesn't mean the lock is damaged. It usually means the cuts on the copy and the original need a closer comparison.
Can a copy work in one lock but not another?
A copied key can open one lock and fail in another if those locks were never set up to take the same key, or if one lock is more worn than the other. If the original opens both locks smoothly but the copy opens only one, the copy is the more likely problem.
What if I no longer have the original key?
Without the original key, a failed copy can't be checked against the key it was traced from. Bring the copy anyway, along with which door and which lock it's for and exactly how it behaves. If no working key exists for that lock, rekeying the lock so it takes a new key is a common route.
Should I stop using the original if the copy fails?
Keep using the original key if it still turns smoothly, and hold onto it, since it's the reference for any new copy. If the original also feels stiff or needs jiggling, don't force it. That roughness points toward wear in the key or the lock, and the same twisting that snaps a copy can snap the original.