How to Identify a Bad Key Copy

Last Updated: June 29, 2021

Have you ever wondered if the key you got copied from a hardware store or a lock shop wouldn't work when you used it in your door? It's a frequent problem. This guide will teach you how to identify bad key copies before you even leave the store, and it might help you ask the right questions and provide the right information to avoid getting a bad copy in the first place.

Steps

1
Do the keys line up side by side? The easiest way to tell if a key is bad is that if it does not line or match up with the grooves and the shoulders on your original key.
2
Is it the correct key blank? On many basic keys, there are numbers you can check on the shoulder or the front head of the key. On normal house keys, a number might look like SC-1 or KW-1.^{[1]
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3
Could the key even be copied? Sometimes stores try to copy keys that cannot be copied on normal blanks. Certain types of keys cannot be copied by regular locksmiths, such as ones for Primus locks and ones meant for college dorm rooms and apartments.
4
If it was a car key, did you tell the company the make and model? It's very easy for larger department stores to screw up your key if you don't tell them the year or model car you have. Also, some newer models of cars have electronics inside, and car doors or the ignition may not work if you copy them from a regular key blank.
5
Is the clerk confident that he or she did it right? You can sometimes tell if the clerk is not certain whether the key will work. Sometimes, if the clerk takes a long time, or no time at all, he or she may have chosen an incorrect key blank.
6
Has the original key become worn from use? Years of use in the lock causes wear in an original key, possibly causing it to not be able to be copied correctly. If this is the case then an original key will have to be made.
- Note that it's generally the flat parts, not the pointed corners, that operate the lock, so a key with some wear may still copy correctly.
7
Is it a copy of a copy? If you copy a key based on copies, they will slowly gain more errors. After the fifth generation of copies, those keys may fail to work in your lock, or work improperly.
8
Was it copied locally? Many times, locally owned businesses copy keys better than department stores. It may cost a bit more, but it's definitely worth it.
9
Was your original key broken or bent? You can sometimes copy a key from a broken or bent key. A locksmith needs to find out the numbered combination of your lock and needs to cut you an entire new one if it is broken in a bad spot or if the machine cannot grip the broken pieces.

Community Q&A

Question

How can I identify every key when they all look the same?

Community Answer

Find out what each key goes too and mark them with different stickers.
Question

Can you tell if a key has been copied?

Community Answer

Copied keys will have a extra line on the outside, but this can only be seen with a magnifying glass.
Question

Is the quality of the copied key related to the price of copying a key?

Community Answer

In short, yes. The price of the copy is based on materials, design, and handiwork. A local locksmith will often be able to do a better job than a department store, though it will typically cost more.

Warnings

If you are trained to make keys, always wear eye protection and beware of brass splinters.

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Do not copy keys yourself. Key copying machines have a dangerous, fast-spinning blade to cut keys with. Most hardware stores and lock shops have staff who will copy a key for you at a modest cost.

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