Does this scenario sound familiar? You have lived in your home for many years but haven’t changed the locks since you moved in. Over time, you lost the original keys that came with your lock and as a result, you have made many duplicate house keys along the way. Unfortunately, when duplicating a duplicate key (or duplicating a duplicate of a duplicate key etc), it may not work. This is because each duplication adds its own imperfections resulting in each generation of copies moving slightly farther away from the original pattern. First Lock & Security Technologies outlines some of the reasons why and what to do next if you find yourself in this predicament!

Do You Copy the Right Key?

When a duplicate key you just had made doesn’t fit the lock, the first thing to consider is that you copied the wrong key. It sounds quite daft, but it is actually a common mistake. Many keys look so similar that people often end up cutting the wrong key. For example, after finding that the key copy does not work in their front door, they may find it fits the back door!

What is the Lock & Key Relationship?

In order to operate a lock, the unique pattern of cuts on the key blade must precisely coordinate with the original manufacturer’s specifications. Key cuts need to be precise, so they can move the pin to the right place to allow the lock to turn. Unfortunately, over time and use, keys can become so worn that the profile of peaks and valleys no longer “fits” the lock. In addition to wear, keys can also become bent. When you make a copy of a worn or damaged key, the new key cut is a replica of the worn or damaged key, not the brand new, pristine original.

Duplicate House Keys Are Not Exact Key Copies

The most accurate method of duplicating a house key is with a code. Original keys that come with locks typically have codes on them, called bitting codes or key cuts, that correspond to the depth each cut on the key must have in order to match the pins inside the lock. The key may show the actual key cuts, or it may display a blind code. To get the actual bitting code from a blind code, a special directory that is only available to licensed locksmiths is required. When the key code is not available, a key can be duplicated by tracing its pattern. Or the key can be de-coded by a locksmith to determine the original manufacturer’s specifications and produced on a code cutting machine or a key punch. As a final resort the lock can be taken off the door and brought in to a locksmith for de-coding, or of course we can come out and perform the service.

Can You Make Sure that Duplicate Keys Will Always Work?

When you get a new lock, it is always best to put one original key somewhere safe and not use it. Keep this key as your original key from which all duplicates will be made. As you do not use this key, it will not get worn and rather will stay as crisp and perfect as the day you got it. This will mean that all duplicate keys will be as close to perfect as possible and you will avoid the continual degradation of replacement keys.

Should I Buy New Locks or Rekey My Existing Locking System?

If you have made many copies of your keys over the years and you do not know where they all are now, it is definitely time to consider rekeying the lock. Key control is an important component of home security. No matter how high the quality and condition of your lock is, if you do not know who has a key, you may be leaving yourself open to harm. Changing the locks is a small price to pay for peace of mind.

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To summarize, as you make new duplicates from continually less perfect copies, eventually the duplicate keys become different enough from the original that they won’t work in the lock. If you did not stash away an original key at the time your locks were changed and instead only have copies of key copies; it may be time to start over by rekeying or replacing your locks or having your key de-coded. Keep one house key as your original for the best chance in making duplicate keys as needed for the future and call us for all your lock and key needs!