Have you ever had trouble getting a copy of a key to work in your locks?
In order to understand why, you need to understand how a key and lock works.
It's a lot easier to show something like this than to explain it. But basically the bumps on the key match the pins of a corresponding size. When the correct key is inserted, the pins all line up exactly with the edge of the cylinder and it will turn. Take a look at the video below.
This helps to explain why a worn or damaged key won't work well. If you purchase new locks or a new house, I always recommend keeping one of the new keys stashed away and unused so that you can make copies from it. Imagine this - every time you insert a key, it rubs on the tumblers in the lock and wears the key down. Even just bouncing around in your pocket or purse can slowly wear the clean edges off of a key. Then years later you take the key to the store and have a copy made only to find that the new copy does not work. This is often because the key you made the copy from is warn slightly down and copied key now allows the pins in the lock to set just slightly lower than they did before and keeps the lock from opening. Of course, the guys behind the counter needs to understand how to use the key cutting machine as well, but there is not much I can do to help you out there.
Thanks to Stian Berg Larsen for this video
Click here to visit his You Tube page fore more cool animations