What to Look for When Buying a Bump Key

A bump key is a tool used by locksmiths to open certain types of tumbler locks. The first bump key was created in 1926 but did not come into wide use until the 1970’s.

Until 2002, lock bumping was only done by locksmiths. The Open Organizations Of Lockpickers (TOOOL) drafted a white paper detailing the uses, techniques, and hazards of lock bumping that was published in 2005. This information made it possible for the average homeowner to change the tumblers in his lock if he lost the keys or wanted to change the locks for whatever reason.

Tumbler locks have a set of tumblers of different sizes as shown in picture below. A key pushes the tumblers up until the bottom of the tumblers is level. This is called the shear line. When the bottom of the tumblers is aligned the lock can rotate.

Each lock has a different set of tumblers with different sizes and positions so that each key is unique. Master keys can be used in all locks that use certain combinations of tumblers because they push up the tumblers regardless of the specific combination so the shear line is level.

To bump a lock you need a “bump key”. The picture below shows a typical bump key with a door key whose lock it can be used to bump.

The bump key must have the same blank key profile as the lock it is being used to open. So one of the first things you need to look for is the blank number on the bump key. The difference between a bump key and a master key is that a bump key requires force and a certain amount of skill to make it work.

Bump keys are keys that have all of the cuts made to the deepest level required for a particular model of lock. It is also necessary to remove a little bit of the metal on the tip and the shoulder of the key as well. The shoulder of a key is the part of the key that prevents the key from entering the lock too deeply as shown in the picture below.

The bump key is inserted into the lock and then “tapped” with a hammer which causes the tumblers to bounce and when the bottoms get level the cylinder will turn and the lock will open.

Follow these steps to determine which bump key is required for your lock:

• If you have the actual key, compare it to the bump key.

• Most locks have the name and model of the lock stamped on it. Write the information down and use it to select the correct bump key

• Get a bump key set that covers a lot of different locks. The larger the set, the more likely it will have the one you need.

• Practice using it until you get good at it.

To learn more about lock bumping go to www.bumpkey.us