How Does a Bump Key Work?

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Finding out about bump keys and alternative ways to get into locks can make any feel unsafe. The misinterpretation is that some universal key, that when used in conjunction with a hammer opens any lock. Of course, this is not the case. Bump keys may be quite easy to use, but they require some knowledge. Automobiles are one of those limitations. But why won’t the bump keys work on cars? In order to understand, it is necessary to understand how everything is supposed to work. (We will do our best to keep it simple.)

The Details

A Bump Key is most often associated with a standard pin tumbler lock. A very basic explanation of how it works requires a cursory understanding of a basic lock; A lock opens when the correct key is inserted and stays locked if the incorrect key is used. This is because the correct key will orient the internal components so that bolts, ca be retracted. In the case of a basic pin tumbler lock, the lock uses several stacks of pins. In each stack, there is a key pin (bottom pin), a driver pin (top pin), and a spring (above the top pin). These key pins very in lengths. So now that we have the basic components, we need to know the basic parts of the lock.

There are two parts of a pin tumbler lock, the plug and the bible. The plug is a cylinder that the key is inserted into, and the bible is the housing for that plug. When a key elevates the pins properly, the driver pins and springs will reset in the bible, and the key pins will reset in the plug. The line that separates the plug from the bible is called the shear line (remember that, its important). Once the different pin types are separated by that shear line, the plug can rotate, and that will open the lock.

Locksmith Key Terms

Key pin- the bottom pins that the key touches directly. The key pins are different sizes. When the correct key is inserted, all of the key pins will reset in the plug.

Driver pin- The top pins in the key stack that touch the springs directly. The driver pins are a uniform height. When the correct key is insert, all driver pins will rest in the bible.

Bible– The housing for the plug. The bible will hold the driver pins and springs when the pins are at the shear line.

Plug– The plug has the key way. It will rotate once the pins are at the shear line. When everything has reached the shear line, the plug will house the key pins

Shear line– The line that represents the boundary between the plug and the bible. When the lock opens, the pins are said to have reached the shear line.

How to Use the Bump Key

Basically, what a bump key will do is move the pins to either side of the shear line for and instant. First the bump key is placed in the lock. Pit if all the way in, make sure it is touching all pins. Pull it out one click. If you cannot hear the click, look for the beginning of the first groove closest to the bow (flat part that you turn with your thumb and index finger) of the key. Strike the bow of the key with a hammer as you turn the key in the lock. what this process is doing, is striking all of the key pins with enough kinetic energy to send the pin stacks flying up into the bible. The hope is that when you turn the key you will be turning it when the drivers are above the shear line and the key pins are below. Because this method relies quite a bit on luck, it helps to try several times.

The key itself must be mortified from a key that would fit the lock it is being used for. That means that a Schlage lock requires a bump key made from a Schlage key, a Kwikset lock requires a bump key made from a Kwikset key ect… Once you have a key that will fit into your lock, regardless of whether it will open the lock, you can make a bump key. The only trick is making sure your key is long enough for the lock. Some brands have 5 pin and 6 pin locks. Without manipulating all the pins in a lock, a bump key is useless. Also the internal components will nee to have a predecided direction to be moved.In this case, all of them are being moved up, because that is the only direction they can move.


We hope this was educational. Please stay tuned for more information from the pro himself. Sure-Lock





2 thoughts on “How Does a Bump Key Work?

    How a Car Lock Works – Sure- Lock Homes Blog said:
    May 2, 2016 at 2:38 pm

    […] would happen if you tried a bump key on a […]


    […] the need for a locksmith, it only increases said need. For those of you who still think you can pick a door while drunk, how do you expect to do that if you can’t even use a key? However, people have still […]


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