Bump Key – How it Works

The art of lockpicking dates back to ancient times, when primitive anti-theft knots were woven into rope. These knots were designed to either hamper potential thieves, or to detect a theft. The most famous of these was called a “Thief Knot”, which was most commonly used by sailors to detect if their belongings had been tampered with. Today, technology has provided us with a variety of quality locking mechanisms, all of which are designed to protect us from unwanted intrusions.

However, just as security measures have become more advanced, thieves are learning new anti-security methods. A lock picking tool that has recently received a lot of attention is the “Bump Key”, which is said to be able to open over 90% of locks. This tool is easy to make, easy to use, and can open a wide variety of locks in only a few seconds. However, many people aren’t familiar with how a bump key actually works. Once you understand the concept, you can be better prepared to protect your home against intruders.

What is a Bump Key?

A bump key is used in “lock bumping”, a method for opening locked doors. Bump keys are specially crafted, and will work on all locks of a particular type. A bump key is usually crafted from a common metal key, though with different grooves. The notches and grooves in a bump key are uniform, being of the same height. Though the design for bump keys was first patented in 1929 (by a locksmith called H.R. Simpson), it wasn’t until 2002-2003 that bump keys were recognized as a security problem. In 2005, a Dutch television show broadcast a special detailing “lock bumping”, which received widespread publicity.

A typical model for a bump key.

How Does a Bump Key Work?

Inside a lock, there are two distinct pieces to each lock pin. This makes up the “pin stack”. The part of the pin that touches the key is called the “key pin“, while the “driver pin” is attached to the spring that allows the pins to move. When a key is inserted into the lock, it pushes the key and driver pins up, until the small gap between the two pins aligns with the shear line. This allows the pins to separate, and the lock to turn.

A bump key is usually pushed into the lock one notch short of being fully inserted. Then, the key is forced into the lock by an impact force, which can be given with a hammer or screwdriver handle. This pushes the key the full length into the lock, and makes the driver pins “jump” (the key pins stay in place). When this is done in combination with a slight turning motion (rotational force), it can cause the driver pins to be caught above the shear line, which allows the lock to open.

Can a Bump Key Open All Locks?

Some estimates say that over 90% of door locks can be opened with the lock bumping method. However, some locks are more difficult (or impossible) to open with a bump key. Some locks have “security pins”, such as spool pins or mushroom pins, which make lock bumping slightly more difficult. A lock that uses a disc tumbler can’t be bumped, which is used in some higher security locks. .

News Special on “Lock Bumping”