Key Bumping
4/2/2009 9:16:52 AM by (radishfarmer)

Key Bumping

by Beartrace

In the Urban Escape and Evasion course students are taught introductory lock pick skills. These skills are important, but it takes time to become truly proficient. A lock pick set is portable, some are similar to folding pocket knives, so one can easily carry these tools in a 'go bag.' However, there is another technique which is invariably faster and easier than using lock picks. This technique has been around for about a 100 years, yet is still not widely known. This centurion technique is called key bumping.

Most key locks use the same principle. The plug includes a row of pins perpendicular to the keyway. When the key is inserted the little peaks on the key raise the pins. The sliders have different length. Each pin is divided into two pieces. The length of the pins relates to the height of the peak on the key. When the correct key is inserted the pins are all raised to a point called the shear line, the point where the break points of the pins are all aligned - the key can then rotate, and the lock opens. This is the same whether a door lock or a padlock.

Key bumping takes into consideration a little trick of physics. The bump key has a row of peaks and valleys like a regular key, except they are cut at the lowest points. These are easily made at home, or can be purchased. The bump key is inserted all of the way, then pulled back slightly (one peak back from complete insertion.) While a light turning pressure is placed on the key, a hammer or something similar is used to tap the key. As the pins are popped up by the key being hit to complete depth they will align briefly, the slight pressure allows the bump key to rotate and open the lock. (Note, there are locks which claim to be bump proof, and these are also very difficult to pick)

Any student of the Urban Escape and Evasion course could easily add this information to their skill database. Since the keys can easily be made with common tools, some of which are in many 'go bags' - this would be a practical and clever addition. More information about bumping can be found on YouTube.