Well, lets start with a little history first. Although most people believe that a bump-key is new, it appears to have been patented in 1928 by H.R. Simpson, who had called it a “rapping” key.  In the 1970s locksmiths in Denmark shared a similar “bumping” technique for knocking on a lock cylinder while applying slight pressure to the back of the lock plug. When the pins would jump inside of the cylinder, due to the force being applied, when they reached the shear line the plug would be able to slide out freely allowing a locksmith to disassemble the lock quickly.

How a pin tumbler lock works: A pin tumbler lock is composed of a series of spring-loaded stacks called pin stacks. Unless “master-keyed”, each pin stack is composed of two pins that are stacked one on top of each other: the bottom pin, which touches the key when it is inserted, and the top pin, which is spring driven. When the proper key is inserted into the lock, all of the bottom pins and top pins align along the "shear line," allowing the cylinder plug to turn. When no key or the wrong key is in the lock, pin misalignment prevents the cylinder from turning.

How “bumping” a lock works: When bumping a lock, a specially-cut key is partially inserted into the lock's keyway. Tapping or “bumping” the key inward forces it deeper into the keyway, and since slight turning pressure is applied while doing this, when the pins “jump” they reach the “shear line”. Lock bumping takes only an instant to open the lock. Some people claim that this “bumping” does not damage the lock in any way, however, I disagree. When you tap or “bump” the key, the key will strike the face of the lock causing it to dent slightly. So, repeated bumping will change the lock's spacing characteristics causing the original key to not operate the lock properly. Only a rare few key-pin locks cannot be bumped.

How can you protect yourself from “bumping”?  You can run out and purchase all new locks that are “Bump Proof”. But who can afford that? Or you can call A Simmons Locksmith at 401-274-2539 today and have us convert your existing locks to “bump-resistant” status by utilizing special “spool” or “mushroom” top pins.