Key Bumping Makes the News

The theory behind key bumping is real, but in actual practice key bumping is not always successful. The first problem is with the timing in “catching” the gap. Very light turning pressure may allow the top and bottom pins to rejoin contact. Heavy turning pressure does not allow the pins to separate.

A second problem can be the actual key combination. If the combination of the lock contains some of the deeper cuts, those long bottom tumblers will be moved across the shearline during the bumping process and there will be little or no opportunity to turn the lock open. A video on the internet available at www.toool.nl shows an 11-year-old girl at the New York picking convention who hit the bump key only twice before a Kwikset lock opened. It would be interesting to know what the cut combination was for that particular Kwikset lock. One can almost guess that it contained all shallow cuts either deliberately or by accident.

I am reminded of a locksmith who gave a class several years ago on servicing foreign car locks. He sold homemade cut keys which could pick open Jaguar Tibbe locks in a fews seconds. He had several Tibbe locks which were passed around the room and everyone immediately unlocked the locks using his special keys. I later tried unsuccessfully to open several different Jaguar Tibbe locks with one of his keys. I discovered that the only Tibbe locks that could generally be opened were those which had a combination using just one ‘3’ cut and that ‘3’ cut had to be in the first position of the combination. By prearranging cuts in the trial locks, the picking key worked, but it rarely worked on the job when it really counted.

A third problem is the possible damage done to the lock. Each time the key is bumped, or hit, the shoulder is pounded into the lock plug and the tumblers are being violently pushed horizontally as well as vertically. Tumbler holes, especially in soft material such as die cast, could become egg-shaped after repeated bumping. You could end up with a damaged lock plus a door that is still locked.

It is true that key bumping is a possible alternative for opening a percentage of pin tumbler locks. Lock picking is also an alternative for opening many types of locks. Both unlocking techniques may open a particular cylinder but there is no guarantee that either technique will always accomplish the job. The real problem with key bumping is that there is very little training needed to teach someone how to beat the dickens out of a lock with a bump key.

We do have many solutions for key bumping in the locksmith community and they are called high security locks. Bump keys usually only work on lock systems which have a single action such as with standard cylinders where tumblers are moved to a shearline. Most high security cylinders have at least two actions, primarily moving tumblers to the shearline plus a second action involving sidebars or side pins . There are also high security locks which use other systems such as rotating parts or magnets which are also not generally susceptible to key bumping.

LAB was contacted for their ideas regarding special driver pins that might be available to deter key bumping. LAB introduced grooved driver pins in 1983 which are designed to ‘lock up’ and resist movement of the driver pins whenever turning pressure is exerted on a lock plug. Regular vertical pin movement, such as when inserting an operating key, is not affected. LAB is currently undertaking trials of their grooved driver pins and other driver pin designs in order to provide answers to the threat from key bumping. Locksmith Ledger will report on their findings when available.

In addition to key bumping, the locksmith profession is also under siege from nationwide companies with high priced charges for lockouts. Their employees reportedly use battery operated drills more often than lock picks. As with key bumping, it takes just a few minutes to train an amateur about where to drill for the cylinder shearline. For a few extra cents, manufacturers could install a hardened washer behind the face of lock plugs. While not a complete prevention, at least it could slow down or deter these amateur newcomers.