Someone in Europe started a group recently with the intention of treating lock picking as a hobby or sport. Through their picking conventions and on the internet, they have introduced methods for picking and opening locks to the general public. It is difficult to see what their motives are, but...
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Someone in Europe started a group recently with the intention of treating lock picking as a hobby or sport. Through their picking conventions and on the internet, they have introduced methods for picking and opening locks to the general public. It is difficult to see what their motives are, but the damage has been done. This movement has now emerged in North America beginning with a picking convention held this summer in New York.
One of the results of this convention has been to highlight the procedure of key bumping in order to unlock a cylinder. If you use an internet search engine and ask for “key bumping”, you will find many sites including one which sells nine popular precut bump keys for $14.99. Anyone with a credit card can order the keys.
During the last few weeks, there have been a large amount of calls to our office on this subject. People are asking what key bumping is all about. They are also asking what it means both for our industry and for the security of existing locks in use.
Key bumping depends on Newton’s law that every action has an equal and opposite reaction. When a cue ball on a billiard table is propelled towards another billiard ball, the cue ball stops at impact and the second moves away. Mechanical and electric pick guns use this same principle. By striking a bottom pin in a lock with the momentary force of a pick gun probe, the driver pin reacts by bouncing away from the bottom pin which forms a momentary gap between the two pins. If a pick gun probe strikes all of the bottom pins in a lock at the same time, there will be gaps formed at each tumbler position and the plug can be turned to the unlocked position during that brief instant.
Someone discovered that a cut key could be used to strike the pins instead of using a pick gun. A specially cut key can strike all pins simultaneously which eliminates any guesswork involved with a pick gun. Using Kwikset as an example, the deepest normal cut is a “6”. A Kwikset bump key can be made by code cutting a key with a “6” depth in each space.
The next step is to remove a small amount of metal from the shoulders of the key. A second alternative is to insert the uncut key blank into the code machine vise jaw and align it with the vise jaw key stop. Next, move the shoulder approximately 1/16” away from the key stop (about the thickness of a dime) and tighten the key blank before cutting. In either case the result is that the distance from the shoulder to the center of the first cut has been changed to a longer dimension.
To begin key bumping, the cut key is first inserted fully into the lock and the key is allowed to come to rest. Normal spring pressure which holds the tumblers firmly into the key cuts causes the key blank shoulders to be held a small distance away from the plug due to the lengthened shoulder-to-first space dimensioning.
The unlocking procedure consists of delivering a quick tap to the bump key using a screwdriver handle, small hammer or other light instrument. One manufacturer of locksmith picks has introduced a special tool for tapping bump keys. Unfortunately his tool was somehow obtained for use at the recent New York sport picking convention.
When the bump key is hit, the added dimensioning from shoulder to plug allows the key to move inward a short distance before the shoulder strikes against the plug. During this quick inward movement, the tips between each cut on the key strike the tumblers, exerting upward movement to the bottom pins. A gap can occur between each bottom pin and driver pin because of the Newton action-reaction principle. A very light turning pressure is exerted at the same time the key is being struck. It usually requires multiple releases of tension and taps on the bump key before either the cylinder opens or the mechanic decides that key bumping will not work on this particular lock cylinder.
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