Roadside service providers have done a lot of good things for locksmiths. For years they have been supplying many of us with a steady stream of business and a quick and easy source for automotive key codes. Unfortunately, a few people abused the key code service and now it has become much more...
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In other cases, it is possible to get part of the information needed to make the key by disassembling a glove box or compartment lock that is readily accessible. Once that has been done, the remaining cuts can be obtained by a variety of methods including impressioning, progression, tryout keys, wafer reading and using decoders.
4. Decoding and/or Progressing
Learning to "read" wafer-tumbler locks can make your life a lot simpler, but it does require visual acuity and the use of a magnifying scope. This topic was recently covered in detail so let's go on to using decoding tools to accomplish the same thing.
To understand how the decoding tools work, it is first necessary to understand wafer lock construction and the factors that allow the tools to work in the first place. Photo 1 shows a typical wafer tumbler. The three letters refer to different parts of the wafer; each part plays a role in the operation of most decoders. Let's take a look at what these parts are and how they make decoding tools possible.
Part A is the uppermost portion of the tumbler, and this part contacts the inner surface of the lock housing when the tumbler is in the "rest" position. For the purposes of this article, the rest position is the normal position of the tumbler when there is no key in the lock. The pressure of the spring pushes the tumbler up until part "A" contacts the inside of the lock housing, at which point the tumbler can go no further. (The terms "up" and "down" as I am using them here are relative only to the photo and in reality the lock could be mounted in any position.)
Part B is the spring tab. The spring maintains tension between this tab and the base of the chamber that contains the spring. In the rest position, the spring is as fully extended as possible inside the lock.
Part C is the lower portion of the tumbler. The width of this portion determines the depth of the cut on the key. The wider this portion is, the deeper the cut will be. It is this portion of the tumbler that the decoding devices measure in order to decode the lock. The part of the tumbler that contacts the key is often referred to as the "key landing", or just as the "landing."
All three of the decoders that I'll be discussing in this article measure Part C of the tumbler in one way or another in order to decode the lock. Two of the decoders, the EEZ Reader and the Kobra Reader, go about measuring Part C in essentially the same manner, while the Determinator approaches the problem from a different angle.
In visual key reading, you would gauge the relative positions of the key landings of Part C of the tumblers against one another to determine the cuts. Using a decoder allows you to do the same job without the necessity of peering into the lock. Even with the best of lighting conditions and the best of scopes, it is often difficult to see the tumblers at the back of the keyway. A decoder essentially moves the measurement process to the outside of the lock, which makes the job much easier for many people.
Photo 2 shows two different tumblers from the same lock. The tumbler on the left has the shallowest cut and the tumbler on the right has the deepest cut in the system. By measuring the difference in the position of the key landing between the two tumblers, portion "D," we can determine the difference in the depths of the two tumblers. As we can see by the numbers stamped on the tumblers, there are six different cuts in this particular system. This means that determining the difference between a number two and number three cut boils down to being able to determine one-sixth of dimension "D." This can be tricky to do visually, especially with the tumblers at the rear of the keyway.
Photo 3 shows a set of four tumblers from a typical automotive system arranged so that you can see the progression of the different depths. It is these differences that all of the decoders measure. Keep in mind that all of the measurements of the tumblers are made assuming that point "A" on the tumbler is at rest against the inside of the lock housing which will align all of the tumblers as they are in the photo. As you use any of the tools, or attempt to sight read the lock, always make sure that the individual tumblers are not bound in any way. Otherwise you will get false or misleading readings.
Using the EEZ Reader
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