![]() ![]() If a MK cut is an even number in the first chamber, all cuts used in the first chamber will be even. The two-step means that for each given cut of the master key, every other available cut is used in the progression of the system. In most common 10-depth, two-step systems the cuts range from a shallowest cut of 0 to a deepest cut of 9 for a total of 10 available depths. In a fully progressed system each chamber uses all of the cuts available in that manufacturer’s system. If the old keys had a constant in the first chamber, use the fifth or sixth chamber in the new one for constants. In a partially progressed system, alternate the chambers carrying constant values. What kind of patterns do you see? Using higher cuts where there were low cuts helps assure that no key from the old system will work any lock in the new system. ![]() If you are initiating a new system, be sure to examine the cuts of the old system. By a simple keystroke, you can write and evaluate the feasibility of a new system or rewrite it easily before putting it into use. A computerized system will allow you to experiment by changing the number and position of constants carried and the order of progression. Even in a computerized system the progression sequence must considered. In a hand written system, you may be a couple of pages into it before you discover a large amount of undesirable key cuts. Some systems today are still hand written on the job. A small 64-cut system might be adequate, or if there is a lot of re-keying expected, you might go to the next level with a 256 cut system. You wouldn’t want to write a fully progressed 4096 cut system for a 30-unit office building. Ask your customers how often tenants move in and out see if they are planning on adding new doors or buildings, etc. When a system is initially written, the size of the system should be adequate to fit the customer’s needs today and allow for future re-keying and adding new locks into the system. The system size you need is determined by how many individual keys your customer needs now and by allowing for future growth of the system. Know the limitations of the system you are using. Many manufacturers specify a MACS of 7 values between adjacent cuts. A nine cut next to a zero will cut off too much of the adjacent material of the key blank to allow a zero pin to seat properly. A key with cuts of 7-3-8-9-0-9 isn’t possible in most systems because of the Maximum Adjacent Cut Specification (MACS) rule, also known as the maximum allowable cut. For example, although easily cut, a key with cuts of 1-1-1-1-1-1 isn’t a good key to issue. Following are some things to consider.Ī fully progressed two-step 6-pin system will yield a maximum of 4096 cuts while a fully progressed 5-pin system will result in a maximum array of 1024 cut combinations. When you are designing, implementing or servicing master keyed locks, it is essential to remember the limitations of a master key system. Either by picking, key manipulation or simple key insertion, unauthorized access may be granted. In addition to the two intended keys, dozens of other cut combinations may work that lock, resulting in an uncontrolled loss of security. By keying a cylinder to fit two random keys, you can create a cylinder with dozens of shear lines. Each additional shear line added further reduces the security level. When the number of shear lines increases, security decreases. Master pins are added to this stack to create additional shear lines. Each pin stack consists of a spring, top pin or driver and bottom pin. In standard mechanical master keying a primary fundamental is that master keying is a controlled loss of security. For the purposes of this article the term ‘master key’ refers to the top or highest level in the system. In addition to electronics, various high security lock manufacturers offer second and third level locking components that further reduce the loss of security, but in many instances it is a matter of expense that determines the continued use of simple pin tumbler locks in a system. In the commercial and residential world there are multiple advantages to electronic security, but common pin tumbler locks and master keying are still widely used. Even the keyed ignition switch is disappearing. Fewer and fewer cars each year have keyed cylinders in the trunk, doors or glove box. Specifically in the automotive industry we have seen continuing progress in the reduction and elimination of mechanical keyed cylinders.
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