Masterkeying By The Numbers

Articles about masterkeying have appeared dozens of times in Locksmith Ledger. Masterkeying has been the topic of books by well-known people in our industry. Full one or two day classes on masterkeying are regularly presented at almost every locksmith...


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You are now ready to develop a bitting chart and use the plug-in masterkey system. An example of Schlage master key cuts may be: 01014. The master key cut in chamber one is “0”. This leaves change key cut possibilities in the first chamber of 2468. Moving to the second chamber, the example masterkey cut “1”. This leaves change key cut possibilities of 3579. Bitting choices for the remaining chambers are chosen in the same fashion.

The resulting example key bitting array might be:

Masterkey 1: 0 1 0 1 4

2: 2 3 6 5 8

3: 6 9 4 9 0

4: 4 5 2 7 2

5: 8 7 8 3 6

Although this example bitting array shows the change key choices in a set order, any mix of numbers could have been entered. As example, the first space numbers of 2648 could have been arranged differently such as 6284, 4682, etc..

Once you have developed a bitting array, the numbers can be “plugged-in” to the chart. Numbers on the chart do not show actual cuts, but rather show the position of key cuts in your key bitting array. Therefore cuts for key A01 would be taken from position 2 in each space or 23658. Cuts for key A02 would be taken from position 2 except for space 5 which is position 3. Therefore A02 key cuts would be 23650, A03 cuts would be 23652 and A04 cuts would be 23656 .

If needed, HGM (horizontal master keys), VGM (vertical master keys), page master and four page master key cuts are chosen in the same way. In the example bitting array, the VGM 1-16 key is chosen from array positions 22211, or cuts of 23614. If a cylinder is set to the master key and a change key, vertical, horizontal and page master keys designed to operate the chosen change key will function without adding any additional master chips.

The complete plug-in master key system contains 16 pages with 64 codes per page, or a total of 1024 change key codes. The amount of usable combinations depends on the cut numbers chosen for your bitting array and the MAC number used by the lock manufacturer. Generally about 10 percent of the total change key and lower level master key combinations cannot be used no matter what numbers are used for your bitting list.

Page 1 of the plug-in master key system is included with this article. The remaining 15 pages can be downloaded from the Locksmith Ledger website. By choosing a new, original bitting array for each masterkeying job you do, the plug-in masterkey system charts can be used forever. Locks using single-step masterkey systems such as Kwikset can also be applied to these charts by choosing four single-step cut possibilities per chamber.

 

To read additional Locksmith Ledger articles about masterkeying, visit http://tinyurl.com/master0911.

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