Developing Floor Master Keys Within Existing Master Key Systems

Two different methods can be applied to develop sub-master keys within an existing master key system: a traditional method and the unconventional “guerilla” approach, designed to get maximum results from minimum resources.

Locksmiths are often called out to rekey areas where an existing master key system is in place. Many times records relating to these systems are outdated, unclear, or incomplete. When starting a new master key system is out of the question, it is up to the locksmith to either pass on the job...

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Note: One of the keys in the set (19) has a key bitting of 901892. It isn't possible to cut this key using a standard cutter. Be prepared to fit your code machines with a special cutter designed to overcome the normal “safety factor.”

Figure 10 demonstrates how to develop diagnostic keys.


The advantages of diagnostic keys are:

1. The keys do not have to be prepared in the field.

2. The keys take out all the guess work as to how a cylinder is keyed

3. The keys will be used later on for other services.

4. The time allotted to cutting these keys is predictable, taking the guesswork out of how to bill for them.


\Once the keys are cut, the process involves walking the floors and trying the keys in the locks. One key in a set will turn the cylinder, thus revealing the change cut in that position. This part of the method can be carried out by a layman since all that is being recorded is cuts that turn the cylinder.

As added value, the keys will reveal when a chamber is empty, master keyed, void of master wafers, loaded with extra master wafers, or defective.

Once all cylinders have been evaluated, a more precise understanding of how the floors are keyed is available.

Instead of just reverse-engineering the KBA to determine new change and master keys, each key that operates a cylinder can be matched to the lock.

The processes are the same in regards to developing a complete KBA. Both processes take about the same time. The guerilla method yields all information and does a more thorough job.

Another advantage is how the method is perceived to the customer. Checking each lock with a system the customer understands is preferable.

Many times locksmiths will turn down requests because of the condition that the existing system be left intact. The customer should be willing to invest the time for the locksmith to properly research the system to make sure that continuance is viable.

Locksmiths can better serve their customers by learning different methods on how to reverse engineer the KBA and recreate missing master key records.


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