Master keying- a guide for commercial security systems

Posted by | Locksmithing, Security Engineering | 0 |

A Guide to Master Keying

What is it?

Master keying is a system for keying in which more than one “master key” has the power to operate one lock or all the other locks. It is used to restrict or allow access to different areas/offices in a facility based on a user’s access level. Essentially, the facilities manager can hold the master key, which gives him access to all areas, but another employee, could only have access to one location in the building.

Master Keying Schemes


Construction keying

A movable component is added to the traditional locking components. During “construction”, users can use keys that raise these components to the shear line. When the lock is ready to be used by the real owners, the components are removed so that the old keys no longer work. Construction keying is mainly used with pin-tumbler locks, though break-away components can also be used with other designs.

Interchangeable Cores

Interchangeable cores allow user-rekeying by physically removing the cylinder and replacing it with a different cylinder. Interchangeable core locks usually feature two shear lines which operate independently from each other. One shear line engages the bolt mechanism, and the other shear line operates the core removal mechanism.

Maison Keying

Maison keying is a system that permits a lock to be opened with a large number of unique keys. Maison keying is very common in older schools and apartment building common areas. However, security may be compromised to ensure a larger number of users can all access shared resources. Maison keying is performed by removing components or extreme master keying levels, both of which greatly reduce the security of the lock and keying systems.

Master Rings

In a master ring, a secondary plug is located around the primary plug. The user keys operate the traditional shear line, but the master keys can operate the second or “master” shear line to open the lock. The function of master rings is similar to interchangeable cores, except the master ring doesn’t have a cylinder which can be removed.

Partial Position Progression

Partial position progression method of master keying in which certain positions are moveable while other positions are held constant. With split-pin master keying, this means there are certain cuts on the keys which are the same on every key in the system, and there are certain chambers in the locks which never have master pins in them. This method is very useful for small systems.

Rotating Constant Progression System

A form of master keying in which some positions are moveable and at least one position is held constant but the location of the constant is not fixed. This method is very useful for producing two-level systems with large numbers of change keys. Surprisingly, it produces more available change keys than total position progression does, in most cases. As with partial position progression, every key has at least one cut in common with the top master key and most locks have at least one chamber with no master pins in it.

Sectional/Multiplex Keyways

A master keying scheme where the keyway profile of a key is used to restrict physical entry of the key to one or more locks. Keys with low levels of access will have key profiles that cannot be inserted into higher level locks. Keys with high levels of access will have most of their warding removed, allowing them to be used in all or most of the locks in the system. This scheme is commonly used in addition to traditional master keying schemes, but can also used alone. In warded locks, sectional keyways may be the only type of master keying available.

Total Position Progression

A method of master keying in which every position is progressed. With split-pin master keying, this means the lowest level change keys share no cuts in common with the top master key and most locks have a master pin in every chamber. This method is useful for producing systems with many levels of keying. Some consider it to be the default method to be used in every situation but it creates excessive incidental keys, which is contrary to ANSI standards.

How can I set up a master key system?

Here at Accurate, we can easily custom design a master key system to suit your needs. Simply come visit us or call in to set up a personal consultation.