The small-format interchangeable core (IC) is regarded as the “universal” lock mechanism throughout the commercial door hardware industry. Servicing interchangeable cores require specialized tools to ensure smoother operating locks and keys, than conventional lock cylinders. The core...
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The small-format interchangeable core (IC) is regarded as the “universal” lock mechanism throughout the commercial door hardware industry. Servicing interchangeable cores require specialized tools to ensure smoother operating locks and keys, than conventional lock cylinders. The core tolerances are much tighter. The pin diameter is smaller, .108” diameter versus .115” diameter for conventional lock cylinders. To cut a key requires a 90-degree included angle cutter, and cores are not as forgiving as conventional lock cylinders.
Just some background information: Best developed the A2, A3 and A4 systems to provide expanded keying options when setting up their interchangeable core systems. The A2 system is based on a .0125” increment between the pins lengths. The A3 system is based on a .018” increment. The A4 system is based on a .021” increment.
For this article, unless otherwise specified, I will be discussing interchangeable core products based on the Best A2 system. When discussed, I will list manufacturers alphabetically.
Manufacturers of interchangeable cores include Arrow, Best Access, Best Security, Corbin Russwin, CX-5, DORMA, Falcon Lock, GMS, Ilco, KSP, Medeco, Mul-T-Lock, PDQ, Sargent Lock, Schlage Lock, Ultra Security and Yale Lock.
Some of these manufacturers offer higher security and patented key control. These specialized cores are manufactured to the basic outside dimensions allowing interoperability between manufacturers interchangeable core lock housing products. For example, Medeco has KeyMark Interchangeable Core. CX-5 has the Waved Security Groove. Schlage has the Everest.
Depending upon the manufacturer and the key material, there are three different pin types for interchangeable cores.
- Flat nose, nickel silver material pins designed specifically for Best Interchangeable Cores.
- Nickel silver material with the radius blended into a +/- .015” flat nose for all other interchangeable cores except BEST.
- Brass IC pins with a radiused nose for Interchangeable Cores that will be operated with brass keys.
The pin shapes and composition materials affect the operation and life expectancy of interchangeable cores and the keys. The recommendations are to use brass bottom pins when the cores are operated by brass keys. Use nickel silver bottom pins when using nickel silver keys. This will optimize the life expectancy of the keys and the cores. Top pins, build-up pins and master pins are normally brass.
Pinning kits are available from the core producers and LAB. LAB offers different styles of rekeying kits. Steel, wood and polyethylene cases contain varying quantities of pins. The bottom pins are brass or nickel silver depending upon the kit.
Early Best and Falcon manufactured interchangeable cores used a plate-style spring retainer like most conventional mortise cylinders to retain the springs and pins in each pin chamber. Over time, the design changed to individual pin chamber caps, eventually replacing the plate style spring retainer.
There are two different sizes of pin chamber caps for interchangeable cores. Stamped pin caps are .1185” diameter and machined pin caps are .117 +/- .0005 diameter. Stamped pin caps are manufactured of a softer brass.
Specialized tools are required to service or recombinate the core. There are tools that are single function such as loading, unloading or capping the pin chambers. Unloading tools, commonly known as “Dump” Tools, operate with an ejector pin. These products are designed to remove the pin chamber caps, permitting the springs and pins to be removed. Some have an attachment that captures the content of each pin chamber unloads separately and in order. This permits decoding the pins to determine the operating key depths of cut and the top master key depths of cut, as well as decoding the control key bitting.
Each IC lock manufacturer has its own pinning system. For locksmiths who service many different types of IC systems, it can be difficult to remember which pinning system to use.
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