Large Format Interchangeable Cores

Over the years, interchangeable cores have become very popular. The nomadic nature of today's institutions and corporations require flexible keying systems that can be easily moved and re-configured. As large and small facilities change ownership or move to another state, interchangeable cores facilitate the need.

The interchangeable core was originated by Frank Ellison Best in 1912, and patented in 1921. The "figure-eight" format was first produced in 1925 and was slow to be accepted as a hardware standard. The main obstacle relating to product acceptance was that other brands like Corbin, Russwin, Sargent, Schlage and Yale were already established lock companies of choice and offered sufficient keying systems for the times. Additionally, the recombination of cores was perceived as unnecessarily complicated.

Best Lock Company was successful in overcoming these obstacles by working closely with the customer and the customer's administrative designee and evolving the product into a seven-pin configuration that offered four times the key yield as other standard six-pin key systems.

As acceptability grew, existing lock companies succumbed to customer demand by developing their own proprietary interchangeable cores. Customers could then enjoy interchangeability while maintaining their existing keying systems.

Many lock companies offer two types, their own "large-format" proprietary interchangeable cores that work with their established keying systems, and a "small-format" that accommodates "figure-eight" (Best/Falcon) interchangeable cores.

ARE THEY RECORES OR INTERCHANGEABLE CORES?

In 1971, the Emhart Company developed removable cores for its Corbin and Russwin lock lines. To distinguish their cores from Best/Falcon cores, the company coined the cores as "recores." Although sales representatives insisted on using the term, it didn't stick, and today they are referred to as the more typical term "interchangeable cores."

The cores share the same shape as Best/Falcon cores, but are significantly larger. Like Best/Falcon cores, they are held into the sleeve by a control lug on the left -side of the core, but are unlike as dual shearlines appear in the middle chambers only.

The Corbin Russwin "recores" have no control shearline in the first and last chambers. Both control and operating shearlines are implemented in the center chambers. These center chambers use plus, zero, and minus build-up pins.

When a control cut is deeper than an operating cut, a "plus" build-up pin results. Consider the following where the control cut is 6, the change cut is 2, and the master cut is 4. The control pin equals the control cut (6). The bottom pin and master pin would equal 4. Subtract the total of the bottom and master pins (4) from the control pin (6) to get the build-up pin (+2).

When a control cut is the same as the plug total, the build-up pin will be zero. Consider the following where the control cut is 4, the change cut is 2, and the master cut is 4. The control pin equals 4 (the control cut). The bottom and master pin would equal 4. Subtract the total of the bottom and the master pins (4) from the control pin (4) to get a build-up pin (0).

The computation works the same when the control cut is shallower than the deepest operating cut. Consider the control cut is 2, the change cut is 2, and the master cut is 4. Subtract the control pin (which is equal to the control cut) 2, from the total of the bottom and master pins (which is 4), you will get the build-up pin -2.

The order of the stack is the bottom pin, master pin, build-up pin, and last the control pin.

In the first and last chambers, calculate the bottom and master pin conventionally, and the last pin will always be a driver equal to .247"

These Corbin Russwin "recores" are offered either in five- or six-pin configurations, in System 70 keyway groups. In Corbin, the keyway groups are X and Z. In Russwin, the keyway groups are K and N.

MEDECO® INTERCHANGEABLE CORES