Rekeying a conventional pin tumbler lock typically
involves removing the entire lockset from the door, or at the very least
removing the outside handle if it is a keyed lever. This can become a time consuming experience due to any
number of reasons ranging from stuck bolts to removing multiple coats of paint
that have sealed the lock to the door.
Because of this, many businesses, universities and other large
institutions use locks that accept what are known as Interchangeable Cores (Abbreviated I/C).
The
first type of I/C was the Small Format
Interchangeable Core (SFIC), invented by Frank Ellison Best around
1920. Shortly after, Best Lock
Corporation was established to manufacture SFICs. Because the patent on SFICs has now expired, other
manufacturers such as Arrow and Falcon also produce them. SFICs are not brand-exclusive, meaning
that an Arrow can be used to replace a Best and vice versa. Large
Format Interchangeable Cores (LFICs) however, are brand exclusive.
 |
| Older Best SFIC with its operating key in use |
What’s
unique about I/C locks is that they do not need to be rekeyed on site. Instead, they are removed from the lock's housing
using a special key, known as a control
key. Rotating this key 15
degrees clockwise allows the user to remove the entire core through the front
of the lock. A new core is
inserted into the front of the lock using either the same or a different
control key. The new core has been
rekeyed beforehand to accept a different operating
key. An operating key only
locks and unlocks the lock—it cannot be used to remove the core. The old core can be taken to a
locksmith (or shipped back to the supplier) to be rekeyed for future use.
 |
| Best SFIC, partially removed from a mortise cylinder housing. Notice the slight angle of the control key |
Because
SFICs can be rekeyed without the need to summon a locksmith to the location of
the lock, they are the preferred choice for many large businesses and
universities. For this reason,
SFICs are typically shipped to a site and not serviced by a local
locksmith. The exception to this
practice would be universities and large hospitals, which typically employ an
in-house locksmith to pin their SFICs.
Unfortunately, if the control key is lost or misplaced, the core will usually
have to be destructively removed. It
is very difficult to pick an SFIC to the control position because one will most
likely pick it to the operating position instead, thwarting attempts to
nondestructively remove the core.
Wooters Lock Company, LLC uses a minimally destructive method for SFIC
removal, which allows the core to be removed while still keeping the pins intact. By keeping the pins intact, they can
later be removed from the core and decoded, allowing for a replacement control
key to be originated by code.
Generally most SFICs in a system use the same control key. From there, other cores in the system
could then be removed without the need for any further drilling.
 |
| My personal collection of Best SFICs |
SFICs
are a good investment for users expecting high rates of turnover. Landlords for example, may benefit from
having these on their properties, as they would not have to call a locksmith
out each time the locks on a property need to be changed. This would save them any trip charges
or after-hours fees depending on the urgency of the situation. Homeowners however may find these to be
impractical, as the upfront costs are typically higher than having their
existing door hardware rekeyed just once.
