Bitting

A bitting is the part of the key that actually engages the tumblers to activate the lock. Bittings are often represented as a code which instructs how a key is to be cut by a locksmith. The bitting is usually a series of integers (e.g. 372164) that is usually translated from a key code chart or from a bitting code list and the use of specially designed key machines. One American manufacturer, Eagle Lock Company, used letters exclusively for bitting codes.

Each digit in the bitting corresponds to a different cut or notch on the key and represents the depth at which the key must be cut. Each number in a bitting represents not only the depth of which the key blank is to be cut, but also the location of the cut on the key blank. Depending on the maker, the bitting sequence can be from bow-to-tip (the bow being the larger, handle portion of the key), or can be from tip-to-bow as is in the case of Best Locking Systems and Assa. A smaller number is typically a shallower cut on the key, but not always. Assa bitting codes are reversed, where the higher the digit, the shallower the cut.

Locksmiths can cut to the code given when supplying a lost key or making a new restricted key copy. See also:Keys by code

Angularly bitted

This is a type of key where the individual cuts are designed to engage chisel-pointed pins in high-security locking systems manufactured by Medeco and Emhart. These angled cuts are designed to lift each tumbler to a predetermined height to the shear line and to rotate them to a specific angle to engage a sidebar mechanism (Medeco) or to line up an interlocked pin to such a position to where it would allow the plug to rotate (Emhart).