Bit (key)

A warded lock type key with its main parts labelled

The bit of a key is the part that actually engages the locking mechanism of a lock. (For example the tumblers in a pin tumbler lock.)

The exact geometry of modern keys is usually described by a code system. This is referred to as the bitting. The bitting instructs a locksmith how to cut a certain key, to replace a lost key or make an additional copy.

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 to settings on specially designed key machines. In many code systems each digit in the bitting corresponds to a certain location on the key blank where a cut or notch is to be made and also indicates the necessary depth of the cut.

Many lock companies use their own proprietary code system. 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. 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. One American manufacturer, Eagle Lock Company, used letters exclusively for bitting codes.

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) (this is also used in Schlage Primus) or to line up an interlocked pin to such a position to where it would allow the plug to rotate (Emhart).

See also

• Keys by code

Locksmithing & Lock picking
Topics	Electric strike Key control Key relevance Lock bumping Lock picking Lockout-tagout Maison key system Rekeying Single-point locking Three-point locking
Components	Bitting Bolt stump Break Interchangeable core Key blank Key code Keyhole Lockset Shear line Split pin
Key types	Berlin key Bump key Change key Master key Skeleton key Smart key Tubular key Transponder key
Mechanical Locks	Bored cylindrical lock Bramah lock Cylinder lock Disc tumbler lock Key retainer Lever tumbler lock (Chubb detector lock) Magnetic-coded lock Magnetic keyed lock Mortise lock Padlock Combination lock Rotary combination lock Time-delay combination locks Pin tumbler lock (snib) Protector lock Relocking device Time lock Tubular pin tumbler lock Warded lock Wafer tumbler lock
Electronic Locks	Electromagnetic lock Electronic lock Electric strike Magnetic-coded lock Keycard lock Electronic/digital-cylinder pin tumbler lock
Specific lock types	Bicycle lock Chamber lock Child safety lock Dead bolt Keycard lock Kensington Security Slot Luggage lock Power door locks The Club TSA lock
Tools	Lockpick Slim Jim Snap gun Tubular lock pick
Related	Bolt cutter Door chain Exit control lock Famous locksmiths Interlock (engineering) Keychain Key (engineering) Lock manufacturers Lock puzzle Lock snapping Locksport Two-man rule
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