Key duplication

Key duplication refers to the process of creating a key based on an existing key. Key cutting is the primary method of key duplication: a flat key is fitted into a vise in a machine, with a blank attached to a parallel vise, and the original key is moved along a guide, while the blank is moved against a blade, which cuts it. After cutting, the new key is deburred: scrubbed with a wire brush, either built into the machine, or in a bench grinder, to remove burrs which, were they not removed, would be dangerously sharp and, further, foul locks.

Different key cutting machines are more or less automated, using different milling or grinding equipment, and follow the design of early 20th century key duplicators.

Key duplication is available in many retail hardware stores and as a service of the specialized locksmith, though the correct key blank may not be available. More recently, online services for duplicating keys have become available.

In the UK, the majority of the mobile locksmiths will have a dual key cutting machine on their van. The key duplication machine will be able to cut both cylinder and mortise keys, as these are the most popular types of keys in circulation. However, very few will carry a laser key cutting machine, which is sometimes needed to cut high security keys.

Certain keys are designed to be difficult to copy, for key control, such as Medeco; while others are simply stamped "Do Not Duplicate" to advise that key control is requested, but in the US, this disclaimer has no legal weight.