A key-cutting machine generally uses some type of grip to secure the key to be copied and a guide that traces the original, and the machine indicates where the blank should be cut to create a duplicate. The earliest manually operated machines required a great deal of skill to operate successfully and were found exclusively in locksmith shops. The machines became somewhat automated to the extent that personnel in hardware and home supply stores could be trained to operate them.
These semi-automatic machines consist of two parallel vice grips mounted on a sliding arm that is kept pressed against the body of the machine by a tension spring. The operator secures the key to be copied in a grip facing the stationary guide and secures the blank in the grip facing a rotating blade. Once the machine starts, a motor slides the arm holding the two grips from left to right while keeping the guide pressed against the original where it has been cut. This motion presses the blank into the spinning blade at the exact same points to create a duplicate. Errors can occur if the operator fails to properly align the key and the blank in the vice grips, which produces a copy with incorrectly placed cuts, or if he chooses the wrong blank to create the duplicate.
Newer machines use lasers to make more precise cuts and etch the duplicates with dimples that traditional blades cannot reproduce. The latest key-cutting machines resemble vending machines. The customer simply inserts the key to be duplicated into a slot, makes selections on a touchscreen, and receives a copy within seconds of paying the applicable fee. Certain types of keys, such as skeleton keys and those with tubular bodies, still require specialized machinery and expertise, as of 2015.