Collet

A collet is a segmented sleeve, band or collar, usually with one radial surface tapered and the other cylindrical, most often made of spring steel with one or more cuts along its length so it can expand and contract. The term commonly refers to a type of chuck that uses a collet to hold a workpiece or a tool such as a drill: an external collet has a cylindrical inner surface and conical outer surface that is squeezed against a matching taper so its inner surface contracts to grip the tool or workpiece securely, while an internal collet instead clamps against the bore of a hollow cylinder as a corresponding taper is forced into its internal taper. As a clamping device a collet can produce high clamping force with accurate alignment, and is used across metalworking, woodturning and other trades wherever a tool or workpiece needs to be held on a precise, repeatable centerline.