Editing Collet (section)

{{Short description|Type of chuck}}
{{other uses|Collet (disambiguation)}}
{{More citations needed|date=November 2009}}
[[File:External_thread_pull_collet_action.gif|thumb|right|A W-type external-thread collet (red) being pulled into its spindle seat (green) with a drawbar (blue), clamping, rotating and then releasing a shaft.]]

A '''collet''' {{IPAc-en|ˈ|k|ɒ|l|ᵻ|t}} is a segmented sleeve, band or ''collar''.<ref>[https://www.collinsdictionary.com/dictionary/english/collet Collins Dictionary], accessed 1 June 2020.</ref><ref>[https://www.merriam-webster.com/dictionary/collet Merriam-Webster Dictionary], accessed 1 June 2020.</ref>  One of the two radial surfaces of a collet is usually tapered (i.e a truncated cone) and the other is cylindrical.  The term ''collet'' commonly refers to a type of [[chuck (engineering)|chuck]] that uses collets to hold either a [[workpiece]] or a tool (such as a drill), but collets have other mechanical applications.

An external collet is a sleeve with a [[cylinder (geometry)|cylindrical]] inner surface and a [[cone (geometry)|conical]] outer surface. The collet can be squeezed against a matching taper such that its inner surface contracts to a slightly smaller diameter, squeezing the tool or workpiece to hold it securely. Most often the collet is made of [[spring steel]], with one or more [[wikt:kerf|kerf]] cuts along its length to allow it to expand and contract.  This type of collet holds the external surface of the tool or workpiece being clamped.  This is the most usual type of collet chuck. An external collet clamps against the internal surface or bore of a hollow cylinder.  The collet's taper is internal and the collet expands when a corresponding taper is drawn or forced into the collet's internal taper.

As a clamping device, collets are capable of producing a high [[static friction|clamping force]] and accurate alignment. While the clamping surface of a collet is normally cylindrical, it can be made to accept any defined shape.