The easiest way to determine what type of collet your machine has is to measure the length and diameter of the collet. All collets have a distinctive length and diameter.

Collet: Definition Collets are used to hold a tool in a central position as it rotates. As the tool is inserted into the collet, the device expands and provides uniform pressure that holds the tool in place. However, if the collet stretches too far, it cannot secure the instrument properly and may lose shape.

What type of collets are there? There are two types of collets, workholding and toolholding.

ER collets have a wide clamping range and high accuracy. While they are designed for tool holding, they work great for work holding in small lathes. With a full set of ER collets you can hold any diameter that is in the clamping range of the set.