Disadvantages of collets Collets are limited in the range of workpiece sizes they can accommodate and are ideally suited for repetitive jobs where the clamping requirements don't vary greatly. They are also better suited for clamping tooling with longer shanks and workpieces with consistent diameters.

Diameter range is the most notable difference between collets and chucks. Generally collets are used on smaller work pieces than typical three-jaw chucks. The general range for collets are 1/16in to 2.5in whereas chucks can be used on work pieces that are larger.

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. There are several types of collets that look like ER collets.

ER32 Collet Clamping Range 2mm Super Precision with Runout less than or equal to 0.005mm at 4xD, 33mm Outside Diameter 40mm Long. 0.005mm runout collets should only be used to grip the nominal diameter if used for smaller diameter runout will increase and collet life will be shortened.