Measuring Guide

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.  Use the chart below to determine the correct collet series for your machine. If you need advice, give us a call or send us an email, and one of our specialists will help you get the best performance out of your tooling. Ensure that you have the correct size for your CNC and the router bit being used. Damaged or worn collets, as well as improperly sized collets, lead to poor tool performance and premature wear.
Collet Series Length Diameter
ER11 18 mm (.708″) 11.5 mm (.45″)
ER16 27.5 mm (1.08″) 17 mm (.67″)
ER20 31.5 mm (1.24″) 21 mm (.83″)
ER25 34 mm (1.34″) 26 mm (1.02″)
ER32 40 mm (1.57″) 33 mm (1.3″)
ER40 46 mm (1.81″) 41 mm (1.61″)
SYOZ 20 34 mm (1.34″) 20 mm (0.78″)
SYOZ 25 52 mm (2.06″) 35 mm (1.38″)
Using the right size collet for your tool shank diameter is crucial. First, make sure that you look at the correct sort of collet to fit your machine’s spindle or tool holder. A common error is the attempt to fit a shank tool that’s too large into a smaller collet. It’ll go in, and you’ll be able to tighten it, but the collet will be stressed. This can cause vibration and imbalance causing the tool to leave a poor surface finish. It is also potentially dangerous to the operator should the tool break or be thrown from the collet.