Collet Basics

Where does it sit?

A collet (C) is used in a spindle motor (D), to clamp a cutting tool (A) to the end of the spindle taper (E). A nut (B) is used to compress the collet which applies a clamping force to the tool. 

A: Tool

B: Spindle nut

C: Collet

D: Spindle unit

E: Spindle taper

What the collet needs to do

Provide the maximum amount of clamping force

By clamping force, we mean the amount of grip the collet has on the tool. A high clamp force:

• Dampens vibration

• Allows for higher RPMs

• Reduces chatter

• Reduces risk of tool pulling out of the spindle

Provide the minimum run-out

By run-out, we mean the distance the tool mis-aligned from the center or rotation (shown below in red).

A low run-out value means:

• All flutes do an even amount of work

  • Even wear

  • Better tool life

• Better finishes

• Better accuracy

• Reduced wear in the spindle bearings