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.

The key is to fully engage (clip in) the collet inside the nut before you tighten it onto the holder. When properly seated, your collet face should be flush with the face of the nut - almost press fit into the nut. At that point, you're ready to place your tool into the collet and tighten things into the holder.

As the collet is pushed into the pocket by the collet nut, the slots in the collet allow the I.D. bore to collapse and apply clamping pressure to the cutting tool shank. The result is a very strong and rigid clamping force on the cutting tool.