R8 tool holder made in the USA
12 August 2015

Category: tools
12 August 2015,

Collets in the CNC Shop

Collet is a term that gets tossed about freely in metal working and wood working shops. It’s one of those words everybody uses and assumes everybody else knows what it means. Is a chuck a collet or is it something different? And what the heck is a collet wrench?

A collet is a type of chuck. So all collets are chucks, but not all chucks are collets. A collet is nothing more than a tool holding device that works by clamping down. It allows you to strongly clamp a collar around whatever it is that you are trying to hold in your collet.

Common Collets

Mancollet wrench word graphicy types of collets are used in the metalworking industry. The common industry-standard designs are R8 (internally threaded) and 5C (externally threaded). Collets can hold square or round stock. In addition, there are also proprietary designs and emergency collets, made by the machinist.

R8 Collets. The R8 collet design was developed by Bridgeport Machines, Inc., a company that made milling machines and milling centers. They were manufactured under that name from 1938 to 2004, when the company was sold to Hardinge, Inc. R8 was developed to allow rapid tool changes and requires an exact match between collet and tool shank diameter. R8 collets fit into the machine taper itself. R8 collets fit into the machine taper itself.
5C Collets. 5C collets were developed primarily for work holding instead of tool holding. They look like R8 collets, but 5C collets have an external thread at the rear for drawing the collet closed. This way the work piece can pass right through the collet.

Why Collets Wrenches are Important

Enough about collets already, why do you need a collet wrench? Well, when properly tightened, a collet applies enough to securely clamp the workpiece or tool and hold it in place. This is what a collet wrench does. If your collect isn’t tight enough bad things can happen.

  • The tool can chatter and ruin the workpiece (and the tool).
  • If the workpiece isn’t tight enough it won’t be tooled properly (and you can ruin the tool and workpiece)
  • The tool or workpiece can fly, causing a very real danger.

You need a collet wrench to make sure the collect is firmly in place. You need a Sierra American Collet Wrench.

The Right Collet Wrench Makes a Difference

The Sierra American Collet Wrench was designed to insert and remove 5C collets or R8 collets from nose piece of all CNC lathes with ease. It makes you much more efficient because you have simplified the insertion and removal of collets on the spindle.collet wrench


The time spent changing out collets is time the machine is not running and work is not being produced. This downtime is a necessary part of the work process, but you want to minimize it as much as possible to maximize efficiency. The Sierra American collet wrench is the answer.

  • It is designed and manufactured in the USA to make you work easier.
  • It is the only collet wrench with a concave face for perfect alignment, no slipping here.
  • It has a large tapered handle that makes it easy to use
  • It is bright orange so it is easy to see which makes it easy to find.

If your tool supply doesn’t offer Sierra American collet wrenches, ask them to order one for you.
To locate a local dealer call (800) 576-5331, email tools@sierraamerica.com or use our handy Contact Us form today.

One response on “Collet Wrenches Make You a Quick Change Expert

  1. […] you are using an R8 or 5C set-up, having your collets at hand and a good collet wrench can help you become a quick change artist. A good R8 tool holder or collet tray will help you work […]

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