Geometric Chuck


2 Stage Geometric Chuck by Ibbetson

A Geometric Chuck (sometimes called an Epicycloidal Chuck) is used for cutting patterns made up of rolling centres.

Just getting started? : You can definitely delay getting one of these.

Geometric Chuck
Image courtesy of Skinner, Inc.

Additional pictures of this device

Newer Geometric Chuck

5 Stage Geometric Chuck by Plant

Examples of this device in use

Leinhard Rose Geometric Chuck

This is a YouTube video from Chuck Bommarito (aka, outsidescrewball) showing a Leinhard Rose Geometric Chuck in use. The video is a bit long, but does show the chuck well, as well as a piece made on it.

This video shows an Ibbetson Geometric Chuck on a Holtzapffel rose engine lathe.

How it works

Basically, it is achieved by rolling one object around another, forming a composite of two perfectly circular motions. The geometric mathematics behind this chuck's movement are explained by Dr. Frank Farris in his 1996 paper, "Wheels on Wheels on Wheels-Surprising Symmetry". There is also a nice article on this at Wolfram MathWorld.

Frank Dorion gave this lecture on the design and functions of a geometric chuck. He also built an oversized wooden model of one, helping to explain it's function. This is one of the best overviews presented to date.

More Information

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Disclaimer : eMail comments to me at OTBookOfKnowledge @ The process of woodturning involves the use of tools, machinery and materials which could cause injury or be a health hazard unless proper precautions are taken, including the wearing of appropriate protective equipment.