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.

Geometric Chuck
Image courtesy of Skinner, Inc.

Additional pictures of this device

Newer Geometric Chuck

5 Stage Geometric Chuck by Plant

Drawing of Plant's 5 Stage Geometric Chuck

Examples of work produced with this device

Examples of this device in use

  • This YouTube video from Chuck Bommarito (aka, outsidescrewball) shows 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 YouTube video shows an Ibbetson Geometric Chuck on Holtzapffel rose engine lathe No. 1636.

Usage Notes

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 a 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.

Notes on making one

A fella named Thomas posted instructions on for 3D printing one. A YouTube video about this in use is noted below.

More Information

Published Articles

  • Designing 'Geo-Flowers' with a Geometric Chuck by Joshua Salesin. The Society of Ornamental Turners Bulletin 144, Spring, 2021, pg. 21
  • Geometric Turning: The Manufacturer and Builder, by (unknown). Ornamental Turners International Newsletter, Volume 20, No. 1 - Spring, 2013, pg. 5
  • Plant's Geometric Chuck, by (unknown). Ornamental Turners International Newsletter, Volume 25, No. 1 - Summer, 2018, pg. 19
  • There is also an article about one in the "English Mechanic and Mirror of Science", Vol VII, No. 171 (03 July 1868).

Books and Papers

  • Specimens in Eccentric Circular Turning with Practical Instructions for Producing Corresponding Pieces in the Art, by John Holt Ibbetson (1884).
  • Index to the Geometric Chuck, by Thomas Bazley. The Bazely book also has some nice pictures showing what can be produced on such an apparatus.
  • Holtzapffel Volume 6, by John Edwards. John captured quite a bit about these devices here. You can get from the The Society of Ornamental Turners
This chuck is so complicated that John Jacob Holtzapffel never got around to putting it into his last published work, Turning and Mechanical Manipulation, vol. 5.

Web Sites

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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.