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. www.skinnerinc.com

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.

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.

• Geometric Turning: The Manufacturer and Builder, by (unknown).
  OTI Newsletter, Volume 20, No. 1 - Spring, 2013, pg. 5


• Plant's Geometric Chuck, by (unknown).
  OTI 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).

• 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.

• The details are difficult for me to explain, and are far better explained by John Edwards' document. John captured this and more in what he calls the "Holtzapffel Volume 6", which you can get from the The Society of Ornamental Turners.