| Ornamental Turning Book of Knowledge |
A Geometric Chuck is used for cutting patterns made up of rolling centres. The details are difficult to explain, and are better explained by John Edwards' document.
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 - The Principles and Practice of Ornamental or Complex Turning (1884). There is an article about one in the "English Mechanic and Mirror of Science", Vol VII, No. 171 (03 July 1868). And John Edwards captured this and more in what he calls the "Holtzapffel Volume 6". You can get a copy from the The Society of Ornamental Turners.
Newer Geometric Chuck