Compound four-part geometric chuck, by Holtzapffel and Co. with change wheels and accessories, in two mahogany cases; also special stand for operating, with fifteen designs drawn by the pen
Compound four-part geometric chuck by Holtzapffel and Co, with change wheels and accessories. The Geometric Chuck was invented by J H Ibbetson in the early 19th century for the purpose of producing intricate patterns. Generally used on lathes for ornamental turning, this is the only known surviving example of a four stage chuck. The movement of each stage is defined both by its speed of rotation and by the amount the centre is offset compared with the stage below. These two factors give each stage an epicycloidal motion which is superimposed upon the movement imparted from lower stages.