Date: April 23, 2021
Preparation of the sphere. I am using Robert Bosco’s method. He created a very nice site with a lot of fabulous information.
http://robert.bosco.pagesperso-orange.fr/modeleen.htm
Tracing of the primary and secondary openings.
I used the Excel spreadsheet of Claude Lethiecq that Jean Claude Charpignon sent me to help me with the tracing of the various openings.
The most importance, as Paul Texier and Jean Claude Charpignon will tell you, is that the sphere needs to be perfect “Diameter +0/-0.1mm”.
Mine was a “patatoïde”. I had a template for a 65 mm diameter as recommended by Robert Bosco, but I forgot to use it … I was so excited to finish my first sphere. I had a hard time to recover after cutting the tendons. I switched to the “Plumier’s method” from his publication “L’Art de Tourner en Perfection” printed on September 7, 1701.
I used Jean Claude Charpignon’s tools:
The making …
A “Boule de Canton”: a sphere of 65 mm with 6 spheres inside in maple.
The mother sphere has 3 mm wall, the other 5 spheres have 2 mm wall and the central sphere has a diameter of 15 mm.
I decided to do a finial and a spiral support. The idea comes from “The Manuel du Tourneur” by L. E. Bergeron, 1816, planche 12, fig. 33. The disks of the spiral are 1 cm diameter and 2.5 mm thick. The diameter of the spiral is 3 cm with a full turn in the middle and reverse turn at each extremity to come back to the center.
Une Boule de Canton : La sphère extérieure fait 65 cm de diamètre et 3 mm d’épaisseur, les 5 sphères à l’intérieur font 2 mm d’épaisseur et la 7ieme au centre fait 15 mm de diamètre. J’ai décidé de faire un fleuron et un support excentrique de disques de 1 cm de diamètre et 2.5 mm d’épaisseur avec une base en sycomore. La spirale fait 3 cm de diamètre avec un tour complète au milieu et à chaque extrémité en sens inverse pour retourner au centre.
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