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Turning Off.  Trimming on a lathe. This is necessary for large round medals struck from open face dies. After the medals are fully struck, they are placed in a lathe, being held secure between a form mold and a wood plug on the tailstock of the lathe, the FLASH or excess material is then cut off with the tool bit. If this edge trimming is not smooth and minute ridges are visible it is said the tool marks show (they even have a name: annular rings).

Trimming in this manner can only be employed for large round medals – small round medals or irregularly shaped medallic items must be trimmed by specially made cutters or by hand jigsawing. Creating special edges can be performed on the lathe, as concave or contorniate edges – with indentations – or rounded edges by cutting off the corner (the rim/edge juncture) or by creating beveled or double bevel edges.

Any ridges or tool marks may be removed, obviously, by polishing the edges.

(However, leaving the tool marks unpolished is an advantage for large medals, in that they provide somewhat of a grip for fingers to hold only, and as such may be beneficial.) Such a ridged edge is in contrast with a smooth edge from medals struck in collars (as was the practice of the United States Mint in the 19th and early 20th centuries).  See trimming.

Turning on a lathe as a machine shop practice has other uses in the preparation of dies and diesinking. Coining dies must be turned to form the exact diameter and profile to fit the coining press they are intended to be used with; some even require tapered shanks, some require close tolerance on the neck to fit within the collar. While these are turned on a lathe, they need to be cut to precise measurements, often to within ten thousandths of an inch. This work is done as tool and diework.

This two-part medal, the first in America, was created by sculptor/medallist Frank Eliscu. Inspired by a film showing Kauko Rasanen’s Jonah in the Whale, he chose the theme of Pegasus, symbol of an artist’s Muse or Inspiration. Note the two interfaces surfaces are concurrent; the relief side fits exactly within its incuse mate.

 

Inspiration Medal Serial Number

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators

COMPILED AND WRITTEN BY D. WAYNE JOHNSON

Roger W. Burdette, Editor