Draft
Draft. The angle or taper of relief on a model, pattern, mold or die, and, of course, on the piece cast or struck from that original. The bevel at the sides of relief allows a die to withdraw from a diestruck piece; or a cast piece to be released from a mold. A minimum of 5° draft is required for all diestruck pieces (however dies cut on a die-engraving pantograph can only be made with no less than 15° draft). No design relief of less than 5° – and, obviously, no undercuts – can be permitted on a model or pattern from which a die is made. Such an undercut, called reverse draft or backdraft, would first be filled in before such a model could be prepared for any die making. Nearly perpendicular relief, or too steep-pitched relief, would freeze the struck piece on a die and it could not be ejected. Thus any such small degree of draft is impossible to reproduce in diestruck work. See taper; undercut, undercutting.
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