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Making dies

To begin with, an artist prepares a low-relief plaster model (1) of the chosen design. The plaster model is placed on a scanner where a ruby-tipped probe slowly traces over the surface (2), recording the details of the design as a digital file on a computer. Modifications can then be made to the design on-screen using a sophisticated Computer-Aided Design package. When the design has been finalised, the digital file is translated into a cutting programme, a series of XYZ co-ordinates instructing a computer-controlled engraving machine how to cut the design into a soft piece of steel at coin size (3). The design is cut in two stages, a rough cutter removing the bulk of the metal and a fine cutter adding the detail.

Known as a reduction punch, the steel tool cut on the engraving machine bears the features of the design in relief as on a coin. After it has been worked on by hand, to remove defects and strengthen features of the design, the reduction punch is hardened by heat treating. It is then sunk into another soft piece of steel to produce a tool, known as a matrix, on which the features of the design are incuse. More handwork follows and then the matrix is hardened and sunk into a soft piece of steel to produce a working punch. Yet more handwork, then the working punch is hardened and sinks the dies which are used in the coining presses. Even at this late stage, still more handwork is required to sharpen the design details on the dies (4, 5).

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