I have been using the blanking die process, also known as ‘Pancake Dies’ since 2002 when Lee Marshall of Bonneydoon Engineering - and now Knew Concepts – fame, visited Australia to demonstrate his jewelers scale Hydraulic press. As outlined in Susan Kingsley’s book ‘Hydraulic Die Forming for Jewelers & Metalsmiths’, the design of the pancake die with its integral hinge ensures alignment of the punch with the die and allows 2D shapes to be blanked out using a hydraulic press or a fly press.
Conventionally the pancake die is made by hand. This is done by sawing the shape to be blanked into a piece of high carbon steel, in its annealed state, using an angled bench pin, either freehand or with a specially adapted saw frame. Lee Marshall has recently re-designed his die-sawing saw frame, available through Knewconcepts. This new design is an excellent tool for pancake die making.
However, while this way of making pancake dies is perfectly suited to the scale of the studio jewelers’ workshop, I have become interested in investigating the potential for taking the production of pancake dies further. With this in mind I have designed a die to be made using the Electrical Discharge Machining (EDM) process, sometimes referred to as spark machining or spark eroding, and in this case using wire electrical discharge machining (WEDM), or wire-cut EDM, where a thin single-strand metal wire is fed through the work.
Wire-cut EDM has several advantages for pancake die production. Firstly the wire cutting is guided by CAD/CAM software allowing for accuracy and detail not possible by hand. Secondly the wire-cut EDM process has no cutting forces, it’s the spark that’s doing the ‘work’ so to speak, and so the material to be cut can be heat treated prior to cutting, which means that there is little possibility for the material to distort in the way that happens during heat treatment. The downside for the studio jeweler is the cost, finding a toolmaker who can do this for them and that the studio jeweler will need some computer skills (or help from somebody who has) in order to convert idea into a suitable file for wire-cutting.
The image above shows the wire-cut EDM tool, the part cut out and the left over material. Not to be confused with wire-cut EDM is the more accessible alternative for the studio jeweler - Lee Marshall’s Knew Concepts Precision Saw Guide 2 available at http://www.knewconcepts.com/. See the link in the sidebar.
