FILENAMES: edm1.jpg edm2.jpg DESCRIPTION: These are pictures of a shop built electric discharge machining setup. Posted by Dan Mauch . Dan provided the following description: ================================================================= Here is a great source of knowledge and plans for building a computer controlled Sinker-Electrical Discharge Machine (EDM). From what I can see it is better than the one in HSM. Here is the description. Other information about CNC, tachometers and more is on my web site at www.seanet.com/~dmauch Here are some narratives from the plans for building a really nice CNC EDM. Spark Erosion, or more commonly known as Electrical Discharge Machining (EDM), is a special type of machining technique. It's essentially based on repetitive electrical spark discharges, which lead to localized erosion of a work piece. The tool, which delivers the discharges, erodes into the work piece. It sinks itself in, and its reciprocal profile is thereby formed into the material. Hence, the term Sink EDM. EDM has gone through an extensive amount of development. It has proved to be a very useful machining technique and its presence in the modern workshop has become more or less mandatory. The EDM process is not a high speed machining process. Yet it carries other attributes like high precision and the ability to work materials that are too hard to form using conventional mechanical techniques. It allows the machinist to create highly complex intricate precision parts, which could sometimes not be produced efficient-y by other means or not all. This manual describes the building of a Desk Top Sized Sink EDM unit. It's a simplified version of its SEDM industrial counterpart. The unit is a single axis 300 watt computer controlled system, which uses the PC's parallel port as the communications channel. It can cut through just about any electrically conductive material irrespective of material hardness. Its use may be for simply removing broken taps out of a work piece but it can also create small profiles like square shaped holes or even more intricate designs. The unit has been designed in such a way that lathe/mill work is not required. Anybody with basic home shop machinery and tools, and naturally some electrical/mechanical know-how, can create their own home made Sink EDM setup. Provided that certain materials can be purchased pre-sawed, to the required dimensions, the main manufacturing task is drilling holes. A good drill press is the only real machine needed to complete the unit. Software code is also included in this publication. It's "test" software or testware. This will control the unit and allow it to perform all the necessary basic functions. Explanations are provided, which permit a basic insight into the workings of computer controlled machinery. The chosen design concept is based on various criteria. Every aspect possible from the design to the assembly has been stepped down to the most basic and cost effective level. This, while allowing the unit to still incorporate the precision and durability to create a well performing and useful system. Naturally some builders may, for their own reasons, choose other ways to build the unit or make modifications to the design and workings for their own purpose. Yet the unit described here has proved its design in practice. Hope-fully builders will construct it first before attempting any major modifications of their own. Every effort has been taken to choose a design plan that incorporates common and available components. However this may not be the case everywhere. Modifications may therefore still be necessary. Use the design (then) as a guideline. Yet try and keep the modifications as limited as possible. The explanations of the operation of the process and the unit will hopefully allow the builder to understand what is and what is not possible. The building of the unit requires some skill. Yet those who are acquainted with basic machining should have no problem (here.) Naturally, time, attention and patience to manufacture and assemble the unit are required. An important aspect, that demands attention, is safety. EDMing can be very dangerous and even fatal when used incorrectly. Liquids, electricity, flammable substances and sparking can be a lethal combination. Be alert! CNC machining is becoming more and more wide spread for the home shop as information and components become more accessible and less expensive. This allows the home machinist to adapt new technology into his or her workshop. More easily can ideas now be translated into tangible, functional products or even artwork. Hence, the recent introduction of PC controlled EDM into the home shop is not that surprising. Yet there are several other machining processes, some known and some less known, that the home machinist can incorporate. Hopefully this publication will serve as the stepping stone as the first of many more Proved by Prac-tice Publications. Your purchase of this manual, and the building of this unit, will invite the incen-tive to carry on and provide more publications. Publications that regard relatively inexpensive and easy to build yet versatile machining units for your home shop.