[Ben Krasnow] Drills Really Small Holes with Electricity

Drilling holes is easy; humans have been doing it in one form or another for almost 40,000 years. Drilling really tiny holes in hard materials is more challenging, but still doable. Drilling deep, straight holes in hard materials is another thing altogether.

Luckily, these days we have electric discharge machining (EDM), a technique that opens up all kinds of possibilities. And just as luckily, [Ben Krasnow] got his hands on some EDM gear to try out, with fascinating results. As [Ben] explains, at its heart EDM is just the use of a small arc to ablate metal from a surface. The arc is precisely controlled, both its frequency via an arc controller, and its location using CNC motion control. The arc controller has always been the sticking point for home EDM, but the one [Ben] tried out, a BaxEDM BX17, is squarely aimed at the small shop market. The whole test platform that [Ben] built has a decidedly home-brew look to it, with a CNC gantry rigged up to a water tank, an EDM drill head spinning the drill rods slowly, and an airless paint gun providing high-pressure process fluid. The video below shows that it works remarkably well nonetheless.

While we’re certainly keen to see [Ben]’s promised videos on EDM milling and cutting, we doubt we’ll line up to shell out €2,950 for the arc controller he used. If you have more courage than money, this mains-powered EDM might be a better fit.

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EDM for the Cheap and Adventurous

Laser cutters, waterjets, plasma cutters, CNC routers – most hackerspaces and even many dedicated home-gamers seem to have some kind of fancy tool for cutting sheet goods into intricate shapes. But with no access to a CNC machine and a need to cut a complex shape from sheet metal, [AlchemistDagger] cooked up this bare-bones and somewhat dangerous EDM rig to get the job done.

Electric discharge machining has been around for decades and is used a lot for harder metals like titanium and tool steel. The process makes sense to anyone who has seen contacts pitted and corroded by repeated arcing – an electric arc is used to remove metal from the workpiece, with a dielectric fluid used to cool the workpiece and flush away debris. For [AlchemistDagger]’s purposes, a lot of the complicated refinements, like high-frequency power supplies and precise tool positioning, were ignored. He built a simple linear slide to manually control the tool position, and the power supply was just a bridge rectifier connected to the 120-volt mains with some filter capacitors and a big light bulb as a ballast resistor. While the video below shows electrical conduit being notched, [AlchemistDagger] also made a brass cookie-cutter style tool to cut the Instructables logo from steel.

Obviously, mixing water and electricity is a recipe for disaster is you’re not careful, but this low-end EDM technique is a good one to file away for a rainy day. And if you’re looking for a little more sophistication in your homebrew EDM rig, we’ve got you covered there too. Continue reading “EDM for the Cheap and Adventurous”