Exploring A New Frontier: Desktop EDM Is Coming

To say that desktop 3D printing had a transformative effect on our community would be something of an understatement. In just a decade or so, we went from creaky printers that could barely extrude a proper cube to reliable workhorses that don’t cost much more than a decent cordless drill. It’s gotten to the point that it’s almost surprising to see a project grace these pages that doesn’t include 3D printed components in some capacity.

Cooper Zurad

There’s just one problem — everything that comes out of them is plastic. Oh sure, some plastics are stronger than others…but they’re still plastic. Fine for plenty of tasks, but certainly not all. The true revolution for makers and hackers would be a machine that’s as small, convenient, and as easy to use as a desktop 3D printer, but capable of producing metal parts.

If Cooper Zurad has his way such a dream machine might be landing on workbenches in as little as a month, thanks in part to the fact that its built upon the bones of a desktop 3D printer. His open source Powercore device allows nearly any 3D printer to smoothly cut through solid metal using a technique known as electrical discharge machining (EDM). So who better to helm this week’s Desktop EDM Hack Chat?

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Learn How Impossibly Close-fitting Parts Are Actually Made

Most of us have seen those demonstrations of metal parts that mate together so finely that, once together, they have no visible seam at all. But how, exactly, is this done? [Steve Mould] has a video that shows and explains all, and we’ve never seen the process explained quite like he does.

The secret ingredient is wire EDM, or Electrical Discharge Machining, but that’s only one part of the whole. Wire EDM works a bit like a hot-wire cutter slicing through foam, but all by itself that’s not enough to produce those impossibly close-fitting parts we love to see.

EDM is capable of astounding precision in part because — unlike a cutting tool — nothing physically contacts the material. Also, there isn’t a lot of friction and heat causing small distortions of the material during the machining process. EDM is as a result capable of fantastically-precise cuts, but not invisible ones.

It’s pretty neat to see a water jet used to thread the fine wire through the workpiece.

In all good manufacturing, the capabilities (and limitations) of the tool are taken into account, and this is also true for making those close-fitting pieces. The hole and plug are actually made in two separate stages.

The hole is cut separately from the plug, and because EDM is capable of such finesse, the cuts can be made in such a way that they complement one another with near-perfection. After that, grinding and polishing takes care of the surface finish. The result is the fantastically-smooth and apparently seamless fitment we like so much.

The video is embedded below, and there are some great details about EDM and how it actually works in there. For example, we see how a wire EDM machine can use a jet of water to help thread the wire through a hole in the part to start a job, and we learn that the wire is constantly moving during the process.

As cool as wire EDM is, it is not magic and we’ve seen some pretty remarkable efforts at bringing the technology into the home workshop.
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Hackathon Wire EDM Build Really Works

If you’ve ever short-circuited a car battery, you’ve seen the pitting and damage a few sparks can cause. Smart minds realised that controlled sparks could erode metal very accurately, in a process now known as electrical discharge machining. [Tanner Beard] decided to build just such a machine for a hackathon, and it works a treat.

[Tanner]’s video explains the benefits of EDM well. Spark-based machining doesn’t care about the hardness of the given material, making it ideal for working with very tough steels, for example. It’s also non-contact, so the motion platform doesn’t have to be built to resist huge forces.

The build was done with a low budget of just $300, and uses some smart shortcuts. Instead of an expensive mains-powered DC power supply to generate the discharge, [Tanner] just uses a powerful lithium-polymer battery with his own MOSFET board to deliver the high current needed. A nifty combination of a stepper motor and O-drive motor setup feed the discharge wire at a constant rate during the machining.

Overall, it’s a neat build that shows wire EDM doesn’t have to break the bank. We’ve seen other similar builds before, too. Video after the break.

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Cut Just About Anything With This Combination Lathe And Wire EDM

They say that if you have a lathe, you have every other machine tool too. To some degree, that’s true — you can make almost anything on a lathe, including another lathe, and even parts best made on other machine tools can usually be made on a lathe in a pinch. But after seeing this lathe attachment for a DIY electric discharge machining tool, we might be inclined to see the EDM as the one machine tool to rule them all.

Now, we’ll admit that the job [BAXEDM] built this tool for might be a little contrived. He wanted to make some custom hex inserts for his Swiss Army knife, which seem like they’d have been pretty easy to make from hex bar stock in a conventional lathe. Then again, hardened steel is the kind of material that wire EDM was made for, and there seem to be many use cases for an attachment that can spin a workpiece against an EDM cutting wire.

That was really the trick of this build — spinning a part underwater. To accomplish this, [BAXEDM] built a platform to carry a bearing block that supports a standard ER-25 collet, with a bracket that holds a stepper clear of the water in the EDM cutting tank. There are plenty of 3D printed insulators too, to keep most of the attachment electrically isolated from the EDM current, plus exotic parts like ceramic bearings that won’t corrode under water. There were a ton of other considerations, too; [BAXEDM] goes through the long iterative design process in the video below, as well as taking his new tool for a literal spin starting at about the 27:00 mark.

If you’re intrigued by what EDM can accomplish — and who wouldn’t be? — but you need more background on the process, we’ve got you covered.

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