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.

12 thoughts on “Hackathon Wire EDM Build Really Works

  1. Am I right in thinking this EDM machine can only do cuts right through the full depth of the workpiece material (laser cutter or waterjet style) and not partial depth cuts the way a milling machine could (although couldn’t easily on the hardened metals EDM can cut)?

    1. This type, yes. It’s like a band saw. But the electrode can be made in various shapes depending on what needs to be machined, it doesn’t have to be a spool of wire.

    2. As others have said, yes, wire EDM is for through part cuts. There’s another style called sinker EDM that plunges a tool (typically carbon) into the part that can make blind holes. It works on a similar principle where sparks of electricity break off pieces of material but instead of the tool being a wire, it’s a formed solid piece. Now, the details of how precise they can get, how fast to tool erodes, etc. I don’t have. I’ve never used one but worked with a machinist years ago that used to run one. The only thing like it I’ve used is a tap burner that will eat a broken tap out of a hole. It was a crude device that could save a week’s worth of effort from a broken tap.

        1. FWIW another way to do this is warm dilute sulfuric acid, like room temperature 5% or so, left for quite a while, like a day. It’ll eat carbon steel and high speed steel like a thousand times faster than it’ll dissolve either aluminum or titanium. I use Sparex #2 at 40C to do the same.

      1. I ran ram aka diesinker EDM for a few years. Just google old EDM hackaday articles, you’ll find some of my descriptions on running them. Might have been when I just went by Drew, as I did for years, then someone showed up started using that name, so I got more specific.

        Tap burners are a simplified version of ram edm optimized for quickly burning through broken taps and bolts for removal.

        Ram, aka diesinker EDM can burn all the way through something, or part way. It can also be used like an electrochemical milling machine- many have the ability to spin the spindle and use a round electrode like a fluteless endmill, burning a path or shape away. The ones I used could do this.

        Wire EDM is like an electrochemical scrollsaw for metal that you can thread the cutter inside a workpiece through a predrilled hole, but however you do it once the wire is threaded from the top to the bottom guide you can cut the part in any direction like a wire cheese cutter for metal. 5 axis wire EDMs can actually cut tapered parts, and shapes that transition from completely different shapes on the top of the cut to the bottom of the cut by controlling the top and bottom of the wire guide completely separately.

  2. Very interesting. There are also pulse EDMs that are called ram EDMs. They don’t use a wire but a solid that’s pushed into the workpiece. On YouTube there is a channel called @myengines2443 where someone build one.

  3. I wonder, if I were to take a cheap wire welder and feed the wire back into itself in a loop, guiding the wire through a tank of oil, being circulated by a fan.
    I wonder it this would work with such thick wire, if the speed was dialed in just right.

    1. The professional machines use output monitoring to dynamically adjust feed rates, and current thresholds. This is why a 2 pass EDM can hold such ridiculously good tolerances, as the wire/ram is never supposed to even touch the metal stock.

      Additionally, the driver is not just some random mystery sparks. There are a lot of papers that explain why it is often a fixed 30% On-duty 1MHz 60v (accurate, but slow cuts) to 110v (faster cuts, but sloppy) output is used. There are also several variations on the electrode drive waveform for exotic materials. Yet, a wire EDM rarely needs more than 6A to cut through thick material… Rams with mold cutters have much more surface area… and much higher power requirements.

      Why a slow second skim pass is often needed to trim off the chowder you may ask? Mostly deformation in the metal as stresses are relieved. Notably, drop-forged and cold-rolled metals will usually deform even during traditional milling, and can bind/pinch the wire no matter how careful the operator. A roughing pass is still recommended on annealed alloys and carbides for different reasons (the papers dig into why this anecdotal habit became standard practice).

      Used self-threading wire EDM machines can be found for under $5k, but moving large machines around is usually unfeasible. They are heavy, messy, electrically noisy, and often 3 phase industrial power only (our EU friends are better off in that regard). Software can be tricky, but LinuxCNC documents many retrofits ( Andrzej Maciąg did this project if I recall).

      Highly useful process if time is not a constraint, and always remember most carbide powder is tumorigenic. Always protect yourselves and the community around your shop. =)

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