Desktop EDM Hack Chat

Precision parts, one spark at a time

Wednesday, June 28, 2023 12:00 pm PDT Local time zone:
Hack Chat
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Cooper Zurad will host the Hack Chat on Wednesday, June 28 at noon Pacific.

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Whether you know it or not, chances are pretty good you've run into the results of electrical discharge machining at some point. EDM is the go-to machining method for so many applications, from making complex injection molding tooling to putting impossibly small holes into hardened steel, EDM gets the jobs that make traditional machining techniques weep.

At its heart, EDM is really simple; it's just making sparks to selectively erode metal. In practice, though, it's way more complicated than that. There's the CNC aspect to control the cutting tool, the dielectric to cool things and flush away the swarf, and the precision control of the electric discharge. It's all just complicated and expensive enough that it's hard to find anyone doing EDM on the hobbyist level.

Hard, but not impossible. Desktop EDM is doable, and to help us understand the challenges involved we've invited Cooper Zurad to the Hack Chat. Cooper has quite a bit of experience with the related and somewhat less energetic ECM, or electrochemical machining, and is now turning the knowledge gained there to desktop EDM. Make sure to join us with your questions about machining with electricity.

  • Hack Chat Transcript, Page 4

    Dan Maloney06/28/2023 at 21:15 0 comments

    Thomas Shaddack1:54 PM
    I tried 0.1mm wire, handheld. Was thinking about feeding it through a glass capillary and using a mechanical sensor on the capillary for the we're-too-low signal.

    Cooper1:54 PM
    that's a really good idea using a glass tube

    gedm-dev left  the room.1:54 PM

    Thomas Shaddack1:55 PM
    Didn't do spark counting, was considering partially overlapping circles being bitten out of the copper.

    Cooper1:56 PM
    I would think it would be hard to get a super clean line in the copper.

    Cooper1:56 PM
    I will have to head out soon. Are there any lingering technical questions?

    Thomas Shaddack1:56 PM
    The question is, how hard it is to get clean-enough line.

    Cooper1:57 PM
    You'd have to try it on a machine to find out

    Thomas Shaddack1:57 PM
    Yup. Didn't get enough round tuits yet.

    Cooper1:58 PM
    get one. they're so worth it

    Thomas Shaddack1:58 PM
    About to play with some elastomers. Printing gaskets, and wearables.

    Thomas Shaddack1:59 PM
    Gaskets are an issue for fluids-handling.

    Thomas Shaddack2:00 PM
    Wrote some software earlier for gcode generation for drawing on fabrics, dot by dot, by just touching the surface from top-down and then retracting and going to another pixel. Eliminated issues with lateral forces on the pen and the fabric wrinkling. Can be also handy for spark-engraving surfaces.

    Thomas Shaddack2:01 PM


    Read this on Improwis

    Thomas Shaddack2:01 PM
    May be an idea handy for something.

    Cooper2:02 PM
    Sweet! I'll take a look

    Nicolas Tremblay left  the room.2:02 PM

    parascubasailor2:02 PM
    Hello everybody! Sorry I'm joining so late. Currently at work.

    Cooper2:02 PM
    👋 I think we're just about finishing up now. Do you have any questions I can answer before I go?

    parascubasailor2:04 PM
    Scrolling back to get an idea of what went on...

    Dan Maloney2:04 PM
    I'll be posting a transcript in a minute

    parascubasailor2:04 PM
    No questions (yet)...

    Is your stuff here on Hackaday? Will probly refer to it later.

    Dan Maloney2:05 PM
    Plus Tom Nardi usuallyu does a nice summary article on Friday

    Cooper2:05 PM
    I'm going to be heading out soon.

    Cooper2:05 PM
    Let me say thanks so much for having me, everyone! It was a ton of fun to chat about EDM. I loved all the great questions and appreciate everyone taking the time to chat!

    If you want to follow what we’re doing, here’s our links to follow:

    Discord Chat:



    Kickstarter Updates:

    Website Email List:

    Dan Maloney2:06 PM
    Thanks Cooper, this was fantastic. I really appreciate your time today!

    Cooper2:06 PM
    I appreciate you having me. I love to nerd out to EDM and related processes so this was a real treat!

  • Hack Chat Transcript, Page 3

    Dan Maloney06/28/2023 at 21:14 0 comments

    Cooper1:09 PM
    There are limitations to a rod-based process, but there is nothing else commercial out there that can do this at this price range. We view this as a great start and taking desktop EDM from 0 to 1.

    Cooper1:10 PM
    @Thomas Shaddack I believe it would work with sintered brass or copper. I would love to try it

    gedm-dev1:10 PM
    If it cuts 2mm steel and drills 40mm holes into steel I buy it. Is it possible?

    Cooper1:10 PM
    There is a company Sapphire 3D that we have been talking to

    Thomas Shaddack1:10 PM
    Virtual Foundry has the filaments. Or, if you want to skip the printing and go hand-moulding, metal clays or art clays, they come in copper/bronze/silver (and gold).

    Cooper1:11 PM
    I have not tried either of those cuts so I could not tell you one way or the other

    gedm-dev1:11 PM
    Do you think it is possible?

    Cooper1:11 PM
    Virtual foundry looked cool. I would like to check that out.

    Bharbour1:12 PM
    Is the metal in thermoplastic binder conductive before burning out the binder?

    Thomas Shaddack1:12 PM
    Would be a great thing for eg. gears. No need to stock all the billets, all the diameters we may need, and remove inly a small fraction of the material, wasting little.

    Cooper1:12 PM
    I think for gears you'd ideally just be doing wire EDM on those, depending on size

    Thomas Shaddack1:12 PM
    Nope, I assume. The percolation threshold for decent conductivity is hard to reach.

    Cooper1:13 PM
    Oh are you referring to the tool as a printed part?

    Cooper1:13 PM
    @Bharbour yes it is metal powder in a binder filament

    Cooper1:13 PM
    @gedm-dev probably. You'd have to try it out

    gedm-dev1:14 PM
    What if I told I have and found out that it just won't work?

    darkomenz1:14 PM
    You would likely have to fully process the part.

    Cooper1:15 PM
    I would say to change parameters or tool geometry and to try again. EDM is a very complex process with a lot of ways to get things right

    gedm-dev1:15 PM
    I'm serious about it. Don't let people think they can mount an EDM unit to a printer and cut steel. I ripped apart GRBL to the core and compared it to Marlin. The core looks similar. And no. It won't work.

    Cooper1:15 PM
    I generally recommend cutting aluminum with the Powercore. That's what we've had the most success with and what we've described in the Kickstarter. There is a lot of testing to be done on steel to find the limitations.

    Cooper1:16 PM
    If you were to use a wire tool you'd probably be doing great with steel on a 3D printer

    Thomas Shaddack1:16 PM
    Are the limitations hard ("impossible") or soft (just s-l-o-w)?

    Cooper1:16 PM
    a wire is ~8x smaller in diameter than the rods we use right now. So it will cut around 8x faster through the same material.

    Dan Maloney1:17 PM
    And really, there's a lot to be said for being able to mill parts on a desktop with a repurposed printer, even if it's "just" aluminum

    gedm-dev1:17 PM
    I know. But everyone who have ever cutted hard steels and Aluminum know that Aluminum is like cutting a paper with a chansaw. This will work more or less good. But steel is something different.

    Cooper1:17 PM
    @Thomas Shaddack it is not impossible. The sparks erode steel. I do not have a lot of hard data on feeds and speeds yet but there are about to be 420+ people with the means to find out.

    Thomas Shaddack1:18 PM
    Was thinking about a variant. A small-size high-accuracy EDM, for turning wasted pieces of carbide drill bits into taps or dies or single-point turning tools.

    darkomenz1:18 PM
    EDM is known to cut laterally any material that is conductive. This included hardened steels I am sure its just a matter of good process control.

    Cooper1:19 PM
    Yes. Like I said, the sparks to remove material. You're probably going to be running ~3x slower in any steel stock when compared to aluminum of the same thickness.

    gedm-dev1:19 PM
    @Cooper What is the minimum feedrate that a normal Ender can provide?

    Cooper1:19 PM
    The wear ratio is also worse with steel.

    Cooper1:19 PM
    @Dan Maloney I agree. I am excited to try out some extruder and hotend...

    Read more »

  • Hack Chat Transcript, Page 2

    Dan Maloney06/28/2023 at 21:12 0 comments

    gedm-dev12:32 PM
    Ok. My bad. Just searched a little and found an old discussion on the topic and that it will be hard work to implement.

    gedm-dev12:33 PM
    Does negative feed completes a full line segment or can it ride the line back and forth to any position until reversed?

    Cooper12:33 PM

    2 MB

    Download File

    Cooper12:33 PM
    This video is of 4mm aluminum we cut on the Ender 3

    Cooper12:33 PM
    one sec I will add a pic. Thought the video would embed

    Cooper12:34 PM

    Andy Pugh12:35 PM
    @gedm-dev It runs the whole G-code program in reverse.

    gedm-dev12:35 PM
    Until stopped? Let's say it just want to retract a tiny segment of the line and then go back. Possible?

    Cooper12:36 PM
    @Andy Pugh that sounds perfect.

    gedm-dev12:36 PM
    Does it handle arcs as well?

    Cooper12:36 PM
    I would guess it only runs in reverse until the trigger is not flipped for that to happen

    Andy Pugh12:37 PM
    @gedm-dev It runs backwards as long as the adaptive-feed is negative, stops if it is zero, runs backwards at hald speed if it is -0.5. backwards at double speed if it is -2 etc etc

    gedm-dev12:37 PM
    I forked grbl and made it usable for EDM. And decided against reversing the full GCode since arcs would just be a pain to reverse.

    Andy Pugh12:38 PM
    The idea would be to program a feed faster than the cut, and have the controller adjust the speed up/down/reverse to manage the cut.

    Andy Pugh12:38 PM
    @gedm-dev Watch the video I linked above.

    Cooper12:38 PM
    The video shows an arc

    Cooper12:38 PM
    Very cool stuff.

    Dan Maloney12:39 PM


    asadurkee joined  the room.12:39 PM

    Thomas Shaddack12:39 PM
    In marlin, delta printers convert straight lines into very short segments that are straight-enough. Could this be leveraged for the retractions?

    Cooper12:39 PM
    That was John, my co-founder who made that video.

    gedm-dev12:40 PM
    If it works it works. I don't think it is too hard without adjusting feeds. The feed should normally be created by the feedback itself. In my first tests I tried using some PID controlled feedrate adjustments. It worked somehow. But other ways turned out to work better.

    Thomas Shaddack12:41 PM
    Can the electrode wear be compensated by taking periodic checks by touching the electrode against eg. a touch probe?

    gedm-dev12:41 PM
    @Andy Pugh nice work. Must be brutal to get running to that point.

    Cooper12:42 PM
    Thomas, this is normally not necessary or ideal. It is best to work with a known diameter tooling and to just move to a "clean" portion of it

    Andy Pugh12:42 PM
    @gedm-dev That's what I was meaning, the programmed feedrate is set "out of the way" of the system, just because G-code needs one, and then the entire process is managed by a PID (or similar) that controls the adaptive-feed pin to achieve the desired arc voltage (or whatever the actual process variable is)

    Cooper12:43 PM
    Wear ratio between tool and work is generally pretty consistent. Once you nail down the feed rate for a given matl you can use that

    Ethan.Hall joined  the room.12:43 PM

    Nyles12:44 PM
    Interesting - so what is the best combo of process variables you've found?

    Dan Maloney12:44 PM
    In practical terms, can you swap a printer back and forth from FDM to EDM? Or are you better off just buying a dedicated printer for EDM work?

    Cooper12:45 PM
    Nyles that is a pretty complex question lol

    Nyles12:45 PM
    Yes it is :D

    gedm-dev12:45 PM
    Hi Ethan.

    Cooper12:45 PM
    We define wear ratio as the ratio between XY motion and the necessary Z movements.

    Cooper12:45 PM
    For thinner aluminum or titanium you can use a low ratio like 0.03

    Cooper12:46 PM
    For thicker stuff you'll need a higher ratio. We've set things up like this not because it will make a perfectly efficient process, but because it will be easy for people to use.

    Cooper12:47 PM
    Dan, you can absolutely swap back and fourth. It is a rather fast process on the Ender and we have done so a few times. If you plan on doing a lot of EDM it might be easiest just to have...

    Read more »

  • Hack Chat Transcript, Page 1

    Dan Maloney06/28/2023 at 21:10 0 comments

    Cooper11:44 AM
    Hey guys, I'm a bit early but here's a great starter on desktop EDM:

    Dan Maloney11:44 AM
    Hi Cooper, welcome to the show!

    Cooper11:44 AM
    Finishing up some stuff but I will be ready for questions noon pacific time

    Cooper11:44 AM
    Hi Dan!

    Dale Grover joined  the room.11:51 AM

    Cooper11:58 AM
    aaaaand I'm back

    Dan Maloney12:00 PM
    OK, then, let's get started. Dan here, I'll be moderating today along with Dusan as we welcome Cooper Zurad to the Hack Chat for a discussion about Desktop EDM. And apologies in advance for the inevitable typos -- getting used to a new keyboard here.

    Hi Copper -- want to get us going with a little bit about yourself?

    Nyles12:00 PM
    I remember that video, good stuff.

    Cooper12:00 PM
    Thanks, Dan.

    Dan Maloney12:00 PM
    See? Copper != Cooper.


    Cooper12:00 PM
    Hi everyone! My name is Cooper Zurad. I have years of experience in electrochemical machining (ECM) and have recently been developing electrical discharge (EDM) systems. All of this work has been on desktop processes.

    I am co-founder of a company called Rack Robotics. We produce affordable EDM power supplies meant to convert your 3D printer into an EDM machine.

    We are close to shipping our first product, the Powercore. We launched this project on Kickstarter

    a few months ago. Link here: [](

    If you want a quick rundown on how the Powercore works and how it can convert your 3D printer to an EDM machine, check out this great video by my co-founder, John:

    Other than that, I’m open to any and all questions regarding desktop EDM and it’s future. Excited to be here!

    Nicolas Tremblay joined  the room.12:01 PM

    andymid2001.3d joined  the room.12:01 PM

    Nyles12:02 PM
    How do you deal with electrode wear?

    Cooper12:02 PM
    Electrode wear is an interesting problem

    Cooper12:02 PM
    There are several ways to deal with this

    Cooper12:02 PM
    In our current implementation we move the electrode downwards in the Z axis as we cut in the XY plane

    Cooper12:02 PM
    this allows us to have a consistent kerf width in the process

    redfast0012:03 PM
    I'm interested in using EDM for 'drilling' deep, precise holes in metal. The problem I see when using the powercore with a 3D printer, is that chips would be stuck in the hole. How do you deal with this?

    Cooper12:03 PM
    To do so we've forked LaserWeb4 and added a custom post processor

    redfast0012:03 PM
    (where deep > 100 mm)

    Cooper12:03 PM
    Redfast, I would recommend remixing the EDM tool holder to allow thru flushing of dielectric

    Cooper12:03 PM
    The files are on our printables page. Link incoming.

    Cooper12:04 PM
    This would allow the waste to be removed consistently

    Cooper12:04 PM
    Files + CAD here:

    Dan Maloney12:04 PM
    Do you need a hollow electrode for that? Or will a standard brazing rod do the trick?

    Cooper12:04 PM
    Yes, Dan, you'd need a hollow electrode.

    Thomas Shaddack12:05 PM
    Would an injection needle work? In effect it is a stainless steel tube.

    Cooper12:05 PM
    The files are now setup for solid rods as we've focused on emulating the function of a fiber laser on desktop. But the CAD is available for remixing

    Dan Maloney12:05 PM
    Does that leave a "slug" inside the electrode>

    Cooper12:05 PM
    Thomas, I would not recommend it. I've used those for ECM plunging, but you really want brass or copper for EDM

    Nyles12:06 PM
    How do you 'mill' out the bottom of the hole with the hollow electrode?

    Cooper12:06 PM
    Dan, yes it would leave a slug if it was a blind hole.

    Photon joined  the room.12:06 PM

    darkomenz12:06 PM
    The edm electrodes for drilling are not just plain pipes.

    Cooper12:06 PM
    Let me find and image for you Nyles. There are specialized electrodes for drilling blind holes

    darkomenz12:06 PM
    They usually have several smaller...

    Read more »

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