Capacitive discharge cutting

capacitive discharge cutting

Capacitive discharge cutting provides more control than linear transformer versions. A very large capacitor is charged to a precise voltage and then discharged through the material to produce a controlled cut. The same device can also be used for spot and tab welding. A video of copper roof flashing being cut is embedded below. An example of a linear transformer can be found in our our How-to: build your own spot welder.


  1. nemo says:

    that looks scary and very dangerous, but awesome.

  2. nio says:

    That’s GREAT!!!

    Any schematic/explanations on how it’s done ?

  3. sean says:

    Hmm, combine this with CNC and…

  4. Steve Watkins says:

    The scematics are supposed to be uploaded somewhere. I could not find them on his site.

    There are some other interesting projects there as well.

  5. kabukicho2001 says:

    What capacity is the huge condenser? 50,000 uF? and power supply is a pc one? 12 V I think..

  6. zake says:

    nemo:”that looks scary and very dangerous”

    And that’s how we like it 8)

  7. tapius says:

    @sean exactly what i was thinking haha this looks awesomely accurate the edges are pretty clean

  8. eraser says:

    I need to order one!
    add to cart or “Buy” link is gone.

    How do I get one coming now?

  9. eraser says:

    dang it, i posted on wrong post. sry

  10. Wolf says:

    Looks awesome, but the electrode seams to heat up really fast. Running an air jet over the electrode might help, it may even increase the cutting action for thicker metals.

  11. Gilliam V. says:

    He cut the circle, triangle, and square in the can. but wheres the “X”?

  12. cirictech says:

    SO I must have one of these, if only o cut small stuff it would be really cool.

  13. egotastical says:


    This guy doesn’t share, period. He’s into glory, not the greater good. I wouldn’t waste time looking for schematics or code. What looks like a cool invention is just one man’s implementation of well-known prior art; maybe you could pay him for the details.

    Or not.

    Anyway, this is F’ing trivial to do, and all you have to do is google amateur EDM or capactive discharge machining. It’s basically the opposite of welding. You also don’t need a micro to do it, you can create PWM waveforms from trivial analog circuits and some gates.

    Here’s a start, using a PIC programmed in BASIC. Mind you, these people are not exactly rocket scientists, but they don’t treat everything like a top secret VC wankfest, either.

  14. nimitzbrood says:

    This is very similar to a process called Wire EDM:

    And yes it’s pretty cool. ^_^

  15. smilr says:

    jeez – who pissed in your cereal this morning egotastical? I for one did not even know that this was a commonly used machining technique.

    Whether he shares his implementation details or not – this guy deserves some accolades for building one of these himself. You claim an effective unit can be built without a microcontroller – so get out there and _DO_ it, rather than bitch about this persons work.

  16. andres says:

    wow, thats a very clean implementation. i could see that being very usefull for fabricating small parts. hope he puts out some more specs soon! very good job.

  17. thethirdmoose says:

    I wonder if you could mill PCBs with this and CNC

  18. em says:

    Some more details would be nice but it is up to steve to release as much or little info as he likes.
    Steve isn’t forcing anyone to look at his work.
    I’m with smilr – egotastical is free to upstage Steve if he feels so inclined.

    As someone who does put much of what I do online I know it take a lot of time andSteve may simply be too busy building to do much writing.

  19. PodeCoet says:

    Hey guys,

    Gah, I was hoping to complete this first, but someone submitted it to hackaday before I got the chance.

    In short, YES, I will be releasing the schematics, PCB layouts and Firmware to boot, as soon as I finish bugfixing the spot-welding portion. I’m a little busy with work for the moment, so it’s a couple of weeks yet.

    There’s a little more info on my other website; – Once completed I will be posting the designs/layouts there for download. Thanks for your feedback!

  20. theweirdness says:

    bet you feel like an ass now egotastical?

  21. sven says:

    hope he was wearing UV goggles of some description.

  22. cbob says:

    Having welded in another life, I can say that was cool & I want 1. However, get some cheap welding gloves. The 1st few times you pick tiny bits of metal out of your skin it’s kinda neat/weird. It gets old fast tho. Handheld EDM…See what I missed out on (sniff)

  23. PodeCoet says:

    Hello again,

    I’ve just finished a write-up for you guys due to a suprising number of emails. It’s not much so far (and I apologise as I’m out of time), but it should get you well on your way to making your own device:

    Snippets of source as well as detailed pictures are there for now. Source, layouts and schematics will follow in a couple of weeks – I hope this clears up any misconceptions.


  24. teck monkey says:

    i want i want i want :))) and egotastical grow up as others have said maybe the guy is busy or not so inclined to share ether way who cares im going to be spending the next few hours researching this class of device for other ways of building… its a cool concept and just the kind of thing thats spurs me to look for more.

  25. bakadrh says:

    This is great! I want to suggest that a small amount of shielding done with an inert gas will increase the cleanliness and precision of the burn by displacing the oxygen available to oxidize the metal into a fume. Argon or nitrogen works but may not be available to the home DIYers. CO2 from dry ice might work, since the Carbon makes a good bond with the Oxygen. Regular compressed air could be an advantage since it’s about 79% nitrogen; however one would need to play with the volume and velocity to optimize the cut (I started playing with that using a pump up sprayer about 20 years ago but lost the priority). Just a word of caution, zinc metals are a bit toxic so exhausting the fume will help you enjoy the weekends more. ->take care, and thanks for sharing! –bakadrh

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