Capacitive Discharge Spot Welder Update


It seems one of our commenters took great umbrage with [PodeCoet] not documenting his capacitive discharge cutting properly. [PodeCoet] had been waiting till he got the full spot welder working before publishing, but he’s expedited the work after all our whining. Check out his full writeup of the device in its current state. It uses a 1Farad audio cap for storage. A dsPIC monitors all of the voltage sources and regulates charging. A nice touch is the tactile switch on the electrode.

22 thoughts on “Capacitive Discharge Spot Welder Update

  1. And he sure seems to know what he’s doing, both electrical as well as mechanical, and he made a very nice video, his flaw is that he doesn’t make nice housings I guess, nor does he wear protection like gloves and he hangs a (flammable probably) flag from a wooden table on which he’s welding, generally doesn’t go the full nine yards on safety I must conclude.
    Seems curious since he must have had proper training but his school disregarded that aspect largely it seems to me.
    Still if that’s the worst of it, better to have a good project without much safety than a shoddy one with safety.

  2. Jesus, cut the guy some damn slack! You make it seem like he owes you this. I’m getting rally sick of the vocal minority of posters on this site to whom nothing is ever good enough. Put up or shut up wwhat.

  3. this is an outstanding project. and he’s taken time to document it, it seems, at the request of hackaday readers. outstanding work. of course, there will always be someone with a bigger hack-peen that bitches.

  4. That’s a pretty class act of him, to still put up a decent write-up after the ingrate in the previous post. If you can bite the hand that feeds you, and the hand doesn’t stop – then the owner of that hand is pretty cool.

  5. A very nice write up! I think you should post some schematics and such for those of us that could use one. *hint hint*

    It really is a shame that some people who will remain nameless *cough*egotastical*cough* could make the rest of us look like jerkoffs.

  6. I too would prefer that *some people* not make all hackaday readers look like jerkoffs. ;[

    All-in-all, an awesome write-up, and a pretty slick piece of gear. But as smart as I am, I would be hard-pressed to figure out how to make my own from the information presented. A little more detail on the workings of the hardware would be greatly appreciated.

    Also, his write-up on the flashlight mod was hilarious. Especially the disclaimers.

  7. Great writeup. I suspect it really is the vocal minority on sites like this that are just never statisfied. I know that all my articles that got put on this site always have a mean comments. I just ignore those posts and don’t stress myself out trying to figure out how to respond to them. I take encouragement from knowing that most people who appreciate the articles don’t comment. For instance I appreciated the first article, but didn’t comment. It helped get me thinking about what is possible. This update and the possible future updates will also be appreciated.

    I did a little reading about electric discharge machining. I’ve seen some reference to using a fluid (like Kerosene) to prevent oxidation. I imagine this would also help get rid of the sparks. Does anyone know if putting an inch or two of a fluid on top of the plate you’re cutting would get rid of sparking and make cleaner cuts?

    I have an artist friend who could probably create some really amazing things with a tool like this.

  8. @ribblem: You’re absolutely right, and those that moan the loudest probably aren’t even interested in building the project or doing anything constructive, just in having a forum to complain about something, anything.

    Props to those who actually step away from the internet to build something in real life!

  9. It looks quite impressive…and also pretty complex. I don’t think it’d be easy to replicate, at least not simply or (relatively) inexpensively. :( The author / creator does get my respect for an awesome project, though!

  10. Whenever I see such a nice, neatly built project it makes me want to build one right away even though I have no idea what I could use this for ^^

    To people complaining about other people’s complaints : there were only 2 or 3 negative comments in the other thread, why focus on these ? You can’t have 100% approval every time.

  11. I kind of agree with the calling of this guy a “class act.” Apparently we seem to have people who think that someone who has an idea is obligated to share schematics with full step process build instructions. The fact he even accommodated us is amazing in its own right. While I have had enough capacitive spot welding by accident, and have no interest in this particular project, I do applaud the fact that this man is very generous with the community here. Thank you sir.

  12. Let me be counted among those who applaud podecoet for responding to my riposte with generosity and revelation. I knew it might hit a nerve, since he and I probably travel similar paths.

    I agree with many of you: We have no right to demand any action from any author, hacker or inventor not in our employ.

    However, we have every right to criticize even the most worthy of men (identifiably or anonymously) – and the most interesting thing about criticism is this:

    A worthy man will always respond not to the criticizer, but to the criticism itself.

    I would submit that podecoet is therefore a worthy man. He reprinted my post, but rather than attack me, he documented his project! *

    > Does anyone know if putting an inch
    > or two of a fluid on top of the plate
    > you’re cutting would get rid of
    > sparking and make cleaner cuts?

    Yes, but there are additional issues from doing this – it isn’t very clean and you have to circulate the fluid.

    In his first video, he was using it as a free form cutting tool to cut shapes out of sheet materials by hand – and I’ve never seen anyone do this before. It’s an interesting idea for sculpting.

    I’m playing with an XYZ gantry to do something similar to this (it’s a CNC mill, basically) and the cool thing about EDM is that you can cut very fine shapes and drill holes that you can’t really do easily with end mills.

    A lot of people use lasers, but lasers have their own issues – EDM can cut reflective materials and has some advantage. You can blow inert gases over the working discharge with good results – you get less burning of the material.

    There isn’t a big call for it, but my problem is to make a bunch of parts out of thin reflective metal stock. For me, an EDM flatbed plotter is the perfect solution, mostly because I can’t economically use big laser cutters on such tiny one-off items (usually under 2″ in diameter).

    PS – despise me if you will, but I would have reacted in the same way to such a comment, which is why I worded it as I did. Really creative people ALWAYS have egos to match – it goes with the territory. They’ll often deny it, but empirical data shows otherwise.

    Again, to podecoet: Sorry for my technique, but I just wanted to grind a specific axe. BTW, good luck with your business ventures!

  13. Hey, thats awesome that this guy took time to document all of this for everyone. We all at sometime tend to forget that people place stuff on the internet have lives and other things going on too. It is a privilege that they share with up not a requirement or right. I applaud this guy for sharing with use. Thanks.

  14. “Under no circumstance leave out the ability to switch the output, especially if you use a high-current charging supply (you will blow your rectifiers and/or smoke your transformer if the electrode gets stuck!)”


    Why can´t i just, let the capacitor connected to the power supply and switch the output?

    if the capacitor gets fully loaded, it´ll stop getting current from the transformer.

    I didn’t understand why if i switch the output and not the input will blow the rectifiers or the bridge.


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