3D Print Yourself A Flame Thrower

For a large proportion of the world’s population, it’s now winter, which means there’s plenty of rain and snow to go around. With the surrounding environment generally cooler and wetter than usual, it’s a great time to experiment with dangerous flame based projects, like this wrist mounted flame thrower.

It’s a build that does things in both a simple and complicated way, all at once. Fuel is provided by a butane canister with a nozzle that needs to be pressed to release the gas.  A servo is used to push the canister into a 3D printed housing, releasing the gas into a pipe to guide the fuel towards the end of the user’s wrist. The fuel is then ignited by a heated coil of wire. The heated wire and the servo are both controlled by standard radio control gear typically seen on RC cars or buggies. Using the brushed speed controller to run the heated coil is particularly off-beat, but it does the job admirably.

Overall, it goes without saying that this build presents some serious risks of burns and other injuries. However, the fundamental premise is sound, and it does what it says on the tin with parts that could be readily found in the average junk box.

For another take on a wrist-mounted flame thrower, check out this version using a scavenged solenoid valve.

20 thoughts on “3D Print Yourself A Flame Thrower

  1. Look, I understand the premise behind taking ideas and iterating and improving them that this site generally focuses on.

    But urging users to use junk bin parts for every single project just seems a bit too reckless. Does it not?

    The servo sticks or the cheap 3d printed part fails and the unit both suddenly starts to dispense far more material than initially assumed, combined with the fact that there is no e-stop and the canister is physically attached to the user. Things can go very wrong, very quickly here.

    Presumably most people competent enough to put this together would at least understand that and this person appears to have at least taken a few minor precautions but not really enough if this build suddenly fails catastrophically and cutting corners to make things cheaper only serves to increase the chances of that happening.

    Also, I also see no rain or snow in the photo.

    1. But you are happy to sit in a metal box travelling at 60mph separated from others in their metal boxes, also doing 60mph in the opposite direction, by a white line painted on the road?
      No one is being urged to do anything, we’re simply being shown what others have done.

      1. I am not sure I would use the word happy.

        Motor vehicle accidents kill approximately 1,250,000 people worldwide every year. Roughly 150,000 people die every day. Roughly 360,000 births happen every day. Motor vehicle accidents are hardly the greatest cause of death worldwide but it is also something with significant room for improvement that would make a meaningful impact on death rates if we could improve this. Also note that those numbers do not account for disabilities or other injuries, which are also significant.

        If one worked in the medical field or was remotely aware of worldwide motor vehicle statistics or studied the engineering behind vehicle crash events, they are very likely to not be terribly happy with the current state of transportation compared to how things could be.

        Things are improving. Albeit not very quickly.

      1. Unclear why you needed to bring gender into this? The project is a combination of somewhat high probability of catastrophic problems combined with loose tolerances. That’s the only part I have issue with. Not all “hacks” have to be precision engineered but the ones that can go poorly should have a bit more care and attention put into them is all I am suggesting.

  2. I can’t Print anything now…
    I will keep it simple…..
    I drilled a hole threw the controller board.
    And my router gave the magic blue smoke and last but not least I now need a new vacuum cleaner.
    And that’s just the morning.
    Lets see what the afternoon does.

    I know DRILLED a friggin hole in it.
    I even had a board in front of the drill.
    But the bit lifted up my protection.

  3. I don’t get it. What’s with the fastination with 3d printed weapons? No, I’m not against people owning weapons. But if you want to build your own then go out and study metal working! Fire, explosions and heavy impacts are not the sort of thing 3d printed plastics are good for!

    But if you must then at least call it what it is… Printing your own Darwin award!!!

    1. Because a $200 3D printer is a LOT more accessible than $10,000 in machine shop equipment.

      Don’t get me wrong, I’d love a CNC mill, metal lathe, press brake, arc welder, and everything else, but some of us aren’t rich. We do what we can with what we have where we are.

      1. You can even do much with hand tools if you want or have to. 3D printers are nice, but I am also no fan of plastic weapons. The few times I used a weapon was for target practice. So precision was most important. A plastic piece can not beat a Glock or (at the military) a rifle.

        Of course I also played with butane lighter refill cans when I was much younger :-) There were no 3D printers for years to come but a piece of silicone tubing and a piece of stainless steel tubing is enough for some fun. :-)
        At least if you do not have the urgency to strap it on your body. If I would want that, I would also think about more heatproof materials. Perhaps a metal can of suitable diameter as the container for the butane can with a brass nozzle (tubing) soldered in and wrapped in leather to attach leather strips (leather does not melt and is quite heat resistant and insulating).
        But in fact I can not see very much details on the photo. There is some distance between the nozzle and the bottle, in between seems some (copper?) tubing.

  4. a small while ago, hackaday featered a similar device/contraption
    https://hackaday.com/2017/11/17/cheap-flamethrower-is-predictably-worrying/#comments

    Then we’ve found out that not everything that produces a flame is a flamethrower.
    quoting Aka the A : “Not a flamethrower, since it doesn’t throw burning liquid/gel anywhere… this is a torch.”
    And this project is no different.

    I like the care and design considerations that were put into this design… but it remains a dangerous contraption!
    Please be careful and “don’t do this at home” (or anywhere else).

  5. We are all going to die eventually, just some will die sooner than others. Some hope to live for a long time, some don’t care (just enjoy it while it lasts), and a few seem eager, and in a hurry to get it over with. Most you boys (some that never grew up), have played with some dangerous, crazy ideas. Some die or get seriously hurt, some learn to be more safety cautious, others will discover what makes it dangerous, and correct the problem, sometime stumbling onto something useful in other applications We are all free to make our own choices, choose a path we’d like to follow. It’s not right to condemn others for living by their own choices.

  6. Man… have you ever tried to reshape PLA with a lighter before? It’s pretty flammable and it sticks like napalm (well, not quite that horrible but whatever). Looks like anything that will ignite the PLA also means you have bigger problems though. No idea what the flexible glove stuff is like when heated.

  7. IMHO it would have been way cooler had he mounted it to his head, used two cans and had the outlets coming out where his eyes would be. Perhaps mounted on a pair of sunglasses or something similar. With that sort of setup you could simply look at the things you wanted to “roast”. /s

  8. A thin plastic piece of “armor” with a low melting point that is fastened with 4 nuts and bolts to your arm protecting you against butan gas initiated flames.

    What could possible go wrong?

    P.S. I advice to use lock nuts.
    Makes it all more YOLO.

    1. what could possibly go wrong… haha…
      but just because you’d asked:

      -The servo could get stuck,
      -The igniter might fail completely
      -The igniter may switch on too late (heat up time takes too long or unexpected cooling due to wind conditions)
      -The flame goes the wrong way due to heavy wind or sudden arm movements
      -The cold gas might freeze his hand
      -The molten plastic could burn his hand
      -His clothes might catch fire
      -His curtains might catch fire the moment he walks into the house again but forgets to switch it off and then -Accidentally presses the “fire” button
      -He might hurt innocent bystanders
      -The circuit controlling the servo might trigger falsely on an unexpected moment because the neighbours are testing their RC-card on the same frequency.
      -The battery could explode… they seem to do so (although most times there is a “valid” reason)
      -The plastic might break (because it gets brittle because of the low temps caused by the expanding gas) and cause gas leaks.

      In the video at 5:38 “it get’s extremely hot whenever voltage runs trough it” voltage doesn’t run, current does

      -The igniter slowly melts the locations where it’s fixed to the hand, therefore slowly moving away from the flame eventually causing failure to ignite the flame or irregular ignition
      -Falling of his skateboard and breaking something or burning something in the tumble
      -Scaring the crap out of his parents and cause him some serious ear damage due to his dad/mom shouting at him not to do this any more

      Should I continue?

      I was very surprised to see at the end of the video some disclaimer…
      From 8:10 he mentions that he’s not (in no way) is going to promote someone doing this…
      Yeah right, well spoken, but did he even realize that he just put a video online with instructions how to build it. He knows that when he put the video online he has at least a public of 167.000 people… and statistically we know that not all viewers have the expected common sense or technical skills. And seriously, does he really thinks that nobody is going to mimic this? I’m even sure that he made this contraption to draw attention of his viewers and to gain an even larger public… Saying that you “not promote”blabla “in any way” is just a legal issue and has nothing to do with safety.

      People please be careful regarding your own safety and more importantly, with the safety of the people around you.

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