Fuse making machine

This is a fuse making machine that operates nearly as well as a factory machine would. Have you figured out what exactly this is yet? It’s not an electrical fuse, it’s a Visco Fuse. Still not totally clear? Don’t worry, we had to look it up too. Visco Fuse is a high-quality safety fuse used in fireworks.

[Robert McMullen] built the machine as part of his degree in Mechanical Engineering at Olin College. But there’s a hobby twist behind its genesis. When he has free time he participates in Olin’s Fire Arts Club and we’re sure this stuff comes in handy. The fuse is made by encapsulating a stream of gunpowder in a tube of woven thread. Twenty spools of thread wrap their way around the nozzle of a fine funnel. Once the casing is in place the machine coats it in a waterproof lacquer.

The image above only shows the base of the machine. All the fun parts (and test burns including one underwater) can be seen in the video after the break.


  1. Alan Yates says:

    Very nice job!

  2. Ian Daniher says:

    Man, this thing was sitting in the WH1 hallway forever. Glad to see it’s up and running and churning out high-quality visco! Congrats, Ert!

  3. Chris C. says:

    Robert, may you always keep your fingers; so you can continue making cool stuff like this. ;)

  4. Mike says:

    At 0:40 I like the way he grabs the paper a split second before the spinning blades come down without loosing any fingers. Geeze man.

    • Mike says:

      Whoops – the above comment was on a video that showed up after the fuse making machine (very cool) my mistake.

      OSHA should check the fireworks making machine out :)

      • Brian says:

        Being as I did not see ANY English (or even a recognizable letter of the Latin alphabet), I am certain this factory is not within OSHA’s jurisdiction. But I think we all know what you were meaning.

  5. chicthomson says:

    I’ve built a few fuse blowing machines in my time, but that’s a different story for another time!

  6. WestfW says:

    The finished product is burning a lot faster than
    “Visco” is supposed to. It should be about 2s/inch, not 3in/s !

    • Brian says:

      He simply needs to adjust his powder mix. If he cannot find a slower burning smokeless powder, he could mix the powder with something inert (such as talc, or maybe a add additional carbon powder). The fuse itself (and the fuse making machine) works fine, he only needs to work on fine tuning the rate of burn.
      The only other comment I might add would be to replace the gravity fed funnel with some type of constant feed rate system. But assumeing that Robert isn’t planning to start produceing thousand foot spools, the funnel should work just fine. Actually, if this was my machine, I would add the constant feed rate setup ABOVE the funnel. That way, you could do several short batches (in batch mode), to check different powder mixes. When you have the mix you like, you mix and load the hopper, and away you go.

      No, this is an excellent build, and if I were making my own fireworks, I would DEFINATELY be looking into building one of these for myself.

      • webzijt says:

        Hi Brian. I’m aiming at using Robert his design to create the above mentioned 2s/inch burning fuse. From what I read in your comment I assume that you think this can be done with Robert’s design, without modifying the design? So the fuse doesn’t need to be thicker then this, for instance? I am also going to replace the constant cycle motor by a motor that changes in speed. Will the funnel then still be sufficient, or will variable motor speed then also create variable qualities of fuse? Any comments on my questions would be very welcome. Anne-Jan

    • alpha says:

      There is no set speed for visco. you can buy visco that burns anywhere from 2 – 30 seconds a foot

  7. nikescar1 says:

    Wow! Very nice job.

  8. Rahul Jain says:

    where can I purchase such a machine. I am interested in buying it….

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