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The good folks at Twin Cities Public Television shipped the Burrito Blaster to my house so I could take it on some demos. I was glad to get my hands on it again; part of the fun with this type of project is the endless fiddling and improving you can do. Plus, my kids like shooting socks out of it.

When it arrived, I noticed that the trigger box was smashed in a bit during transit, so I decided to rebuild it in a sturdier enclosure. I got a small, cast-aluminum project box, drilled it out for the solenoid wires, safety, and trigger. I then re-wired and re-soldered it all, adding a braided sleeve for the external wires. I also mounted the switches on top so that the whole thing can be rested on the box; with the old design there was never a convenient way to set it down.

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I also added a cutoff valve to prevent the chamber from being filled beyond 65psi. When I went on Attack of the Show! we didn’t trust the gauge on the air compressor, so we were filling it by count. Probably why one of the guys on the firing line got the wind knocked out of him. Hope this helps next time.

Future mods planned: a real PSI gauge, a sling for carrying, and some LEDs to indicate “Safe” vs. “Armed”. I suppose I should fix the slow leak coming from the rear cap while I’m at it.


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Comments

  1. Make: television says:

    I enclosed that trigger box in at least two layers of the sturdiest bubble wrap I could find, I promise!

    Then again, what kind of a world do we live in if you can’t count on a little harmless in-transit component smashing as a source for modding inspiration? I regret nothing.

  2. Kent KB says:

    Nice to see this is evolving, sometime mishaps (like shipping) can refine a good idea and make it even better, I like to call it “Lemonade”
    The “Attack of the Show” guys looked very nervous indeed!
    Keep up the Good Work Buddy, and see you a Maker Faire SF.4 I hope.

  3. John Park says:

    (OK, I never liked that big, flimsy enclosure, Joel, so maybe I helped it along…Don’t tell Bill Gurstelle)
    Kent, that’s a good point. I’d probably make sturdier designs if I had to immediately ship them to myself.

  4. Lasrin says:

    Where can we get the stats on that pressure relief valve? I’ve been looking for something like it for an ongoing project. Where???

  5. John Park says:

    Lasrin, I don’t have info on them, I just picked up two for $1 at the electronics store. They had them in a couple of other values, too. To be honest, they seem a bit on the cheap side to be that precise. Anyone know more about these or a higher quality alternative?

  6. observer says:

    Perhaps I looked incorrectly, but did I see any duct tape? I don’t think. That stuff is crucial so if your chamber explodes, you’re not impaled with tiny PVC shards. 3 dollar roll vs shrapnel lacerated body?

  7. John Park says:

    We were given this same warning to tape the chamber, so we did that on the TV show. Since then, I’ve read a lot of comments here and on Instructables about duct tape doing nothing to stop exploding PVC. Does anyone have firsthand experience of the duct tape helping?

  8. Bob D says:

    Don’t use PVC for the compressed air chamber. Use polyethylene, it shreds and doesn’t fragment. We use poly tubes for shooting aerial fireworks shells for exactly this reason. I’ve been within 5 feet of a 6″ shell detonating in a tube (it got put in upside down so the lift charge did nothing) and was uninjured. The poly tube bulged quite a bit, and blew out the bottom, but did not fragment.

    A PVC pipe being filled with an unknown pressure of compressed air can quickly turn into a bomb.

    -Bob