RSSNeed to launch hot dogs, brats, and other stadium snacks into the upper bleachers at your local ballpark? Then build a Burrito Blaster with John Park. Based on the classic combustion-powered "spud gun" project, this cannon instead relies on an air power. Made with everyday objects like a sprinkler solenoid, PVC, and simple circuitry, this project is great for picnics, games, and other outside fun.
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seriously? duct tape? if the tank shatters, that stuff is going to make about as much difference as a tissue around a hand grenade. However, wrapping the tank IS a good idea, but to protect it from UV light, which degrades PVC, making it brittle. If you want shatter protection, try fiberglassing it.
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@chris... thanks for the tip, since you brought this up... a note that we have one our site and magazine...
http://makezine.com/warning/
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Right on, Chris, mind you I think the point of the duck tape was to prevent sharp shrapnel to hit to hit you rather than give the tank strength. And I think would do a good job at it, at 40 psi.
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"putting a thread into a hole" is called tapping a hole by the way...
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When pressurizing it too 40PSI, how many short bursts do you get or is it a one shot deal and then you have to hook it up to a compressor again?
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@Grant, your second guess is right-- it's a one shot deal. You will need to re-compress in between each shot.
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So I have two things. The first, I heard polythylene would be a better material to use instead PVC for the air chamber.
The second and most important. I have never done something like this before. How do I wire the trigger system. is it possible to refer me to a link with pictures. If not, could you dumb it down for me. I am not electronically inclined but I am very excited to get this thing going. thank you.
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@Jamie, We've heard polythylene is a better option over time too, however, duct taping the air chamber, using it above freezing temperatures, and keeping the psi below 50 will greatly reduce your chances of anything going wrong.
Take a look at the PDF for more details on wiring http://cachefly.oreilly.com/make/television/01/burritoblaster.pdf
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Hello fellow makers,
I just built a t-shirt cannon using this design for my school pep assemblies. I'm trying to come up with a design that can shoot multiple t-shirts with one pump of the tank. I had a multi-tank system with a ball valve for each tank, but system would be complicated to explain to officials who would use it. Anyone have ideas?
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check out the comments on this link for a wiring Jamie
chart http://www.instructables.com/id/Air_Cannon_1
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Anyone have the issue of not being able to open the electric sprinkler valve using 3 9V batteries wired in series? I hear the solenoid click but it doesn't fully open - I checked the ratings for the valve and it requires approx 0.3 Amps to open the valve. The 9V batteries from what I can tell have enough Voltage but NOT enough Amps.....any solutions out there?
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David, I've never had a problem like that, but it probably varies by valve. Sounds like you should confirm this by getting a regulated power supply (from an old laptop or other device) and testing it. If that's the case you may need to track down a beefier battery. Anyone have ideas on a circuit that could boost the current?
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John,
Hello, I saw the episode featuring this project as it re-aired on the local public carrier. As an engineer with experience in the construction of plastic pressure vessels, I'd like to raise a few issues:
1) Using the D.W.V. (drain, waste, vent) rated PVC reducers and clean-out fittings is rather dangerous. These fittings are intended for use in near atmospheric pressure applications only, the quality of these varies greatly from piece to piece, they do not have to meet any schedule test requirements. A better option would be to use schedule 40 or 80 pipe and fitting. The schedule rated parts must all meet certain minimum requirements for pressure and quality of fit.
2) The force exerted on the burrito is actually less than the force exerted on the clean-out and the reducer for that matter. The law governing this is simply (Force = Pressure * Area). The formula for area of a circular section involves squaring the diameter or radius, as such the 4" pipe fittings must withstand almost four times the force that the 2" burrito will see initially. Perhaps this is why the other t-shirt cannon uses several smaller diameter tanks.
3) The pipe compound used to seal the threads is an absolute 'No-No'. The solvents in this compound will attack the PVC and the internal parts of the valve. (read the precautions on the container). Teflon thread tape or a minimal amount of PVC glue are the only options for creating a leak free seal with PVC threads.
4.) The duct tape around the outside of the pressure tank is a good idea, it would keep the chunks together long enough for the air to discharge, at least in the case of a rupture due to hoop stress. However, having pressure tested several products with these types of fittings, I can tell you that the failure of this tank would not be due to hoop stress. The failure mode would be the end-cap blowing off or the reducer giving way due to axial stress. The real damage would be to the ear drums of the people nearby. It would be like having an M-80 go off within 10 feet of your ears.
I am not intending to discourage your efforts, I applaud the many great projects you've illustrated. The nature of this particular project is such that the makers should know the risks involved and have at least a basic idea of the forces at play.
Using the great free Frink calculator I've calculated this:
40 psi*(pi*((4.03 in)^2)/4) -> lbf
510.22292127686473 lbf
40 psi*(pi*((2.07 in)^2)/4) -> lbf
134.61410361366905046 lbf
So the plastic pressure tank is under more than 510 pounds of force axially. The burrito sees about 135 pounds of force when the valve is opened.
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