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So my friend is DJing a party on New Years and I've been commisioned to build a confetti cannon for the event. What I want is a twin barrel system that fires one shot from each side of the dj booth, and both barrels are powered by a single large pressure chamber. A high confetti capacity and launch height would be nice as well, since we'll be in a hotel ballroom.
I'm thinking it's going two have two 4 inch barells and a 6 inch pressure chamber. I plan on using an unmodified rainbird valve so it can be fired with a button and I have one laying around.
Since not alot of pressure is needed to launch the confetti, my first thought was to hook the two barrels up to the chamber using pressure tubing. However, I'm worried that the tubing will be too restrictive.
Hooking the barrels up with PVC is not very practical, however. I have no idea where the barrels will be positioned or how far apart they'll be. The only way this would be practical would be if I mounted the cannon in the air on a big 2x4 stand.
So what are your thoughts on the design?
Will pressure tubing provide a sufficient volume of air to launch the confetti?
Oh, and I also planned on using a large bike pump to pressurize the chamber, as it only needs to be done once and i dont want to lug around a compressor. How hard will it be to pump up, lets say, a 3 ft long chamber made out of 6" PVC to a sufficient pressure?
Thanks for your time, looking forward to hearing from some more expierianced cannon builders.
PS, I've attatched rough pictures of my two proposed designs
The tubing would be very restrictive and probably launch confetti about 2 feet. I would go with your first design. For your pump I would say you could do it, just make sure everything is airtight.
Hey Plinker, What safety mechanism's have you got in place to prevent innocent bystanders being hit by confetti traveling at approx 200 fps?
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I don't think the tubing will give the desired results. You could always purchase another valve then place the chamber in between the two barrels, and having both valves on the same circuit to trigger simultaneously.
c19o - That's kinda what I figured would happen, especially if I go with two 4" barrels
Novacastrian - Well first of all, they'll be next to the DJ booth, which will be sectioned off with caution tape. I'll also wait untill about 10 minutes to midnight to pump it up, and leave the wire leads disconnected until ready to fire.
hubb017 - I'm not too worried about the orientation of the valves and the piping. With two valves, I would be worried that an inconsistency in the opening would cause one of the shots to be a dud. Also, If I had two valves I'd just forget all this routing garbage and hook a chamber up to each barrel... Now that I think about it... Thats starting to seem like a much more atractive option. I'm going for parts on tuesday so I'll check to see what i can get a rainbird for.
I forgot to mention that economy is a big thing here, since my freind isn't paying for it and this isn't going to recieve much use. I'd love to hook up some piston valves and just run the tubing to an exhaust, but that's too time consuming and is probably overkill for some confetti.
Keep the ideas and suggestions coming, it's a great help
If that is the case, make it all so that it can be dissembled. That way, when it's done, you can make a truly remarkable launcher.
I agree, stay away from the tubing. Even one inch fuel line is going to be very constricting for a four inch barrel.
Rainbirds or any valve aren't going to cost a lot. And they are handy to have around anyway. I would get a second valve and build two identical launchers. Then they could be fired simultaneously or at different times.
I haven't had very good luck with confetti in the past. Build it early so you can test it. I had to use a huge sabot behind the confetti to make it fly right otherwise it just made a mess within 2-3 feet of the launcher, I assume you want it to shoot over the dance floor so a good 20-30 feet.
And I would be leary of leaving those things pumped up for a long time near those big DJ speakers. 6 inch pipe is weaker than smaller pipe and won't hold the pressure smaller pipe will either. The vibration and whatnot could cause problems. Something to think about.
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I have pumped up a leaky 10 gallon air compressor chamber to 80 psi with a leaky bike pump, so it certainly will be possible.
If you are using two 4 inch barrels, I would suggest either using a valve with much higher flow. A far better idea would be to simply use two small air chambers, one connected to each barrel with separate valves. You could attach the two with a hose to pressurise them simultaneously, and hook up the two solenoids to the same switch.
If this is being used near any innocent bystanders, the use of PVC may not be a good idea. Because of its nature, even pressure rated PVC pipe can have small but dangerous defects, which several members of this site can attest to. A very small risk, but the people who have had shards of PVC imbedded in their limbs can tell you that it probably isn't worth taking.
If you do this, build it carefully, handle it carefully, use low pressure, and don't charge it until you need to.
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Now that I've considered all the options, I've come up with yet another
I've always wanted to make one of the classic spudzooka designs, the coaxial with the gasket rubber and sheet metal diaphram. Since the firing mechanism on the spudzooka is significantly better than a rainbird, I could fire the cannon at a lower pressure which would make the setup much more safe. Also, it would be relatively cheap too make two of them, since the design is pretty simplistic.
And best of all, instead of having two worthless confetti guns after the show, I would two spudzookas
The biggest downfall I see is that the barrel capacity would be significantly reduced. I can't imagine this being too big of a problem, especially if I make the barrels long, stuff em high, and use a good sabot.
So that's my latest idea, any thoughts?
I doubt it's worth bothering with sabot really, just make sure the valve is sealed then pack the confetti in tight.
I think a sabot of some type will be required. Just packing the confetti into the barrel is going to give a cloud of confetti that'll only fly a few feet. There just isn't enough mass in an individual piece of confetti (relative to it's surface area) for it to carry very far.
I would just use two disposable paper or plastic cups. Insert the first cup with the open end towards the valve to seal the barrel. Insert the second cup, filled with confetti, with the open end towards the muzzle.
I believe disposable cups fit pretty well in 3" pipe. Getting a sabot for 4" pipe migh be kind of hard.
The sabot would need slits cut into it to open up on leaving muzzle however, otherwise all you'll have is a cup full of confetti hitting the ceiling...
Nope, you don't need to modify the cup (sabot) with slits (though you may have to shorten the length of the cup to get it to fit the barrel ID).
Air drag will pull the cup off the confetti, or the cup will tumble and dump the confetti. A cup full of confetti that is a couple inches long and 3 or 4 inches in diameter but has a total weight of only a couple grams is hardly an aerodynamic projectile.
I think the big challenge is getting the cup to not dump the confetti too soon, the same problem that just packing the confetti in the barrel has.
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