SpudFiles

Ok to start i have built several combustion cannons before with no problems. My boss approached me about building a cannon to take to shows (i sell after market lift kits for trucks, and we go to several big outdoor shows a year) to launch hats and t-shirts out of, distance needed is about 40-60 feet but i also want to use this for non-work related events. i plan on doing something somewhat simple over and under design. i have lots of spare things laying around basically just need advice. i;m going to use CO2, i have a 5lb tank with reg. ( need to know best way to attach to gun tank, got a sprinkler valve that i don't think can be modded so i'll be using batteries, also plan on air press gauge and blow off valve. what length tank and barrel should i shoot for. i was wanting something like barrel 36" and tank 24" what pressure would i need for the work related pressure? also whats the best method for attaching gauges, blow off valve, and co2 hook up?

@i_am_wood2381,

Welcome to SpudFiles.

Look around the Pneumatic Showcase and also look at Joel's t-shirt launchers over at spudtech.com: http://spudtech.com/detail.asp?id=49 .

You can connect the regulator's output to the tank via a quick connect or schrader. Make sure to set the regulator pressure to something reasonable and under the pipe's rated pressure.

I'd really consider getting a different sprinkler valve if you really think yours can't be modified. Having to use the solenoid seriously decreases power and increases weight and bulkiness (batteries, switch, wires).

As to barrel and chamber size... Figure out what size pipe a rolled-up T-shirt fits well in. I'd guess 2" or 2.5". I'd aim for about a 3 foot (36") barrel. Do the math to figure out how much volume that is... (2.5" x 36" = 176 cubic inches). You want a chamber at least that same volume, and 1.5x that volume if you want more power. So, for a 1.5x ratio, you want a chamber with at least 264 cubic inches. You could accomplish this with any combination of pipes... 21" of 4" pipe, 38" of 3" pipe, etc.... (Note, that's for a 1.5 : 1 ratio, you could use 1:1 without any problems I'm sure...).

Use all PVC sch40 or 80 NSF-PW rated pipe. Sch40 is just a wall thickness rating, NOT a pressure rating: the pipes need to say NSF-PW, not NSF-DWV to be pressure rated.
A 150-psi pop-off wouldn't be a bad idea, but is not required. A pressure gauge, however, is required (for accuracy and consistency).

As to pressure, I really can't tell you exactly how much pressure you'll need to launch a rolled-up T-shirt 60 ft. I'm guessing somewhere between 60 and 120 psi. Make sure not to exceed the pressure of the lowest-rated component in your system. If you use NSF-PW pipe, that will probably be your sprinkler valve, which should be rated to 125-150 psi.

Good luck.

Peace,
Pete Zaria.

thanks for the tips, i've go tall my pipe today (after a long search of three hardware stores, the 40 stuff is not easy to find in the right connections. need one stick of 2" for barrel and tank and i'm ready to mock up the gun.

some inspiration: http://www.aircannonsinc.com/cannons.htm

I don't agree with all the points Pete made.

1. You really should leave the pop-off valve in the design, especially if you use a fast opening valve. I would think that you might want to go to a fairly low pressure pop-off, perhaps only 60 or 70 PSI.

This gun will be used to fire towards people. If you duplicated Joel's gun you would have a gun that could do serious damage to a person.

2. I would go with a slower (and cheaper) valve like a 3/4" or 1" sprinkler valve. Unmodified would be fine (just need a little longer barrel). A blowgun trigger will get it to open faster, but again, you get into the power domain where you could hurt somebody.

If you are certain that you are the only one that will ever fire the gun then it would be reasonable to make a gun that is capable of hurting someone, it would be up to you to use it sensibly.

If anyone else will ever fire the gun then it is your responsibility that they can't take someone's head off if they fire it irresponsibly. They old "what if we put a couple rocks on top of the T-shirt and fire it Bob" scenario.

ya, this is quite off-topic but who do you work for? skyjacker, rancho,etc.? and does your company sell lift kits for 1987 suzuki smauris and 2003 ford rangers? oh and 1978 jeep cj7s? (duh i bet you do for the ranger)

I apologize if I bring this a bit off topic (or really off topic) But does anyone know how these t-shirt cannons work? Are they barrel sealing piston guns, or are they using a completely different method. Again, I apologize.

Well a t-shirt cannon can be anything really. You could use a modded sprinkler valve w/ blowgun trigger or you could use a ball valve, doesn't really matter. Heck, you could use a combustion if you wanted, it's just not a terribly good idea...

im not sure people want to catch flaming tee shirts paaiyan

jimmy hes not going to hurt anyone with a tee shirt unless there ~10...

just listen to pete he has everything you need for the gun...

and he isnt going to aim right at the person probably up above them...

spudthug wrote: jimmy hes not going to hurt anyone with a tee shirt unless there ~10...

just listen to pete he has everything you need for the gun...

and he isnt going to aim right at the person probably up above them...

Yes, a responsible person would have no problems safely using a high powered Tshirt launcher like Joel's.

But, it is always a good idea to try to make things fool-proof (of course, it's impossible to make it idiot-proof).

I would think that Joel's gun, with a rubber-banded t-shirt at a range of 10 or 20 feet could serious hurt a person.

And like I said earlier, with a projectile more dense than a Tshirt the risk goes way up.

In many venues a "gun" that has the potential to hurt someone would be banned outright. You may have to "take a round to the chest" to prove to the management that no matter what, the gun is safe to fire in a crowd.

UPDATE!!! Cannon is built and looks great pressure tested and have a slow leak someplace. I submerged it in soapy water and found nothing (i think from valve) test fired @ 40 psi with batteries and did fire but very low power, only paid 6 bucks for valve so i tried to mod it tonight and i think it's gonna work (have to let epoxy dry). I need a better regulator because mine only goes to 60lbs, where can i get one on the cheap need it to hook up to a 10lb CO2 tank? gun is loud and after three test fires had the police circling the block.

finally finished cannon tonight all painted valve mod works great (i can't believe the amount of power---at least 10x more) not a bad cannon for about 16 bucks still needs a barrel support. i'll get pics up soon