T-Shirt Cannon Question

[Carpe Spud]

I'm trying to build a low-power t-shirt cannon for a small school, powered by normal, 12g canisters of CO2. I'm thinking an over-under orientation, with a piston valve, or maybe a sprinkler valve. I have some experience with combustion and pneumatic spudguns, but I wonder if I'm in over my head. Also, I noticed Joel sells his guns for 500 some dollars, but from what I can tell, I could make one for less than 75 dollars, including labour. I guess some of the discrepency comes from his being full sized and he has to make money. So, my two questions are, is this going to be way too much, and am I miscalculating the cost somehow?

[Urban Ninja]

I built a similar launcher like that, It was over and under with a 4" chamber by 12" and uses a 1" sprinkler valve. I used a schrader valve to fill and all in all it cost me $50 AUS. I have numerous barrel sizes but that price I gave was only for the gun and one barrel. Oh and $5 for spray paint but hey thats nothing and Im still using those cans for my current launchers .

[Carpe Spud]

Alright, so my price estimate wasn't too far off then. The gun I'm building only needs to go 100 or so feet forward and so I'm looking at a 9" length of 2" piping for the chamber, and 12" inches for the barrel. I checked it out on GGDT, and it seemed ok, but I did use some shady numbers for the valve. What size barrel did you use to fit the t-shirts? I rolled up some shirts and I think that 2.5" might be a good size, but I was hoping someone knew the right size.

[Mihlrad]

im not too sure you are going to be able to get a T-Shirt 100 feet with only a 2" x 9" chamber...

For the barrel i personally would use a 3" pipe, i would use that for the chamber too but odds are that you will need to get fittings for the 3" online due to pressure ratings. I built a small cannon that had a 1 inch or 2 inch interchangeable barrel and about 12-14" 2 inch chamber i forget which one, and theres no way that could get a t-shirt even close to 100 feet (it can put a screwdriver halfway into a tree though)

So yea, your most likely going to require a bigger chamber to match the barrel size. Your total cost should be WAY under 100 dollars lets see

10" of 2 " pipe = 6-8 US for me
10" of 3" pipe = 14 US
10" of 1" pipe = 3 or so US

fittings = couple elbows, reducing bushings, couplings and male adapters = like 5-8 tops probably less for small sizes if you use 1" for connecting over and under.

Sprinkler valve = 11-18 , 11 for me it varies where you are though it seems.

Blowgun = 2-5 , and another 80 cents for the 1/4" nipple.

I put both 1 inch and 2 inch pipe because i wasnt sure if you wanted to connect the resevoir to the barrel and valve with 1 or 2 inch pipe, the 1 inch you only need the 1 inch pipe, the 2 inch you will require the 1 and 2 inch diameters because the valve will require 1" male adapters.

As for the CO2 setup you will need a gauge, and a new method that has been going around is to use a CO2 quick tire fill thing for a bike, it is controlled so it can be turned on and off when the time is right.

Here is an example of one of those

http://www.livingincomfort.com/blaico2tiin1.html

You need 16g CO2 for those though so it might not work out for you.

I also found a model such as this one that uses cheaper, 12g CO2 , i think it is compatible with the same ones used in like a BB or paintball gun which are way cheaper.

http://www.bikepro.com/products/pumps/suprflat.html


Good luck with your project, be sure to show us when your done ^^

[Carpe Spud]

Wow, thank you. I thought the specs seemed too small, but GGDT showed it being more than enough. I think that is from some the numbers I used for the valve. Thanks again, thats a huge help.

[Shrimphead]

I would suggest that you make a decent sized gun with a good c:b ratio. When you are going to use it for shooting t-shirts, you only have to pump it up to like 50 psi which you could probably do with a bike pump, then you can pump it higher for when you want to shoot for power.