Self Contained Pneumatic T-Shirt Cannon

Two weeks ago I came across instructions for a T-shirt Cannon in Popular Mechanics and decided to build it. Of course along the way I thought of suitable enhancements. Instead of using a bike pump to charge it I wanted to attach a tire pump and a power source so that I could pillage cord free!

WARNING: This should go without saying but this can be dangerous! Do Not Shoot at people or pets. When testing for the first time do not start with a high pressure, start with a low amount and slowly increase!!!

I will add many more pictures very soon, I dont have access to my digital camera atm.

Step 1 Gather Materials

There are three distinct sections so I will group the materials in those parts.
First: The Cannon itself
1x - 2 Ft of 4 Inch PVC Pipe
1x - 4 Inch diameter PVC End Cap
1x - 4 Inch to 1 Inch diameter adapater ( I substituted a 4 Inch to 2 Inch adapter and a 2 Inch to 1 Inch adapter)
1x - 2 Ft of 1 Inch PVC Pipe
2x - 1 Inch Male threaded adapter (to screw into the sprinkler valve)
1x - 1 Inch diameter Automatic Sprinlker Valve
1x - 1 Inch to 2 Inch adapter
1x - 3 Ft of 2 Inch diameter PVC Pipe

1x - Presta style Bicycle inner tube
1x - Presta to Schrader valve adapter ( I found mine at a local bicycle shop )

Second: The Air Pump and Electrical System
1x - Portable 12v Tire Pump
1x - Battery operated Electrical Drill ( This is only used for the batteries )
1x - Main power switch
1x - Normally off push button
1x - Electronic parts enclosure
1x - Nerf Gun ( I used this for the handle, Optional)
1x - Normally Off push button trigger switch

Third: Misc
2x - Clear Silicone Sealant
1x - Gorilla Glue Epoxy
1x - PVC Glue and Primer
1x - Package of Large Zip Ties
1x - Package of Medium Zip Ties

Comments

[ilpug]

This is awesome, but i cannot give it my seal of approval because you used an ABS pressure chamber. Good ideas.

[Meico]

What is the downside of the ABS pressure chamber? I was unable to find any reference to its pressure rating and I assume that is what you are implying. I would appreciate your input if you have any to offer. Also, nice pun.

[ilpug]

There was a pun?


ugh, i am so terrible at spotting them.

anyway, ABS is not rated for higher pressures. As a general rule, PVC is better for sustained pressurization than ABS. However, PVC is more brittle, and shatters like glass when it fails. ABS just tears like paper and tends to stay together more.

At higher pipe diameters, the pressure rating of pipe radically decreases. Four inch PVC pipe is rather hard to find, but it is probably worth it. If I were you, i would replace the chamber with a 3 inch U-shaped PVC chamber to hold higher pressures more safely in the same volume. Also, for unmatched safety and pressure ratings, i would use a metal chamber like an old fire extinguisher.

I noticed that you glued PVC to ABS in a pressurized joint. This is a major No-no, and should be fixed very soon. Also, keep in mind that the actual sprinkler valve itself has a limited pressure rating, and i would not trust it over about 80 PSI.

This is a very nice gun, and despite my paranoid ranting there is little chance it is going to blow up in your face at medium pressures. However, if you plan to boost the pressure and power, you really would want to consider upgrading your fittings and chamber.

-Ilpug.

[Meico]

Oh, I thought the bit about giving a 'seal of approval' on a pressure chamber was a pun...

Thank you very much for the information though. I was unable to find much information on this matter. Eventually ill replace this whole gun with a new design for higher pressure. My gut feeling for max pressure is 60 psi. At 55 psi it shoots about 120 ft.

I really appreciate the comment, thanks again!

[ilpug]

just keep safety in mind and have fun!

[stevemoseley]

Great idea. The fun factor barely outweighs the danger factor.

[polaris 250]

nice gun, i made a cannon that shoots potatoes 250 yards

[stevemoseley]

Great project. My son has asked me to build him something like this so I can shoot hot dogs and t-shirts to him across the back yard like they do at the local baseball games.

[mgreening]

Instead of all the tire valve parts, just drill a hole in one of the endcaps and insert a rubber automotive tire valve like these.
I built a water/pnumatic 2 liter bottle launcher this way and it works great

[Meico]

I wanted to go with those but they cant handle how thick the walls of the PVC pipe. They only work with materials that are 1 -2 mm thick.

[luv4paintball]

Edit: Try looking for something similar to this

[luv4paintball]

Go to your local Auto Parts store, they have tire valves like that however instead of being rubber, they are a metal and come in two main parts. You stick the main valve assembly in from the inside and then screw a nut down over the top from the outside.