Airsoft or Paintball Home Made Pneumatic Trigger Air Cannon

This is for those who play airsoft or paintball and need an anti tank or anti bunker cannon. This is easy to do, and can be made in one afternoon. 

You will need:
(All Schedule 40 Rated PVC)
x1  2" Diameter by 2' Length PVC Pipe
x1  1" Diameter by 2' Length PVC Pipe
x1  2" PVC End Cap (Rounded)

x2  1" Threaded PVC Connector
x2  2" PVC Schedule 40 PVC Coupling (Long)
x2  2" to 1" PVC Reducer Bushing

x4  2" PVC DWV Coupling (Short)

For the best results with a pneumatic trigger launcher, use a Rainbird 1" inline solenoid.

Items you will need:

x1  1/4" to 1/4" Male Male Brass Nipple
x1  1/4" Air Blow Gun Trigger
x1  Tire Valves (Found at Auto Parts Stores)

Tools you will need:

Power Drill
5/8" Hole Drill bit
7/16" or 15/32" Hole Drill bit (1/2" is too big)
Phillips Head Screw Driver bit
Teflon Tape
Epoxy (Gorilla brand epoxy is best)
Duct Tape
PVC Primer and PVC Glue
A Saw of some kind (skill saw recommended) 

Cut the 2" PVC pipe about 1/3 of the way, so you will have an 8" piece and a 16" piece

This is where you can choose. One piece is your barrel and the other is your air chamber. You can cut it evenly if you wish, or have a short chamber and a long barrel. We have found a shorter barrel and a longer chamber works the best.

Cut 2 pieces of the 1" PVC pipe about or slightly shorter than 2"

Use the 5/8" hole drill bit and drill a hole in the end cap. This is for the tire valve.

Unscrew the top part of the Rainbird. Remove the spring from the rubber diaphragm. Remove the solenoid and the bleed valve. Use the 7/16" hole drill and drill a hole in the middle of the top portion. Screw in the brass nipple (it is a very tight fit, you have to use a lot of force to get it threaded in the hole).

Note: If you want a safety so that you can run with the launcher on your back or something, put a 1/4" ball valve into the lid rather than the brass nipple. The last picture shows a comparison between the standard set up (on the right) and the assembly with the safety (on the left, the red lever is the ball valve).

Use PVC primer and prime all the parts that will be connecting (see images for where to prime what parts).

Use epoxy and put a generous amount of epoxy around the tire valve inside the end cap. Be sure not to cover the air hole
Also put a generous amount on the outside for added support and protection. Do not skimp on the epoxy. If you don't put enough epoxy around the valve, it will leak, and you will have to start over. 

Put epoxy on the tiny holes on the inside of the lid. Also put epoxy in a tiny hole in the exit of the bottom half (see red circles for placement).

Put epoxy all along the rim of the brass on the inside and out for extra leakage coverage. Again, if you do not put enough epoxy around the brass, it will leak and you will have to start over. 

Take the PVC glue and generously apply to both areas of the parts that will be connecting. Be careful, the glue will dry quickly. 

Connect the 2" to 1" reducer to the schedule 40 (long) 2" coupling.

Connect the 1" PVC small section to the 1" threaded coupling.

Connect the above pieces together.

Repeat 1 more time with the other identical parts.

Connect the 2" PVC pipe sections to the schedule 40 (long) couplings.

Glue the tire valve end cap to the end of your chamber.

Let dry.

Put the Rainbird back together. Be sure that you place the rubber diaphragm back in the correct orientation. Be sure to put teflon tape along the threads of the chamber and barrel. Also put Teflon tape on the threads of the brass fitting. 

Screw in the air trigger. (I cut my air trigger in half so that it will not stick so far down)

There are many different triggers you can use. The one on the left has a 1/4" Ball valve for a safety, the one on the right does not have a safety.

Use the 2" PVC DWV Coupling (Short) and tape or glue them on the end cap and the end of the barrel. Glue or tape the remaining 2 couplings to the Schedule 40 2" Couplings to give it more of a "Rocket Launcher" appearance. 

Make sure you screw the chamber and barrel into the correct sides of the Rainbird. The chamber goes on the back end and the barrel goes on the front end. There are arrows on the Rainbird that show the direction of the airflow.

Once all the glue is cured (let sit over night), pump it up with a bike pump or air compressor. 

We have found that 80 PSI works the best, any more pressure and the projectiles launched start going wild.

Ammo that can be used:

Nerf Mini Vortex Pocket Footballs
2.25" Stress Balls

Once you have assembled it and let it cure, pump up the chamber to about 40 PSI and place the launcher in a bathtub full of water to check for leaks. If you see any bubbles, you missed a seal and need to start over.

Once you have checked your seals, just paint it what ever color scheme you want and you are ready to go!