This is my first instructable.
I have made an air cannon that fires projectiles ( AA cells) up to about 60 meters. It is powered by air pressurized with a bicycle pump.
The overall cost of the project was very low, about Indian Rupees 200 ( US $ 4) not including the bicycle pump.
The bill of material is a s follows :
1. 70 cm x 15 mm diameter ( inner ) of UPVC pipe
2. 30 cm x 15 mm diameter UPVC pipe
3 15 cm x 15 mm diameter UPVC pipe
4. 12 cm x 15 mm diameter UPVC pipe
5. 2 pieces of UPVC L section (15 mm)
6. Ball Valve as tap
7. End stopper
8. Bicycle valve
9. Araldite or some other resin
10. Bicycle pump
Other basic tools
Step 1: Basic Assembly
Assemble as follows:
i. Attach the 70 cm pipe to the ball valve.
ii. Connect the 12 cm pipe to the other side of the ball valve.
iii. Connect the L-piece to the 12 cm pipe
iv. Connect the 15 cm pipe to the L-piece
v. Join the other L-piece to the other end of the 15 cm pipe
vi. Join the 30 cm pipe to the L-piece
All these connections in my cannon are quite rigid. Hence I did not use any sealant for these joins. But the sealant is quite cheap (Indian Rupees 50 or about a dollar or so). So, this part is up to you. If you think your joins are weak and will not be able to hold the air pressure apply the sealant.
Keep this assemble aside for the time being
The araldite was however used to fix the valve.
Step 2: The Stopper and Valve
Now for the important part. I won't say difficult, but you have to be meticulous or the air will escape.
Take the stopper and the bicycle valve.
Drill a hole through the middle of the stopper, such that the valve should snugly fit inside the hole.
( My experience is that taking a large nail, heating it and melting through the PVC is much easier. I used this technique as I didn't have a drilling machine !! )
Now insert the valve such that the air inlet is to the outside. Now this fix is in no way going to be airtight!! So, use a good quality resin, araldite id the preferred choice even if it takes long hours to set.
Step 3: Final Addition
Attach the modified stopper to the 30 cm pipe from the earlier assembly.
Step 4: Working
1. First close the Ball Valve (tap)
2. Pump in air through the modified stopper (with valve) using the bicycle pump.
3. Pump until the pressure reaches about 5 PSI.
4 Drop the AA battery down the open end of the 70 cm long pipe.
CAUTION CAUTION :: This system is a potential weapon. If aimed at internal organs, sensitive places, a human being can DIE. Even if aimed at limbs, heavy injury can be caused.
5. Aim AWAY from people, animals, etc. and out into the open.
6 Open the Ball Valve to release pressure and let the battery flying onto the sky.