This instructable will show you how to assemble this basic air cannon. With the right air pressure, the right projectile (a small rock or piece of potato), and a little bit of luck, the air cannon can fire up to 200 ft! There are many different versions of this basic design, due to its simplicity. This air cannon should never be pumped to more than 40 psi, as it could explode with a dangerous amount of force.
The air cannon is basically just a pressure chamber that is pumped up with a bicycle pump and a valve separating the pressure chamber from the barrel. When a projectile like a small rock is placed in the barrel with some air in the pressure chamber, flick the valve quickly to allow the air to force the projectile out of the barrel with a loud whooshing sound!
ALWAYS USE CAUTION WHEN FIRING THE AIR CANNON! SERIOUSLY!!!
Here's what you'll need:
- about 2 ft of 2 in. wide PVC pipe for the pressure chamber
- two 2 in. end caps to seal off the pressure chamber (one for each end)
- a Schrader bike valve (Presta works too, but Schrader valves are more reliable)
- 2 ft of 0.5 in. wide pipe (you can make it wider for bigger projectiles, but I highly recommend using 0.5 in. pipe)
- a valve that fits a 0.5 in. pipe (I recommend getting your supplies at a local hardware store, as you can see how the pieces will fit together!)
- PVC glue and primer
- an afternoon
I should note that there are many ways to construct this air cannon, this might not be the most simple or straightforward way available, but you can easily modify this device to make it your own!
Step 1: Build End Caps
After you have gathered all of your supplies, and collected your thoughts, you need to start somewhere. This might be one of the hardest steps, be sure to revisit some of the pictures and look at other designs if you get confused!
Here we go!
Start by drilling a hole strait through the middle of one of the end caps to fit the Schrader valve, try to find a drill bit that makes the smallest possible hole to fit the valve, and use a drill press if possible! After your hole has been drilled, prime the inside of the hole with PVC primer and poke the valve through to make sure it fits. When you are absolutely certain you have done everything right, put PVC glue between the valve and the end cap hole so that it makes a tight seal. You want the end cap to be airtight!
Once you have done that, take your second end cap and cut a much larger hole in that to fit the 0.5 in. pipe. Be careful to make the hole exactly correct because you don't want it to leak! When you have cut the hole, cut about 5 in. of pipe off of the 0.5 in. wide piece of PVC. This piece will connect the pressure chamber to the dump valve. Glue the pipe to the end cap hole! You can breathe, it is all easy from here! (well...)
Step 2: Build the Pressure Chamber
Take a short break.
Alright, now we will finish up the pressure chamber and move on!
First, get the end cap that has the tube sticking out (not the bike valve one) and glue the dump valve to the end as shown in the pictures. Now you should have an end cap with a bike valve sticking out and an end cap with the red (or other colored) sticking out.
Glue the completed end caps to the 2 in. wide PVC pipe so it looks like the pressure chamber in the pictures.
You're almost done!
Step 3: Add the Barrel
You can make the barrel as long as you want, keeping in mind that with increased length, comes increased friction, and loss of power. :( If you make the barrel too short however, you lose accuracy.
Do not worry about gluing the barrel to the dump valve, as long as the barrel doesn't fall out. It is also much easier to load if you can detach the barrel.
With the barrel in place, you are done! Almost...
Just let the glue dry for a few minutes if you haven't already.
Step 4: BOOM
To load the air cannon, you will need a good projectile. Here are some of the things I have used:
- a small pebble or rock
- a piece of 0.5 in. dowel rod
- a chunk of potato
- multiple pieces of 0.5 in. dowel rod!
- a small marshmallow
Wrap your projectile loosely with a leaf or paper towel-like material for a good fit, and place in the barrel. It is important to give the projectile a good fit in the barrel, not allowing any air to escape without first pushing on the projectile. Attach a bike pump to the cannon and pump up the cannon to about 30-40 PSI. DO NOT EXCEED 50 PSI, AS IT MIGHT EXPLODE OR LEAK WITH A DANGEROUS AMOUNT OF FORCE
When you are ready, take aim and turn the valve as quickly as possible! Keep in mind that impact = mass times acceleration!
Step 5: Modify It!
This air cannon is designed to be easily modified, and the basic design is simple enough so that almost anyone can improve on it! I recently added a small attachment to the barrel of the cannon that would allow it to be mounted on a cheap camera tripod. You could easily modify to barrel to shoot smaller projectiles, or larger ones! This would be one heck of a pea shooter! Eventually I will make a much larger version of the air cannon, but until then, tell me what you did differently! I would love to see some of the things you decide to add or change! Leave a comment! I love receiving feedback!