Instructables

How To Build a Generic Air Cannon

Air cannons. Fun for the whole family. Shoots anything, really. Bottles of water for the kids, bottles of liquor for dad, kitchen utensils for mom, food for the dog, the dog (Kidding), stuffed animals for the little tykes..... Good fun. You can also shoot nets, grappling hooks, bricks, smaller air cannons, dumpsters (if they'll fit in the barrel), your mother's china, lit fireworks, and politicians. They are mainly used to shoot projectiles like balls (tennis or golf balls), potatoes, and my personal favorite-water balloons (filled with the liquid of your choice!). The whole point is this-you NEED one of these babies. And you need it NOW. Of course, I'm aware that this isn't the first air cannon instructable on here, and it won't be the last. But I hope that it's helpful, inspiring, and if nothing else I hope it's at least humorous.

Before we begin, there is a point I would like to stress- and that is Stupid hurts. You are building an air cannon (this could be used as a weapon). Because this cannon will belong to you, and it is your cannon, if you decide to do anything..................well, stupid with it, it's also your stupid. So it is your cannon, your responsibility, and anything you do with this thing is your consequence! That being said, END DISCLAIMER, BEGIN INSTRUCTABLE!!!!!!!!

In case you don't know how these amazing devices work, well obviously they use air (DUH-air cannon). Air is pumped and compressed into a chamber on one end of the gun, and on the other the ammunition is stuffed into the barrel. The barrel is connected to the pressure chamber via a ball valve or an electric solenoid valve. The valve lets the all the compressed air flow from the pressure chamber to the barrel, pushing the projectile out of the barrel and into the next county.
 
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DanTDM2 months ago

seal leaks with epoxy

-copper tube-3 months ago

bell reducers are not pressure rated

I pump my air cannon up to 110 psi and I can't seem to get it to shoot very far at all, the leaks are sealed, but it doesn't want to fire far at all, any suggestions?
eyebot117 (author)  Philisawesome2 years ago
Try using more wadding behind the projectile. It will create a better seal for the air pressure to push against getting more power out of the shot.
also check out my air cannon im gonna post a new one in a week or 2
dont use as much psi because if the seal on the projectile isnt right then maybe 40 - 50 psi would be better
Would a longer pressure chamber somehow be better? Perhaps allow for multiple shots on each charge?
Beybladera2 years ago
Is the ball valve easy to turn? I want to make an air cannon that is stationary on the ground like a mortar that is set at a 45 degree angle for max distance, but I also want to be able to trigger the firing mechanism (turn the valve) from a distance. Do you think it would be possible to attach a thin rope to the trigger and pull that to fire, or is the valve handle too hard to turn from a rope?
eyebot117 (author)  Beybladera1 year ago
It is difficult to open and close. Even if lubricated, it takes a little bit of force to break the valve and release the pressure for the shot. However slow the opening may be, the airflow couldn't be much straighter. A solenoid valve, which requires an electrical current to open is an alternative option that is used in most air cannons nowadays. Used in sprinkler irrigation systems for lawns, this type of valve opens MUCH faster from the push of a button, however the airflow is not very direct and may affect the shot.
godoggie2 years ago
Oh and by the way, 5 stars buddy this is an awesome instructable!
godoggie2 years ago
I would like to hear the commentariat's point-of-view on the pros and cons of PVC and or metal pressure chambers.

http://www.instructables.com/id/NASH-Air-Gun/ 

Also, how many of you guys have an air cannon yourselves? I'm always curious ;-) And what have you used for ammo? I'm thinking about making an 'ible for paper rockets, as they're pretty fun to shoot and work great for airsoft wars...
cj86752 years ago
http://www.instructables.com/id/micro-black-powder-cannon/
sebasr963 years ago
Nice!!!
Few questions:
Will a 1/2" ball valve work properly (lever ball valve)?
Isnt the valve too hard to open when firing?
eyebot117 (author)  sebasr963 years ago
Yes and no. You can use whatever size valve you wish. I lubricated my valve so that it would be easier to open, so no it's not hard to open/close at all.
What do you use/recommend for ball-valve lubrication?
eyebot117 (author)  thedave4132 years ago
WD-40 for a metal ball valve, silicone for PVC. :)
polaris 2502 years ago
Got one that shoots 250 yards
Your "disclaimer" needs beefing up.   I would like to suggest that all high pressure air cannon instructables should include a warning such as:

"These air weapons can shoot things fast enough to cause severe injuries or death. Never use them to shoot things at people."
tred112 years ago
love the commentary, pretty hilarious :P
X3R01172 years ago
Couldn't you wrap the pressure chamber in duct tape so that 1. air doesn't escape as easily and 2. even if the chamber does explode, the duct tape would take most of the force.
eyebot117 (author)  X3R01172 years ago
Of course. However I'm not positive that will prevent the air from escaping. Unfortunately, duct tape will not take most of the force from a rupturing pressure chamber. For one, the chamber would have to be under immense pressure for it to rupture to begin with (we're talking 200 psi-ish, but it depends on the size of the pressure chamber), which should it explode-the duct tape may only help prevent a certain amount of shrapnel from peppering your body. The pressure chamber would still explode nonetheless.
I have seen people wrap their pressure chambers in chicken wire/wire mesh for the sole purpose of containing shrapnel, but again-pressure chambers are DANGEROUS!!!!

That being said- NEVER over-pressurize your pressure chamber, ALWAYS treat the pressure chamber with extreme care (as you would any firearm) when under pressure, and ALWAYS use schedule-40 Pressure-rated PVC pipe when building PVC pressure chambers. It's also never a good idea to leave it under pressure when not it use as this can weaken the chamber as does cold temperatures.

However, the tape always gives things a nice look anyways and there's no harm in wrapping your pressure chamber in duct tape.
Would there be someway of making the ballvalve assembly able to screw on and off to change between types of "combustion" chambers?
eyebot117 (author)  forgelearner12342 years ago
Sure. Just use threaded adapters. That's what I used here! Basically, the pressure chamber, the ball valve, and the barrel can all be separated and interchanged with other parts.
red2113 years ago
do you use a bike pump or air compressor
eyebot117 (author)  red2113 years ago
Air compressor. Bike pump would also work I suppose... Have fun pumping it once the PSI in the chamber hits 80 though.
red211 red2113 years ago
k
Wowzers! this is exactly what i was looking for! I have been looking for a plan for building one of these things, but all of them ( except this one and a couple of other ones) require money, and i dont feel like paying anyone money. I intend to use your design, just with the pressure chamber larger and bent underneath the barrel so that it is more compact. I'll probably post it on instructables, so keep an eye out!
eyebot117 (author)  zanethebrain3 years ago
Sounds good. Remember:over-under cannons are compact, and still very good, but when you curve pipe you lose a little power due to weaker airflow. But to compensate, just pump it up more!
technoguy943 years ago
Say...If you packed it right so it was sealed, could you shoot water out of it? I mean pure water, not in a balloon or a bottle or anything.
eyebot117 (author)  technoguy943 years ago
Sure. Any liquid, actually. Salt water, urine, blood, vanilla extract, olive oil, crude oil, paint, you name it. Just aim the cannon at an inclination so that the liquid completely covers the ball valve. This will push the liquid out better.
XOIIO3 years ago
How many PSI can you fit in?
eyebot117 (author)  XOIIO3 years ago
I can only get to 90 psi right now, but after I seal the leak (between my bushing and my ball valve), I'll be able to hold more. My target pressure is 100-110 psi.
how much does it cost
eyebot117 (author)  JaronNeumann3 years ago
Some of the stuff was given to me by a buddy, but the fittings cost me under $30. The barrel could probably be purchased for $10-$20, and the valve will cost probably $20-$30. The smaller the valve, the cheaper they are.
Purple Guy3 years ago
I dont have anything to say just no-one had commented on this before so i felt sorry for you :)
Very Nice!
michaelg344 years ago
 i was thinking of making one of these only using a 2'' barrel, how long was your barrel and how long was the total cannon?
eyebot117 (author)  michaelg344 years ago
The whole thing was approximately 5 feet long, and the barrel length was about 3 of those feet.
okay, thank you
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