End-Around Pneumatic Cannon

While not particularly new or creative, here are my plans for a simple pneumatic (compressed-air powered) potato cannon. It can also be used for other projectiles, as long as they fit down one of the interchangeable barrels. It uses an electrically operated valve, originally made for in-ground irrigation systems.

This project is also documented on my website at: http://www.mbeckler.org/pneumatic_cannon.php

Step 1 Safety Warning!

Safety Warning: Please be careful with this project. From what I've heard, PVC is not meant for holding compressed gasses. Gasses compress much easier than liquids, so be careful. The sprinkler valve used is designed for cold water, so be careful. The pressure gauge is designed for cold water applications, so be careful. Almost nothing in this project is used in its intended purpose, so please be extra careful. If you explode one of your PVC pipes, you will have essentially detonated a pipe bomb, and you are going to be in a world of hurt. You might want to take an old pair of jeans, cut off one leg, and wrap it around your pressure chamber. You can also use an old towel, or some metal screening. It probably wont help in the event of a pipe rupture, as one user has suggested. He also reminds us that some PVC is not actual PVC through the entire wall of the pipe. He says that 'cellular core' pipe, which is not rated for pressure, has a lightweight foam core, surrounded by thin layers of actual PVC. Please double check your pipe before purchasing, to ensure that you are not purchasing cellular foam core pipe. Another user has written that fiberglass mesh tape, used in construction for drywall joining, might be a stronger pressure chamber coating. Another user suggested taking coupling, sanding off the inner stops, and gluing them to the outside of your pressure chamber.

If you only remember one thing from all my safety warnings, remember this: PVC shrapnel will not show up on an X-Ray. The doctors will have an extremely hard time picking all the plastic shards out of your body if something goes wrong. You have been warned.

organicengines adds a helpful reminder to keep your PVC out of direct sunlight, because the light will degrade the plastic and make it brittle. Be careful!

Yes, this could be a dangerous project. I'm not a lawyer, but I'd like to say that I'm absolving myself of all responsibility for your actions. If you decided to build one of these cannons, by all means have fun, but please be safe. I'm not responsible for anything except for fun. If any of the Instructables administrators or moderators feel this project is too dangerous for this website, I will gladly remove it as soon as possible.

Another safety point: This is a cannon, which is a type of gun. Guns are meant to be dangerous, they would be pointless if they weren't. If you have no experience handling guns, please be very careful with this project, and do yourself a favor and take a firearms safety course. It will be a good experience even if you never shoot a gun again. If you have experience with guns, please be careful regardless. When I went through hunter's safety, they taught us three important rules of firearms safety:
1. Treat every gun as if it is loaded, so always point it in a safe direction. This means not at you, your dog, or anybody standing around. Point it up in the air, or down at the ground.
2. Always keep your finger off the trigger (valve switch) until ready to fire. Enough said.
3. Know your target and what's beyond. Plywood, fences, and garage walls are not strong enough to stop some of the things you can shoot with this cannon. I've put clean holes through both walls of an empty 55 gallon steel drum, so know what's behind your target. Try to not shoot this cannon in residential areas, or use really low pressures and soft projectiles. Soft projectiles include rolled-up, wet socks (more on this later), water, and loose snow.

That being said, this cannon can provide hours of entertainment, as well as a bit of education, in projectile physics and the ideal gas law.

Comments

[Pizzapie500]

What if your solenoid runs on AC?

[jj.inc]

It should still work, just fine, I can imagine how it could anyway. Hook it to a 9v battery and see what it does. (It can't hurt it)

[Pizzapie500]

Dang it! The solenoid blew up! JK! Yeah it works, it makes that clicky noise.

[jj.inc]

Good, you actually got me there. Yea, do you have a sprinkler system that uses these which plugs into your outdoor AC, if so then that control box actually adapts the power to lower voltage DC. That may lead to the belief that it is an AC valve, or I don't know what I'm talking about.

[kve23]

some kinds of pvc are not for pressure but others are designed for pressure

[ghoru]

Coolest sound ever! lol cant wait to build one...or 2...ah hell go for 3 how big are paint balls... :D

[seltzer10]

paintballs come in different sizes but the best to easily fit is the .50" paintballs

[tomtortoise]

3/4 inch pvc barrel

[ghoru]

hmm... wonder how a 3 barrel separate trigger system would go....?

[paul1256]

dose the size of the air chamber matter

[clemsonguy1125]

YOu used a dwv reduser, this means its not pressure rated a can explode 

[matthewbeckler]

Thank you for your comment. This is a very real and serious concern, and has been mentioned at least once in my writeup above. I have never had problems with my DWV reducer, but in future designs I will only use pressure-rated fittings as I mentioned in step 2. Thanks for your concern.

[clemsonguy1125]

 ok sorry I just noticed it in the intro, also you may not want to shoot it in the snow because pvc becomes brittle, for more info you can check www.spudfiles.com

[knuckel]

mine is like yours but HUGE

[lew0004]

I was wondering if you should make a picture of a End-Around Pneumatic Cannon except with a 3 barrl

[matthewbeckler]

Part of the design restrictions that come with using the U-shaped valve is that the barrel can't be too large, otherwise it would collide with the pressure chamber. The 1.5" barrel is probably the largest diameter that would work alright with this valve.

[lew0004]

what size wood a tennisball need.

[matthewbeckler]

Spudtech sells 2.5" Schedule 40 PVC that fits tennis balls. I have never purchased any pipe this size, but I've heard of people getting good results.

http://www.spudtech.com/detail.asp?id=38

[stuffman366]

try thiswww.spudgun.com/product.htm

[mettaurlover]

i'd use shooter marbles as ammo. lots of them. you ever seen what happens when a marble hits a wall at 300 FPS? it explodes. loudly.

[The 4th Doctor]

You should use some disposable cameras for your firing circuit i bet you could get a pretty good power increase if you try it tell me how it goes

[covey12]

why do you even use nine volts? it has so much less power than operating the valves when pneumatically modded. you should look up on spudfiles.com how to mod a sprinkler valve, it uses a blow gun as a filot so you have an actual trigger on the gun

[matthewbeckler]

4th Doctor, Thanks for the comment. I don't think that the current firing circuit of 3 - 9v batteries and a switch impacts the power of the cannon. I could certainly get a more powerful cannon by modifying the sprinkler valve, but I haven't done that yet.

[The 4th Doctor]

the 330volt pulse capacitor in disposable cameras should open the valve faster which should increase the power of the cannon, maybe a small pointless increase maybe a pretty decent increase or maybe something entirely unexpected too

[matthewbeckler]

Certainly, a quicker-opening valve would increase the amount and rate of airflow through the barrel, but I don't think the limitation is from the electronics or the solenoid, but rather the diaphram action of the sprinkler valve. In addition, the huge voltage spike would probably damage the solenoid coil, as they are really only designed for up to 30v operation. A quick google search can help you find videos and instructions about moding a sprinkler valve:

http://www.google.com/search?q=mod+a+sprinkler+valve

[The 4th Doctor]

ive used solenoids alike to the solenoids in sprinkeler valves the capaciters give a pulse that they put up with fine and give a quick strong pull which should open the valve faster it could be a pretty pitful or a pretty impressive increase it should help itleast somewhat and its simpler then modifying valve all you need is a disposable camera if anyone trys this post results

[qballcat]

urs looks cool :D check out mine plz

[diablo735]

Out of curiosity (this lack of curiosity may kill the cat. :P), anyways, I am not sure whether you should or must drill the hole for the tire valve stem where the pipe and end cap meet or it does not matter? Thanks for the reply(-ies) in advance.

[matthewbeckler]

I've never had a problem with putting the tire value stem in the middle of the the end cap, but some people suggest drilling the hole where the end cap overlaps with the pipe.

[clemsonguy1125]

I would not use it in snow cold weather weakens pipe

[Dr. Explosion]

The valve you used makes the coolest noise! You should try modding it to be manual for more power, if you don't know what i'm talking about, search "mod a sprinkler valve" on youtube. I don't know if it would work on your type of valve though.

[DYLEGO]

actually, with 27volts it has more power than manually, also you press a button and it fires!

[Dr. Explosion]

oops, UberNoober already told you to do that but oh well

[UberNoober]

Wow, amazing. This is easily one of my favorite instructables ever. You really go in depth with the instructions, and even focused some on that *safety thing*... I am currently making a similar air cannon/spud gun/Pneumatic Thingy Of Doom, mine having a few minor differnces from yours. I'm using a Rain Bird 1" straight valve, and used two 90 degree elbows. I also modified said sprinkler valve with a blow gun valve to increase the speed and efficiency of the air cannon. YouTube "How to Mod a Sprinkler Valve For Pnuematic Cannons" (or something like that) to get what I mean.

[UberNoober]

Here is a diagram of what my cannon *should* come out like when complete, note the green square is the modded sprinkler valve.

[DYLEGO]

if you havent made it yet, a better and cheaper idea would be to put the sprinkler valve on the bottom layer and use smaller corner turns, like 1 or 3/4 inches, whatever sprinkler valve takes.

[cowscankill]

Can you help me? I bought a valve and modded it, but it had a hole in the center of the diaphram. When I pumped the gun, the air pressurized, but when I pressed the trigger, the air came out the blowgun trigger instead of the barrel. So I plugged the diaphram, and now the air comes out the barrel, but the trigger doesn't stop the air from coming out. Does your diaphram have a hole in it? Does it need to be there? I would like and answer ASAP. Thanks.

[blugyblug]

OMFG its the DWV POLICE. The elbows on your picture are DWV lol... just in case you were actually going to use DWV for the real gun.

[Mr.Bean]

about how much did this whole project cost?

[matthewbeckler]

I'd say less than $50 total. The fittings are about a dollar each, the pipes are a couple dollars each for 5ft sections. The big expense is the valve, which was $15-$20 I guess.