Introduction: Air Cannon V3

Picture of Air Cannon V3

A pneumatic cannon for launching plastic soda bottles.... or ketchup packets. Almost all parts can be obtained from home depot and probably any local hardware store with a plumbing section.

Bigger is cool looking... But not always better. I have found smaller more robust designs to be far more fun that the gigantic heavy cannons. I can recharge (with a foot pump) and reload in less than 30 seconds and hold this thing much easier than its heavy breathing counterparts. Other than this design, I no longer build using PVC as it does fail catastrophically.

I made this particular cannon to be used for physic's demos for middle and high school physics students. 2l bottle fail at surprisingly high pressures (relatively) and have served as a reservoir very well.

Step 1: Parts List

Picture of Parts List

All parts are 0.5" unless specified

1 2l bottle of soda - minus the soda and washed out
1 .75" sprinkler valve with manual switch
1 45 elbow
2 female/male 90 elbow
1 female/threaded adapter
1 end cap
1 .5" thread-> .25" threaded bushing (mine is galvanized)
3 1.5" long pieces of pipe
2 2-2.5" long pieces of pipe
2 .5" female - .75" threaded adapter
1 4 wayfitting
1 Tire Stem with schrader valve (walmart or autoparts store) - home depot did not have this item
PVC cement
Teflon Tape
1 male threaded cap OR 1 gauge (might be listed as manometer)

Optional Add on (for bypass and a later project)
3 more 1.5" tubes
1 ball valve
1 45 elbow
1 3 way Tee

Step 2: Prepping Components

Picture of Prepping Components

Disassemble your valve. I am not going to be modding it as it is really unnecessary for this project. Taking it apart simply makes it easier to paint.

While the paint is drying (if you choose to paint), now is a good time to cut your tubes if you have not done so already. PVC saws (looks like a metal string) are cheap and effective. I personally use a band saw to zip though everything. Guitar strings also work, just be very careful - it will eventually snap and the filament will be extremely hot (I've had burns from this). Guitar strings also have a tendancy to wrap themselves around when they snap.

Now is also a good time to sand off any burrs and lightly sand the mating edges of the fittings and tubes.

Step 3: Make a Filler Valve Fitting

Picture of Make a Filler Valve Fitting

Using a dremel (or even a regular drill) -- cut a hole in the center of your cap. Chamfering the inner edge will help greatly in getting the stem on.

Tire stems are a press (or pull :P) fit. So make the hole as small as you possibly can. .5" caps are a tight fit, but it fits nontheless.

When you think you're ready -- push the stem through the back of the cap. Then pull it through as hard as you can. Pull one way and then another direction until you notice an edge pop out and set itself on the outside of the cap.

Step 4: Fitting It All Together

Picture of Fitting It All Together

Hopefully you get the general idea from the picture of the end goal.

The longer lengths of tube are for the reservoir (2l bottle) and for the filler stem post. Ideally, everything should be in the same plane except for the gauge post. Therefore, I recommend you make attaching the reservoir the last thing you cement together. I find an angle of about 45 degrees is ideal for the gauge post - this allows your hand to naturally hold it and allows easy viewing of the gauge while refilling.

If a part has threads, do not cement. Instead - wait until after you paint (if you choose to do so) and use the Teflon tape to seal everything.

The last picture is with the optional add on. Everything AFTER the ball valve was not cemented in place. It will not be holding pressure and allows me to change my mind on what should go there (ie another 2l bottle). If anyone needs a better description, let me know and I'll take the time to go more in detail.

Step 5: Final Assembly, Safety and Firing

Picture of Final Assembly, Safety and Firing

When the cement has cured for a few hour you can not attach the sprinkler valve. Be sure to use teflon on the pressurized side.

Keep tightening and make sure you stop when the solenoid is facing downward. This makes a nice little point to grab on and puts the manual bypass switch at your fingertip.

I currently use a 3' barrel. Honestly, this is too short for loaded projectiles, but it is almost too big for water bottle rockets.

SAFETY
I always pressure test my guns above what their normal operating pressure is. I tend to stay around 60psi and I tested at 90psi. I attach my air line to the filler valve and place the whole thing in a wooden box. I then slowly bring the pressure up to 90psi and I stay here for about an hour.

FIRING
I purposely leave the teflon tape off of adapter on the barrel side. This allows me to unscrew and make the whole thing easier to transport and load projectiles. I find that ketchup packets will fit if coaxed in there slowly while twisting. But, don't fire at higher pressures - otherwise the packet rips open inside the barrel and a rectangular foil wrapper shoots falls about 3 feet away.

Firing water bottle rockets: Fill a 2L (or even a smaller 20oz bottle) a third to halfway full and set it on the ground. Charge the reservoir to your firing pressure. When you are ready to fire, make sure your firing range is clear and push the barrel into the full length of the bottle.. Pick up the whole cannon/rocket and point upwards. Let everyone know you are about to fire and pull the trigger.

You will get wet -- I tend to hold it out the side a little bit.

Comments

DanTDM (author)2014-01-31

Only use galvanized, black iron or copper pipe for air cannons. Also, only use air tank valves, not homemade systems. NEVER use drink bottles for storing compressed air, they will rupture very easily.

bruster999 (author)DanTDM2017-09-19

I would caution against using very high pressures as well. You really don't need high pressure as much as air volume. My project (above) uses only 30 lbs of pressure and sends a 3" rubber ball at least 50'. I built mine for my dog though and he just loves to chase that ball! LOL

DanTDM (author)DanTDM2014-02-08

Oh, and by the way, use a used fire extinguisher, small air tank or other strong metal tank designed for high pressure gasses.

crashbash (author)2011-07-08

Is there an adapter from the PVC screw to the 2L bottle screw? Also if you wanted to make this a paintball gun, put a 3 way connector on the part right after the sprinkler valve, the extra connection facing up, fill a 2L bottle with paintballs and screw in! the paintballs will fall into the chamber to be shot out like a real paintball gun!

bruster999 (author)crashbash2017-09-19

I struggled with that as well. I tried 3D printing an adapter but it didn't hold air very well and I didn't know a garden hose adapter would work so I substituted the 2l bottle with a length of PVC pipe instead. That way you can use PVC for the entire project. See my pics above.

DanTDM (author)crashbash2014-02-08

2-liter bottles use garden hose threads. Just buy a female garden hose to pipe adapter.

bruster999 made it! (author)2017-09-19

Thanks for the inspiration! I used your basic premis and built my own on a slightly larger scale. This version uses a standard air compressor and a 12v motorcycle battery to create the pressure. Air is stored in two 3" PVC storage pipes on the sides released into the main cannon using the same irrigation valve you used. I know the valve actually needs 24vAC to work properly but 12v DC works great for just a quick open/close. I couldn't find a ball to fit the 3" cannon tube so I made a carrier/piston on my 3D printer so that any ball less than 3" can be used. A stop inside the cannon tube prevents the carrier from flying out each time and an elastic band will retract it back to home. Eventually I plan to house this in a wooden enclosure and automate it with a microswitch to trigger the air compressor. Most likely I will add an Arduino and a pressure sensor so I can fine tune the pressure (30 lbs sends the ball right across my 70' yard).

The creator2 (author)2015-10-11

Cool

KJ4ZVQ (author)2011-07-27

mod an EMPTY coleman campstove propane bottle, and i bet you could run 200-300 psi easy :-)

DanTDM (author)KJ4ZVQ2014-02-01

Yeah, EMPTY. Full ones will go BOOM

that's right buddy.

ElectroFrank (author)2011-09-10

I would like to suggest that all high pressure air cannon instructables should include a warning such as:

"These high pressure air weapons can shoot things fast enough to cause severe injuries or death. Never use them to shoot things at people."

think3000 (author)2011-07-23

I built a cannon sort of like this one for launching tennis balls and t-shirts i used an inner tube bike pump adapter attached to my air compressor and i can shoot them well over 150 yards i wonder if you hooked yours up to an air compressor it might go farther.

crashbash (author)2011-07-08

The model I bought looks EXACTLY like this exept for the flush trigger, it doesnt have one, its made by the same manufacturer and its the same model, did they remove it from the design?

AdmiralNiik (author)2010-05-16

 You say you no longer use PVC for safety. What do use now?

pfdanielson (author)2008-12-01

do you have to use an orbit valve? I have a rainbird that isn't in a cannon yet. will that work too?

toogers (author)pfdanielson2010-05-15

if you are still wondering, yes, it will work.

knex luver123 (author)2010-02-20

i luve the hair harry potter

The Lightning Stalker (author)2007-09-13

There's this "plastic fusion" paint that might stick really well depending on what kind of plastic the valve is made of. There's something that works even better than a band saw or friction saw/guitar strings. They make special PVC "scissors" that have extra leverage and a ratcheting mechanism. They're the best thing to use on smaller diameter pipe. They cut clean and leave no shavings.

     I've seen those "PVC scissors" before, maybe on TV. They're incredibly, but not as much, huge. Should be easy to spot when you need it. Unless you were in a warehouse it would be lost for sure.

I've never seen one that big.  They're usually about the size of tin snips and can cut pipe up to like 1.25".

nutsandbolts_64 (author)2009-12-03

How much does this cost? I would like to see something below Php 300.00=6 dollars, because I'm in a tight budget here. Not much spare money for me to go on.

raziel47201 (author)2009-11-21

I have to ask just for curiosity sake if i decided to use copper pipe for this air cannon and a empty fire extenguisher bottle for the reservoir how many psi would it approximatly hold and would it be safer? because ive known the integrity of pvc and any other kind of plastic to be compremised in colder temperatures around like 30 degrees farenheit or so.

pirate of doom (author)2009-03-25

if the bottle gets scratched...... Hopefully your face wont be ripped up.

PET tears, it doesn't make shard fragments ;)

Thundertydus (author)trebuchet032009-05-26

I have a challenge for you! can you make this so that it has a 1 shot capacity, and shoots a huge cloud of flour? Plz ibby it

Charles IV (author)Thundertydus2009-07-24

All you have to do is stick some flour down the barrel. That's the beauty of pneumatic air cannons you can shoot anything at the neighbors as long as it fits in the barrel... and if it doesn't make it bigger ; )

Thundertydus (author)Charles IV2009-07-25

Well, i know that, but i mean, add like a clip or something, that has ejecting shells with compact flour in them or something like that

Charles IV (author)Thundertydus2009-07-31

You could try wrapping a piece of paper around an item the same diameter as your barrel then fold over one end, put the flour in, then fold the other end over. So when you fire it it blows out the paper on each end and shoots the flour.

Thundertydus (author)Charles IV2009-08-02

Didnt think of that, great idea!

foxtrotfire (author)trebuchet032009-05-05

it will hurt your ears tough (and trying to put about 10 bars on a PET bottle is a BAD idea, trust me>_<)

ilpug (author)2009-06-18

oh ye of little intelligecne... thiz is a great design with lots of potential, just why do you insist on using such a wimpy air resevoir??? soda bottles are really dangerous when they explode, and damage your hearing alot. overpressurize this and you will get holes in u. use five bucks and make a one foot long, 2 inch diameter pvc chamber that you can get up to 120 psi insted of the little 20 psi you have in that bottle. also, why dont u make a differnet desighn to make it easier to hold? just idle critiszizm...

trebuchet03 (author)ilpug2009-06-18

just why do you insist on using such a wimpy air resevoir???

Because the math states the reservoir is too big for a reasonable length barrel.

soda bottles are really dangerous when they explode, and damage your hearing alot. overpressurize this and you will get holes in u.

Damage hearing, sure - if it ruptures... "Holes?" Not likely - this is why I pressure any pressurized device I make while filled with water. Luckily, overpresure for a PET bottle is in excess of 120psi.

use five bucks and make a one foot long, 2 inch diameter pvc chamber that you can get up to 120 psi insted of the little 20 psi you have in that bottle.
That would be about 1/5 the volume and about a quarter of the energy at the pressure's I run... I run at 90 psi max - various resources claim soda bottle failures ranging from 120-180 psi - and I'm okay with running a 1.33 safety factor with this sort device.

Really, I find 40-60psi the optimal zone for water bottle rockets. More than ~40psi tears ketchup packets before they get out the barrel.

also, why dont u make a differnet desighn to make it easier to hold?
Hey now, don't knock it until you've tried it. It's not only easy to hold, it's intuitive to new people. One hand on the valve solenoid (easy access to the trigger) and the other on one of the back.




All that said... I published this in mid 2006 - I build the first one in early 2006 and the second one shortly before publishing. Since then, both have fired literally hundreds of water bottle rockets (and the occasional ketchup packet). It's been highly successful, reliable and aesthetically pleasing. And since it's got more than just PVC pipe, police officers have either liked it or taken no interest (both good for questionably legal devices).

smithn (author)2008-01-08

How exactly did you attach the bottle? just glue or some threaded piece? and how exactly does a pvc one fail, is it for safety or it just holds poorly?

milo0is0hot0 (author)smithn2009-03-21

yeah it is not funny!!! I was trying to be careful when I pumped up the pressure in a bigger pvc cannon but the gauge I used was broken (I found this out afterwards) when it blew it does not 'split' or blows it to hundreds of sharp fragments!!! I had several pieces of pvc embedded in my arm and my leg!!!! not nice!!! I now use steel...because if it blows it will usually split...and the pressure required to break steel is far more than I can easily create!!!

starwing123 (author)smithn2008-10-15

It fails by exploding and sending PVC all over the place at very high speeds

Shagglepuff (author)starwing1232009-02-21

Then screw this thing, lets make a PIPE BOMB! : :-) :D :> ☺

frankinator (author)smithn2008-01-20

how i attched mine was i heated it up and screwed it in and repeated the cycle till it fit a 3/4 inch female fitting

starwing123 (author)frankinator2008-10-15

Just use an 1 inch female threaded addapter

trebuchet03 (author)smithn2008-01-08

A lot a lot of glue ;) PET (soda bottle) and PVC are not compatible and won't solvent weld.... But lather on a lot of glue and it should be fine (just pressure test to ensure it's a good seal)... For failure.... It breaks into shards - due to it's brittle nature... Throw a bit of pvc under a towel - then smack it with a hammer until it breaks... That's what failure looks like... Virgin PVC really isn't an issue - it's just as it ages and as it gets dropped, scraped, dinged and hit that you start tempting failure :/ But if your weld joints are good - it will hold pressure.

Coffee bean (author)trebuchet032008-07-20

but if your using a Pet bottle that will fail first.

baheuwill (author)2009-03-18

We can get the ball valve to work with ours but not the sprinkler valve. Too much pressure going through even with 3 9V batteries. Do you have any advice?

trebuchet03 (author)baheuwill2009-03-18

Are those 9V batteries in series, or parallel? How much pressure are we talking about? In another canon of mine, a single 9V battery wouldn't open the valve when the pressure was above ~50psi - which is plenty enough to launch T-shirts and other such items we were loading. If the valve is oriented the wrong way - it won't work... Assuming it's a diaphragm type valve.

Deathcapt (author)2009-01-22

I was thinking the same thing, it's basically the muzzle loading, musket version of a paint ball gun. You should get one of those battery powered bicycle pumps and you'd have a much faster reload, maybe if you got a bunch of people with similar weapons, you could play some civil war style Paintball

volquete (author)2009-01-18

i am going to make a movie!!! do you think i could attach a rubber hose to the end,fill it with blood(fake blood) and it would shoot the blood out? what kind of hose? how to attach it?

turkeypig144 (author)2008-11-21

I used baking soda and vinegar and its perfect you should try to put a third of a 550 ml bottle of vinegar then put half a cup of baking soda in a towel wrap it the put it in the bottle then put cap quickly shake and the bottle explodes in like 10 secondes its pretty cool i got vinegar in my eyes it burns .

the mysterious unknow (author)2008-11-10

What do you shot out of that?????????????????

bruno13069 (author)2008-11-06

Something to keep in mind. Garden hoses and 2-liter bottle have the same threading. A number of times at work I've needed a pressure cap for the hose to power flush the gap between the curb and the pad under the drive-thru window. Use a hot nail or a leather punch to make a small round hole in the center of the cap. The smaller the hole, the better the jet pressure. Screw the cap onto the garden hose. You can use the tape to get a better seal, but I've never needed it.

starwing123 (author)2008-10-15

Where did you get the sprinkler valve?

trebuchet03 (author)starwing1232008-10-15

Hardware store ;)

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