Pneumatic Snowball Cannon




New England just got it's first snow, now to make use of it. I know a lot of people make Potato guns, which are pretty much the same, but I find shooting food pretty pointless. Snowballs are funner, and less destructive. Your total cost for this will be about $45, if you already have an air compressor. If you don't, you'll have to buy one, which can be costly. I had a compressor, but I just wanted to get a new one.
All the parts used in this instructable came from Lowes, except the compressor. The photos are tagged with the part number and price from lowes.

Gun in action:

Second version gun in action:

IMPORTANT: Skip to last step for a slightly more expensive, but better version.

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Step 1: Get the Parts

Most of the parts are made by Kobalt, which is the Lowes version of Craftsman from Sears. They're pretty good quality by my standards.
The air compressor was from Sears, it's the Craftsman 1hp 3 gal. Air Compressor.
You can choose to build a 2 inch pipe model, or a larger one, either 3 or 4 inches. You'll only have to get a different size cap and pipe size.

Here's the list from Lowes:
- (Two of these) 1/4 to 1/4 Male coupler - $2.19 - #2270 (Their image is incorrect)
- 1/4 to 1/4 Female coupler - (Not sure of the price or where go get one, it came with my compressor)
- 2" PVC cap - $0.52 - #23406 (Not available online, easy to find elsewhere)
- 1/4 mini ball valve - $7.96 - #221029
- Pressure Gauge - $7.94 - #221022
- 7/16th drill bit - $7.58 - #219842 (Not available online, and you can find them anywhere, probably cheaper too)
- 1/4 NPT Tap - $9.97 - #232530
- 2"x5' PVC Pipe - $3.97 - #23833 (Not online, but easy to find)
- Compressor air adapter - Depends on what kind of compressor you have. (It'll most likely be a 1/4th NPT thread)
You'll also need an old, empty propane tank. If you don't have one, you can get an oxygen tank from Lowes for about $5. Thats the cheapest kind of tank you'll find.

For tools, you'll need a grinder (Or a hack saw), some vice grips (Or a tap wrench), a cordless drill with a clutch, a 5/16th ratchet socket thing, and some misc Allen wrenches.

Step 2: Burn Off the Propane

You will need a 100% empty propane tank to do this, otherwise, you'll have some interesting results when you start drilling.
I just lit my torch, and left it underneath my porch, where we store fire wood. It's the only place that's outside, not covered in a foot of snow. Thank god nothing caught fire.
Do NOT do it inside, burning Propane lets off Carbon Monoxide, and burning out an entire tank, or even half a tank, could let off enough to kill.

If you use oxygen, I guess you can just let it out.

Step 3: Drill Your Hole

This first hole is going to be for the pressure gauge. I didn't have a center punch, so I used a Phillips screwdriver and a ratchet. You want to make 2 holes, one for the gauge and one for the air inlet. I put them opposite of each other on the bottom of the tank.

When you drill, I suggest first making a smaller hole, followed by the big 7/16th one.

Step 4: Tap Those Holes!

Time to tap the holes. I like to fasten my taps in a vice grip as illustrated in the second picture. It holds it way tighter than the other way, surprisingly. And a side note, do NOT loose your tap inside the cylinder. It is no fun at all to fish it out. I accidentally lost mine, and I had to fish it out with a magnet and some needle nose pliers.

Step 5: Put in the Gauge and Inlet

First wrap the threads in Teflon tape, just for good measure. Don't use too much tape, just wrap it around the threads twice. Too much will rip off when you screw it in. And also beware, if you over tighten it, it will mess up your threads, because the metal isn't that thick.

Step 6: Modify the Ball Valve

The ball valve is designed to stop after turning 180 degrees, which isn't what we want. This, like a normal ball valve, is open with a quarter of a turn. 180 degrees is 2 quarter turns, so it starts on off, and stops on off. You need to take out the hack saw or grinder for this step. First, you have to take off the bolt that holds on the lever. Then chop off the section shown in the first picture.

Step 7: Create the Automatic Firing Mechanism

You obviously can't open the valve fast enough, being a human and all, but don't worry, I have a solution for that. First, you will need a 5/16th socket, from a ratchet. This should fit perfectly over the bolt for the lever on the ball valve. If you're using another ball valve, just find one that fits.
Now, check if that socket fits in your drill. If it does, you're all good. If not, you'll have to do what I did. Find an Allen wrench that fits into the opposite side of the socket, and make sure it doesn't spin when you put pressure on it. Do not try to over turn it, you'll strip the threads. I stripped mine, but all I had to do is take off the washer and use the threads there. Anyways, once you make sure it fits, you'll have to cut off the shorter half of the Allen wrench, so that it spins right. The first picture is the valve with the socket and wrench all set up. You can use a hack saw or a grinder, I choose grinder for this one, because it's less delicate. The long side of the allen wrench will go into your cordless drill, to fire. This is why you need a clutch drill, you have to put it all the way on 1, so it'll open the valve and start slipping when it hits the stop.

Step 8: Drill and Tap the Valve's Hole

I decided to drill a hole in the top of the propane tank, so the entire thing looks streamlined. It took a while to drill through the top, and its harder to tap, but it's worth the better look. For this one, I just went straight in with the big drill.
When you're done, this hole will be hard as hell to tap. You'll need LOTS of wd40, i used half a can, and you'll need to do a reverse turn every 3 turns. I even managed to dull my tap on it. Oh well, gives me a good reason to return it, I guess.

Anyways, once you're done tapping, you should put some Teflon tape on, and screw in the valve. I had to grind the handle down a little, so it doesn't hit the tank on the way down.

Step 9: Pressure Test

Just to make sure it can hold pressure, I'm trying it on 40 PSI. Check out the video.

Step 10: Modify the PVC Cap

Drill a hole in the cap with the 7/16th drill bit, make sure its in the center, otherwise your snow ball will spin. After that, tap it, and thread your second 1/4 to 1/4 male coupler through it, making sure that you're threading from the side that will end up on the inside. Once all the way through, attach the female to female connector to the male to male one. This will connect the PVC pipe to the air tank. The picture is of the finished connector, I forgot to take pictures of the process.

Step 11: Glue the Cap Onto the Pipe

Clean the pipe with the pipe cleaner, then clean the cap. Then apply glue to the cap, and put it in. Don't get glue on your fingers. It sucks to get off.

Step 12: Assemble Parts

Screw the cylinder into the PVC pipe. You should be done.
I choose to duct tape a piece of wood to both the tank and the PVC for support, since that cap can't hold a lot.
I later found out that that cap, was a piece of crap. It broke on me.

This is what version 1.0 looked like, 2.0 is on the way.... with improved PVC pipe, and using only one drilled hole at the top of the cylinder.

Step 13: Version 2.0

I didn't want to write a whole new instructable, but with some extra hardware, you can make a much better version.
One of my friends leaned against the air inlet, and caused it to break out of the threads. So that inspired me. This only has one hole drilled, in the top. It's way more reliable. There's about an inch of metal to tap, compared to a millimeter. The improved version is also portable too.

You'll need these additional parts:
- 1/4 npt female to female coupler
- 1/4 npt 3 way adapter (2 of them)
- Second ball valve
- And possibly a new tank.



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    113 Discussions


    4 years ago on Introduction

    Use a real tank with NPT thread. You are so dumb. If you do this, use a fire extinguisher and hydro test adapter or steel/copper pipe for the chamber. When drilling, you may ignite remaining propane fumes. The fittings can also blow off. The quality is like a kindergardner poked holes in the tank and then used a glue stick to glue fittings on top of the holes.


    11 years ago on Step 13

    Your techniques and use of tools is laughable and DANGEROUS. Messing with cylinders is ill-advised. Find a drill press next time. Next version how about a stock, sights and forestock? Its a decent try (for an 8th grader...)

    8 replies

    Actually using a propane/oxygen or any metal tank that actually handle pressures much higher than 150 PSI are a hell of alot safer than PVC! PVC if over pressured shatters into billions of pieces and can embed itself into your body. A metal container would most likely rip at the weld seams before it would explode. ABS is bar far the best to use because it rips instead of blowing into millions of shreds. the only downside is its pressure rating is much lower than PVC. BTW SCH20 PVC is rated at 300psi and typical oxygen tanks are rated 500-1000 psi. My paint ball CO2 tank is constantly pressurized and unpressurized at 3000 psi! Oh yea and CO2 tanks get cold when they depressurize, WELL below freezing!!!! they can handle it well.(that being the pressurized tank side). Moving on to the barrel... the idea of the PVC pressure test cap you used was a bad idea... but the barrel is never pressurized enough to do harm... that said, if you can shove something down the barrel, the air that is about to escape will shove back out of the barrel with very little PSI, nothing to fret about. Ive got a Bachelor's of Science in Aerospace Engineering at Auburn University in Alabama and live in the Engineering Rocket City a.k.a Huntsville AL, don't EVEN Question me!

    p.s. lay off on cvxdes, he's just making an instructable that for the most part is safe. although drilling into a propane tank is a bad idea because one spark = boom, follow watterppk's advice and drill underwater or use an air compressor and blow it out for a long time.


    propane tanks are 100% fuel environments unless theres something wrong with the valve. propane + No oxygen = NO explosion. if anything adding compressed air would be a very bad idea


    I agree partially, but to create an explosion you need heat or a spark. decompressing air actually takes away heat. Besides i meant like using a blower nosle to blow out the propane tank after all the propane has been released and the propane tank valve has been removed, no compression at all.

    mainahThe Expert Noob

    Reply 6 years ago on Introduction

    Bachelors in Aerospace Engineering- OK Jr. High spelling- not so good Ex. Nozzel instead of Nosel. Don't they have Nozzels on Rockets? ;-0

    kibblerThe Expert Noob

    Reply 10 years ago on Introduction

    Not for all explosions, if that's what you were saying. I have overpressured a piece of PVC and it blew up, with no spark. But you are right about the latter.


    Reply 10 years ago on Introduction

    Technically, it didn't blow up. It shattered prom overpressurivation, and if there was a boom sound, it was escaping air.


    11 years ago on Introduction

    I'll pass on the being specific and the elaboration. Clearly from your tone there is no benefit you'd be willing to recieve from a 30+ naval avation machinists mate, but... One nice thing though I feel compelled to put out there is your idea is good one.

    1 reply

    Reply 8 years ago on Introduction

    I think this is a good build. The fact that he used a propance cylinder is a bit questionable, but i find it to be safer than PVC, especially in a colder environment (remember, this is a SNOWBALL cannon.) Aslo, it doesent have to look amazing, it just has to work.


    9 years ago on Step 4

    where would you get a tv that big?

    rock climber

    10 years ago on Introduction

    I have found that propane and oxygen tanks are 3/4 in threads. I use this instead of the 1/4in thing. By the way this cannon is great especially version 2.0 but i would recommend an oxygen tank.

    2 replies

    ooooppps I was wrong, propane tanks do not have 3/4 threads. And no, instead of using the oxygen tank that I recomended use a footlong peice of 2 in galvanized steel with a cap on the end. I would also recomend using an "over under" design that includes a quick exhaust valve. This is how my newest cannon is designed and it shoots potatoes and tennisballs over 160 meters.


    9 years ago on Introduction

    That's not looking to be safe. Propane tanks are dangerous, much MUCH safer to just make a container from some 3 inch pipe. And it is probably hard to open the valve, so you will jerk the gun and then your aim will be off.,


    10 years ago on Introduction

    This is just a thing i heard but appareantly when your tapping you cant use oil or lubricants as it puts pressure on both side of the threads top and bottom making it harder this also works with bolts


    11 years ago on Introduction

    although i agree with that your fairly lucky not be injured while doing your project.... dirjushunting you should not be picking fights. cvxdes you should not be encouraging. and why cant we all just be friends? cvxdes good work.