Pneumatic Snowball Cannon

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.

Comments

[dirjushunting]

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...)

[The Expert Noob]

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!

[mrtoast9000]

could you maybe use a fire extinguisher (cylinder) instead of a propane tank?

[The Expert Noob]

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.

[irwinner]

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

[The Expert Noob]

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.

[kibbler]

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.

[RMConstruction]

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

[cvxdes]

(removed by author or community request)

[Brandon121233]

I would have to agree with dirjushunting on this, the build quality looks like something out of middle school. First of all modifying a propane tank to fill it with pressures it was never intended for is a very bad idea, I would pick a PVC tank for safety over that shoty tank any day of the week. Secondly that PVC end cap looks like an accident waiting to happen. Thirdly I feel really bad for what ever company your working for if your a machinist. Any person with half a mechanical brain knows that tapping a curved piece of 3/16th inch steel for a pressure fitting (and no Teflon tape on the list) is poor construction quality. No machinist would ever let a piece of crap like that ever been seen by any one. I personally would pick steel mesh reinforced PVC to any other kind of cannon material. My latest cannon has a 4inch by 3 foot tank with a 3inch 10 foot long barrel. I made it for under $40, which is cheaper than your and probably has triple the range and wont kill me one day.

[James (pseudo-geek)]

those things hold up to 150 psi normally, and are rated much higher. a disposable fire extinguisher is rated at 300 psi max. yes, I did see for myself, I checked the label. and a propane torch will hold far more pressure than a disposable fire extinguisher.

[Brandon121233]

yes but the keyword is "normally" as soon as one starts to tamper (IE drill holes, tap with hammers, and TAP) with that vessel, that rating no longer applies. I would not be too concerned with the tank bursting as much as I would be concerned about the pressure gauge or fill nozzle bursting out of the threads and seriously injuring someone.

[James (pseudo-geek)]

ah true. I didnt think about that.

[The Expert Noob]

when I built mine using a co2 tank i used the existing fill/release port, pulled that out and replaced it, all the fill and pressure gauges were on T fittings. No modifying to the tank structure at all.

[your_shadow92]

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.

[James (pseudo-geek)]

/agree.

[dirjushunting]

I do not make anything that is plastic. All of my work, paid and for recreational use is stainless steel or alminum.

[iBurn]

...then...why are you on this instructable...?

[dirjushunting]

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.

[ilpug]

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.