Material for snowball cannon?

[JEK3]

I am looking to make a snowball cannon (just got 15-18" over the weekend). I would prefer to work in PVC, but that would be kind of dangerous in the cold weather. It would have to withstand up to 100psi at about 30 degrees F., and I would like the barrel to be on the order of 1.5" to 2" in diameter. I have access to the normal hardware-store variety of materials. What do you recommend I use as a material?

[kjjohn]

Copper, steel, or aluminum. Black or galv steel pipe and fittings can be bought at most hardware stores, as well as copper.

[Lockednloaded]

definitely go with metal, PVC is VERY dangerous with cold. I think one of BTBs cannons blew up just by using ice ammo. If you can't work with metal i would probably go with sch 80, I'm not totally sure, but it seems less prone to exploding in the cold, but I have never worked with sch 80 so I may not be right
@kkjohn- copper fittings in the 1 inch and up range tend to be very very pricy, wouldn't recommend it

[SpudBlaster15]

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[JEK3]

Thanks for the input so far. I kind of knew the answer already before I posted my question, but I still wanted to get some input.

I would prefer to use a barrel- or chamber-sealing design, rather than a ball valve. I was planning to slow down the shot by reducing the pressure, although I could also shorten the piston travel to throttle the flow.

How about a copper valve body, with an ABS barrel?

[SpudBlaster15]

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[Biopyro]

The pressure rating of PVC actually increases when it's cold, but it's shock resistance decreases as it becomes more brittle. Something like a piston slamming into it, a lot of recoil force focused on one joint or dropping it might be enough to crack it and the pressure would do the rest. Best to steer clear for something like this, but it doesn't mean PVC is unusable in cold weather.

High acceleration will give you a useless mist of snow, so you'll be best off with a slow valve at low pressure, not more than 50psi. I think the safest route would be to have a foam sabot behind the projectile to stop air rushing through the air gaps in the snow and tearing it apart.

[bradisfun]

i think that u dont want to be carrying around a heavy canon
so....................
i think that u sould make it out of PVC but then get some 4-5" PVC and sleving in that and then inbetween the 2 u can fill it with expandable foam

[psycix]

I'd go with metal construction, because I do not like surprises when pulling a trigger.
Stuffing the whole barrel full of densely packed snow (because you can't resist) might blow a PVC gun that survived hundreds of normal snowball shots.
You will never be safe with a subzero PVC cannon.


Large diameter thin wall metal pipe, ball valve (or just slap on a QEV), start at a low pressure, slowly work your way up.
Small chamber, onboard pump.

[SpudBlaster15]

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[psycix]

Which is one of the reasons I switched over to metal cannons.