do you think my gun will explode?

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Mr. Gopher Killer
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Sat Mar 24, 2007 11:31 pm

I found some 6 inch abs sch40 cellular core pipe at work the other day and decided to use it to make a huge potato gun. the chamber i built with it is propane injected and is 32 inches long. I double layered it buy cutting a seam down the side of another pice of the 6 inch pipe and glued it over the chamber but there is still a 2 inch gap on the side from the seam i cut to let it fit over the chamber. This thing is huge it makes the gun i made out of 4 inch pipe look like a pea shooter. The only thing that bothers me is that the chamber is so massive I am having second thoughts about safety. Do you think this cannon will be safe to fire?
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Flying_Salt
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Sat Mar 24, 2007 11:34 pm

I strongly advise asking someone with more knowledge than me, because normally abs is fine for combustions, but this is cellcore, huge, and propane. I personally wouldn't use it, but you might be okay. Again, don't take my word for it, I think BLB knows this kind of stuff.
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hi
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Sat Mar 24, 2007 11:38 pm

It should be fine because combustions dont build up too much pressure. I have used abs on all of my combustions and they all work fine. Just make sure that the projectile is not to tight in the barrel. Maybe you should drill a small 1/32 inch hole in the chamber so that is if there is a mis fires the gas can escape. You should post you cannon, there are lots of people here that would love to see it. May be you should close the gap with duct tape (just a thought)
Flying salt beat me to the post, i have used both propane and mapp gas in ABS and it is perfectly safe, in my cannons. The cannon i used mapp gas and propane in has a 4'' chamber that is abpt 20 inches long, i havent had andthing go wrong with it and i shoot it every weekend. I have never used 6'' abs, so i dont know
fom
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Sun Mar 25, 2007 12:18 am

Pete Zaria has pressure tested cellular core ABS to 100PSI, correct me if im wrong on that.
You should be fine, even if it does explode (which it wont) it would tear along its lengths (which is only 2" of exposed pipe) it wont shrapnel.
I think your fine.
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WOW!!
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Sun Mar 25, 2007 12:57 am

I wouldn't. But thats me. to make it more safe you can use some pipe clamps on the chamber. And you can also wrap the whole thing is some super high strength HDPE tape.
sandman
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Sun Mar 25, 2007 6:53 am

it is why im getting pressure rated ABS, and if i were you id try it out with remote, and stand faw away
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jjjd
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Sun Mar 25, 2007 8:46 am

Yeah, i would do it... even if it does crack it will just split all the way down the side, but i would do a remote igntition fro the first few tries. just until your comfortable with it
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Fnord
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Sun Mar 25, 2007 9:23 am

yeah just remote fire to test it, then when you start using it wear gloves+eyeprotection+heavy clothes.
youll look like a dork but I wouldnt make fun of you when youre holding a cannon like that;)
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A-98
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Wed Mar 28, 2007 11:01 pm

as for the pipe, i would not use it , personally. i trust normal ABS, but this is cell core and given the large surface area, it will have alot of force exerted uppon it.
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pyrogeek
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Wed Mar 28, 2007 11:46 pm

I don't want to start the whole PVC vs ABS debate, but how can cellular core PVC be a no-no, but ABS (which is cell core) is considered OK?

Anyway, go ahead and test it out. I would say remote fire it with heavier projectiles than you usually would, so that if it fails it will fail now, instead of on your shoulder blowing up right next to your ear.
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frankrede
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Thu Mar 29, 2007 12:07 am

PVC cell core is brittle and ABS cell core has a high tensile strength and impact strength.

Its like comparing braided rope too braided steel cable.
But not as extreme.

Btw. Your cannon should be fine.
Do about 10 remote fires and if it is all good you should be fine.
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Zorrowannabe9
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Thu Mar 29, 2007 1:14 am

ABS is fine to use as a chamber material. Use it, you'll live.
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Thu Mar 29, 2007 10:34 am

I would be afraid that you cutting it made it weaker than it was before anything was done to it.
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Mr. Gopher Killer
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Thu Mar 29, 2007 4:25 pm

i made the chamber by cutting a piece of pipe and glueing the couplings and reducers on the ends. the only piece that i cut down length wise was an extra piece of 6" pipe i had then i sliped it over the chamber for some added strength
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tater36
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Thu Mar 29, 2007 4:41 pm

is pvc a better choice than abs? cause i want to build my first combustion and i want to know
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