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how much pressure???

Posted: Mon Jan 23, 2006 2:27 pm
by AcDc83190
hey im a newbie to spudguns and i recently built a pneaumatic cannon with a 2" chamber,3/4 barrel, and a ball valve. I used ABS for my 2" chamber and i now know that its not pressure rated but what would be a safe PSI to put in it. Any help would be great. thanks

Posted: Mon Jan 23, 2006 3:55 pm
by beebs111
i know its not pressure rated, but did u say you only used abs for the chamber? if so i would not reccomend putting much pressure into it at all because i dont think the joints will hold

Posted: Mon Jan 23, 2006 5:08 pm
by darkpyro
hey if you are useing a ball valve then you should be able to unscrew the compression chamber (which is made of abs) and make a new one out of pvc to screw on dont use abs or you will damage yourself. :(

Posted: Mon Jan 23, 2006 5:13 pm
by jrrdw
rebuild your gun with the rite stuff, a belly full of plastic shards aint worth the chance 4 real

Posted: Mon Jan 23, 2006 5:16 pm
by darkpyro
to right but you only need to rebuild your compression chamber just unscrew the old one and screw the new one straight in. :D

Posted: Mon Jan 23, 2006 7:07 pm
by Atlantis
As a warning, PVC nor ABS show up on X-Rays.

Posted: Mon Jan 23, 2006 7:10 pm
by theregoesthewindow
in my first potato gun, built with a friend not to long ago, i used ABS. only pressurized it to 30 psi though, still PVC is time tested and much safer to use.

Posted: Mon Jan 23, 2006 9:19 pm
by darkpyro
use pvc you idiot havent we made it clear enough !!!!!!!!!!!!!!!!
if you do use abs you can only take it to about 40-50 and even then its not safe and you wont have enough pressure for a good shot dont be stupid rebuild the cannon or someone is going to get hurt :x

srry to be harsh but i dont want you filled with pipe shards

Posted: Tue Jan 24, 2006 11:56 pm
by swim_scrub
If you consider analyzing it using plane stress methods it is pretty simple. I would recommend picking up a Mechanics of Materials book and reading the chapter on "pressure vessels."

Im not going to give you an answer because i dont want to be responsible for someone hurting themself with a poorly designed gun. But, this is how you would find the "theoritical" limit of the gun.

Posted: Wed Jan 25, 2006 6:07 am
by Urban Ninja
Just replace the chamber, I would rather spending a few dollars on piping rather than it blowing up and having my ribs broken or dying. I built an ABS one years ago (I thought it was pressure rated picked up the wrong one at store, REtaRd) Pressurised it to 40 psi and boooom. The valve blew off like a missile. The whole barrel flew about 40-50 yards, no joke. Dont post Oh ninja ya moron, yeah I know I am but a few years ago I had no idea about spudding.

Posted: Wed Jan 25, 2006 8:23 am
by r0n
Im in ontario and i cant seem to find PVC ive looked in home depot and all i have found is the electrical PVC and ABS and PVC drain pipe which has holes in it. Could anyone point me in the right direction to where to find PVC?

Posted: Wed Jan 25, 2006 9:02 am
by Urban Ninja
Look in the yelllow pages for hardwre stores and plumbing supply shops. Or go to bunnings if you have one nearby.

Posted: Wed Jan 25, 2006 3:03 pm
by jrrdw
pvc + cold temp = disaster it's why it's hard to find in Canada, type plumbing supplies in googlee and you will find a order source