SpudFiles

i just finished my first pnumatic cannon...

i was lucky and found an old fire extinguisher that had a 1" fitting (not the slightly smaller thread they use now)..




yes its old (made in 1967) and has a little rust but its only on the base, and it will be cleaned up and repainted very soon...




it says it was tested to 450 psi and i tested it to 170 psi (as high as my compresser will go) and all seems well....

i only have a 1 mtr long barrel but at 80 psi i am able todo this through 12mm marine ply (the pipe is Al too so not much mass) :

Good stuff, one small point though - the chamber is terribly oversized in comparison to the barrel, you can afford to have one much, much longer and squeeze every ounce of power out of it

jackssmirkingrevenge wrote:Good stuff, one small point though - the chamber is terribly oversized in comparison to the barrel, you can afford to have one much, much longer and squeeze every ounce of power out of it

yeah i know another barrel is on the way its just all i had at the moment... i will be making about 4-5 barrels for her (maybe more).. different lengths and diameters

hmmm...a fire extinguisher...that's a good idea. i never thought about that before.

NICE CANNON,but lol at the 42yo fire extinguisher ridden with rust spots,,

dont go bumping that thing under pressure

FORE!!!! wrote:NICE CANNON,but lol at the 42yo fire extinguisher ridden with rust spots,,

dont go bumping that thing under pressure

well the tank has no rust only the base... and its gonna be stripped and repainted very soon

ok another double post.. and i did something stupid.. i just dry fire it at about 280 psi (not sure if a sprinkler valve with this pressure is a good idea ) OMG it moved about half a foot under me thats scary... the tank only showed about half in the green (has built in pressure guage) i dont think i'll do that again

Are you in the uk? if so were did you get your sprinkler valve?
I wouldnt trust a sprinkler under that pressure so yes, dont do it again

Ive just noticed something funny.
look on the third pic down and on the right hand side of the fire exstingisher.

nope I'm in aus and i wont try that again it was way to scary lol


"strike knob hard"?

its an old fire extinguisher with a thin copper disk and a pin for the valve you hit the knob and she starts to flow.. it has a trigger in the hose to slow it down but once you hit the know shes all GO!!!

HOLY CRAP!! You put 280 through a sprinkler mate??!! They are normally good for 120 MAX.

That outa the way, where abouts are ya in this fair land.

Hmm looks pretty uncomfortable of awkward to hold. But for a first i guess its ok i dont really like the chamber size as jack stated.