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Building a new cannon
Posted: Tue Dec 23, 2008 6:56 pm
by maggotman
Posted: Tue Dec 23, 2008 7:05 pm
by starman
That's a really beastly setup you have there. If you have the piston dialed in, it should be a very good performer as well.
What plans do you have for ammo, barrel length etc?
Posted: Tue Dec 23, 2008 7:06 pm
by psycix
Looking good! Complete the black paint job on the chamber.
I like the shiny new fittings!
-What are you going to use as piston?
-Do you trust your welding job enough for high pressures?
Posted: Tue Dec 23, 2008 8:02 pm
by Cosmic Muffin
that thing looks like it could put a fair hole in someone...
you could get a whole lot of power for it too, cos your using a high pressure bottle, could take it up to around 400 psi?
Starman would know, haha hes like a bloody walking encyclopedia.
but yeh looks good. pilot the piston with a modded solenoid valve and she'll be a beauty.

Posted: Tue Dec 23, 2008 8:23 pm
by maggotman
psycix wrote:
-What are you going to use as piston?
-Do you trust your welding job enough for high pressures?
the paint was just to stop it going rusty will paint it when finished
unsure of the piston i did have an old bike piston out of my bike but it is f**ked from slamming into the end cap
i have filled it with water and pumped it up to 350 with a shock pump
and it did not fail i got good penetration wen i welded it and went over it 3 times
i plan to vent the valve with another one like this

Posted: Thu Dec 25, 2008 7:06 am
by psycix
What will the operating pressure be?
You should test it to at least 150% the operating pressure if you want to be safe. 200% or higher would even be better
but it is f**ked from slamming into the end cap
You had a bumper?
Posted: Thu Dec 25, 2008 2:39 pm
by SP00K
Lol, looks good, but still looks pretty ghetto.
Posted: Thu Dec 25, 2008 3:02 pm
by maggotman
i did not have a bumper
i have now got a fridge compressor so can it up to 600psi
providing the welds are stronger than the material what would any of you say it would take the brass fittings the tank? i could fill it up to 600psi if i wanted
but i think the police would be around my house pity darn fast if i let it off and
Posted: Fri Dec 26, 2008 7:10 am
by maggotman
fired it today it was crap i think the culprit is the piston valve ?
Posted: Fri Dec 26, 2008 10:52 am
by ALIHISGREAT
maggotman wrote:fired it today it was crap i think the culprit is the piston valve ?
we'll need pics of the piston, it could be the pilot too, i reckon to get good performance, you'll need a 1/2" QEV to pilot.
Posted: Fri Dec 26, 2008 1:57 pm
by maggotman
found the culprit air was leaking around the piston
washes and nuts and bolts i ditched that idea ive cast a piston out of 2017 arodite should i fill any dead space behind the piston or not bother ?
Posted: Fri Dec 26, 2008 2:15 pm
by Moonbogg
LOL thats a friggin total beast. Awesome. Also, I wish I was good at welding. I know how as I took classes, but...
Posted: Fri Dec 26, 2008 2:48 pm
by ALIHISGREAT
maggotman wrote:found the culprit air was leaking around the piston
washes and nuts and bolts i ditched that idea ive cast a piston out of 2017 arodite should i fill any dead space behind the piston or not bother ?
you could fill some excess pilot volume with a bumper.
Posted: Fri Dec 26, 2008 5:51 pm
by maggotman
Moonbogg wrote:LOL thats a friggin total beast. Awesome. Also, I wish I was good at welding. I know how as I took classes, but...
i got a stick welder when i was 16 my mum wouldn't let me have one before ive just turned 17 but i still find it hard if ime not in the right mood or it turns out ugly and loads of slag inclusions
i think ive found the perfect bumper
has any one got any ideas what the max pressure the brass fittings would take
the gass tank its good up to 35 bar 500psi ish so it says and is in good condition no rust
i will probably have the trigger on a hose or use a solenoid valve and incorporate one for filling aswell
one of my pices of ammo 25mm hot rolled bar it is about 0.5kg
some tape will be in order to achive a better fit in the barrel

Posted: Fri Dec 26, 2008 8:12 pm
by potatoflinger
I think your problem is the pilot, that blowgun is probably not a good enough pilot valve. As was already mentioned above, you should upgrade to a QEV or small piston valve as a pilot.