Best way to dump air from 2 resevoirs?

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Mihlrad
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Mon Jul 10, 2006 11:29 am

building my pnuematic cannon and it consists of two 36" long by 4" diameter pipes for resevoirs, my question is what would be the best way for me to dump the air into the barrel from these two resevoirs? A supah valve is just simply out of the question due to price but im open to basically all other suggestions, my current plan was to use 2 sprinkler valves and hose them together onto a single blowgun, but i was wondering if there was a more effective way that would give me a nice boost in power over using sprinkler valves. Thanks in advance.
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CS
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Mon Jul 10, 2006 11:35 am

Have you looked into piston valves? Im sorry but I laugh everytime I see one rig up these huge chambers and push there contents threw ditzy sprinklers. Attempt at some 4" T config pistons.
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Mihlrad
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Mon Jul 10, 2006 11:38 am

there is a video somewhere on how to make a piston right? I honestly never used anything but a ball or sprinkler valve so it would be very new to me.
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huse_spud
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Mon Jul 10, 2006 11:48 am

Mihlrad wrote:there is a video somewhere on how to make a piston right? I honestly never used anything but a ball or sprinkler valve so it would be very new to me.
just put like 4 modded sprinklers on each chamber, that'd be screwed up.

my big dumbass launcher only has one sprinkler on it, but i launch soda bottles like 200 yards which is fairly good (i retrieve the bottles to determine the distance the best i can).

the trick is to pack them mutherfuckers in there tight with towels so they have to kick the hell out of there. it works pretty well.
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Mihlrad
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Mon Jul 10, 2006 12:20 pm

ok well i just watched the tutorial on how to make a piston valve and i dont quite understand it exactly, what is the ball valve on the end of it for? Where do i connect the resevoir and the barrel to? I just dont understand how it works.... also can i use leftover springs from broken watermasters for the spring it needs? O yea also what does he use for his "piece of rubber" ?
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WOW!!
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Mon Jul 10, 2006 1:23 pm

You can make a piston vavle out of a 4" tee.
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huse_spud
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Mon Jul 10, 2006 1:44 pm

Mihlrad wrote:ok well i just watched the tutorial on how to make a piston valve and i dont quite understand it exactly, what is the ball valve on the end of it for? Where do i connect the resevoir and the barrel to? I just dont understand how it works.... also can i use leftover springs from broken watermasters for the spring it needs? O yea also what does he use for his "piece of rubber" ?
the ball valve is prolly the pilot, you seem very cornfused, just do what ur good at and use sprinklers til u figure it out (plus 4 inch tees prolly cost more than a sprinkler valves anyways)
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Velocity
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Mon Jul 10, 2006 1:49 pm

Yeah, you really do need a large valve to use on this cannon... I have a cannon of similar size (only 12" longer in each chamber), and I used dual supah valves. Two 1" sprinkler valves are out of the question. Using two 1.5" sprinkler valves would be improvement, but still would yield poor(er) performance. Dual 2" sprinkler valves pneumatically actuated should work well.

The reason I am not advocating a piston valve right now is because it is not easy to comprehend and then build a working one. Even so, you should start off relatively small building a piston valve (if you were going to attempt one at all) before you attempt the big 4" piston valve
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benstern
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Mon Jul 10, 2006 1:54 pm

Use a Burst disc! It is the fastest way. Also, it is very easy.
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Mihlrad
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Mon Jul 10, 2006 3:18 pm

i think im going to try to build a 2" set of 2 piston valves, anything over 2 inch is jacked up price wise. I may do 3 but i doubt it, i spoke with BC and he talked me threw my questions so i should be able to make it if not ho me depot will have some interesting returns.



Also would i be better off using 2 resevoirs 2 feet in length or should i stick with the 3 foot resevoirs?
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noname
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Mon Jul 10, 2006 6:44 pm

Just keep it 3, the power will be more and it won't cost a whole lot more. And I'd use either 1.5" sprinklers, 2" pistons or a 2" burst disk. Burst Disks are the easiest, cheapest, and you can make them hold as much pressure as you want pretty much.
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carlbelcher
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Mon Jul 10, 2006 8:20 pm

The problem with bust discs is that you can't really control when they are going to fire, and if I'm not mistaken mihlrad is building a backpack style cannon using burst discs would totally screw over the portability.
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noname
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Mon Jul 10, 2006 9:50 pm

That''s not true. Just run a hose from the tanks to the union.
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carlbelcher
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Mon Jul 10, 2006 10:20 pm

noname you're missing the point! I'm not saying that the burst disc is not portable! I'm saying that the to the burst disc fires at a set pressure so you can't charge the gun then walk around with it before firing. You would have to have ether a hand pump (which would suck with this big of a chamber) or be tied to a compressor hose while shooting the cannon.
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Mihlrad
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Tue Jul 11, 2006 7:31 am

Does a piston made of hot glue actually work well? Or is there a better alternative to hot glue for the piston that the common person can make or buy. (in the video tutorial BC uses hot glue and molds it in a coupler) Also what should i use for the thing at the end, top of a cofee container?
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