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Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: fireman565 » Mon Feb 25, 2008 3:36 pm

Jared Haehnel...

By far building your own valve is a great feeling, plus the added performance over sprinkler valves. Before you dive off into buying parts, read as much on this as possible before starting on a pistion of that size. Going for a 4" piston is great, but it seems a little harder to find interchangable parts, as in I know a 2-1/2" coupling fits great inside a 3" tee, and a 3" cap will fit near perfectly inside a 4" tee. AND since you work at ACE, mixing and matching shouldn't be too much of a problem on your lunch break.

I just completed a 3" barrel-sealing tee with a 2" port. Its amazing the difference compared to a 1" sprinkler valve. JUST read and study the link you were given. I missed picking up on some info that would have saved me alot of trouble, frontal pressure on the piston once charged. I didn't have any. The gun fired, but when I increased the frontal pressure, the gun FIRED. I built the piston that goes with a 4" chamber 48" long with, right now, a 5 ft. 2" barrel, interchangable with a 1" 5 ft. barrel. I know that's overkill until I get around to dragging in a 10 ft piece. From using GGDT, its pretty simple to figure out that a 1.5" barrel will get you more distance than a 2", at least with my design.

This sounds old, just read everything offered here on the piston valves. They're simple to build, just not as forgiving as throwing together a combustion launcher, or a pneumatic working off of a sprinkler valve. More human factors to troubleshoot.
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Unread postAuthor: Jared Haehnel » Mon Feb 25, 2008 3:47 pm

Hey thanks for the adivice I've been doing a bunch of reading in the forums and it awesome how much information is offered you guys are great. I love GGDT.

Right now its a matter of deciding what materials to go with... I'm hoping to biuld it so I can do a fair amount of experimentation with the design of the valve...

Right I'm working on seeing what other used. It would be helpful if people posted what didn't work so I don't repeat the same mistakes.

I love my hobby :D
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Unread postAuthor: fireman565 » Mon Feb 25, 2008 4:13 pm

I wish I had taken the time to learn more about GGDT before I built this last pneumatic. I now know a 4"x48" chamber with a 3" piston valve for a 2" barrel is too much. I could have gone with one half that size and achieved the same output. The overall size, including barrel length, will be more of a factor on the next one. Two 4"x5 ft. chambers seems like sooo much volume and not enough barrel.

I'm trying to determine now if I could use two 1" sprinkler valves and get the same effect with my 3" piston valve, with two smaller 16"-24" chambers and a 7ft. barrel. Faster to construct for me. I'm not into the 'satifaction' of making my own valve as to the 'satifaction' of launching a spud a quarter of a mile across the river with plumbing parts!
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Unread postAuthor: Jared Haehnel » Tue Feb 26, 2008 7:19 am

I agree... for a two inch barrel anyway. I plan on having a wide variety of barrels and wanted to make sure that I could get good preformace out of a 4" barrel and even a 6" barrel. I'm still playing around with some of the figures in GGDT to determined the right dimensions of the chambers.

My original challenge was to make a cannon that could launch a soda can full of soda eight hundred yards out of 3" barrel. But after entering the numbers into GGDT I realized it was a bit more of a cannon then I wanted to build. The design I've got now could potentially launch one pretty near 600 - seven hundred yards.

GGDT recommends on heck of along barrel to go with those two 4" five foot chambers... The chabmers may very well end up being smaller.

Thanks for the consideration
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