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Piston valve tennis ball cannon Help!

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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Piston valve tennis ball cannon Help!

Unread postAuthor: Chornbeak » Tue Jul 21, 2009 7:12 pm

Well I've been in the process of planning/ building a fairly compact tennis ball cannon with a 4" chamber. Under-over config. I have run into the problem of the valve. I was initially planning on using a 1" modded sprinkler valve, but i decided i wanted higher performance, so i decided to try a piston valve. I am inexperienced with piston valves, but I get the basics of how they function.

On my launcher so far, I have reduced both the 2.5" pipe and the 4" pipe down to 2", but now I need to know what size T and piston size I should use. Also, pros and cons of barrel vs chamber sealing?

btw the reduced 2" is the inside diameter of the reducer bushings, not inside 2" pipe

Any advice, help, or plans for a valve would be greatly appreciated!

btw, yes im new, but not to spud guns, Ive built 6
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Unread postAuthor: Technician1002 » Tue Jul 21, 2009 7:34 pm

Some of the pro and con of chamber vs barrel seal pistons are covered in the wiki.

http://www.spudfiles.com/spud_wiki/index.php/Piston_valve

This covers some of the issues faced from failure to work to performance to reliability. It covers lightly some of the size ratio issues in regards to performance and piston outside diameter vs valve seat diameter. I hope this helps.

This launcher has a 100 yard tennis ball range.
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Attachments
Tennis ball barrel1.jpg
This little 1 inch piston valve tennis ball launcher can launch rolled up t shirts 200 feet.
Tennis ball barrel1.jpg (36.58 KiB) Viewed 1200 times
stadium1.jpg
Range of the shirt launcher overlaid on the stadium where it will be used Aug 8th.
Last edited by Technician1002 on Tue Jul 21, 2009 9:12 pm, edited 1 time in total.
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Unread postAuthor: twizi » Tue Jul 21, 2009 7:55 pm

use a 2inch sprinkler
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Unread postAuthor: jackssmirkingrevenge » Tue Jul 21, 2009 8:32 pm

Have you considered a 4" coaxial? You'd still have a very good chamber:barrel ratio in terms of volume so the power would certainly be there and it would be significantly more compact than an over/under launcher.

btw, yes I'm new, but not to spud guns, I've built 6


This forum has a showcase section for that very reason, welcome to spudfiles ;)
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Unread postAuthor: unisonmind » Tue Jul 21, 2009 8:34 pm

go big or go home--- i would go with a 4'' tee with a 3'' port or a 3'' tee with a 2.5'' port--- like this http://www.spudfiles.com/forums/udtbc-10-my-new-3-piston-valve-t12958.html
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Unread postAuthor: Chornbeak » Tue Jul 21, 2009 11:10 pm

well Ive built 6 actually now that I think about it 7, 2 combustion cannons got confiscated when I used them in Joshua tree natl. park. The rangers really did not like it one bit at all. My first pneumatic was made of bad pvc and cracked after a few pressurizations. My second one, my parents took it away and destroyed it because they caught me shooting paintballs at crows. My third one was a remake of the second, and I have it to this day. 1.5" chamber, .5" barrel, can shoot a .5" ball bearing through .75" pine at 80 psi. My fourth was a 5 foot long behemoth that could launch a tennis ball out of sight. My uncle recently purchased this cannon off me so he could do accurate water balloon artillery on his neighbors. He enjoys figuring out the physics of the whole thing so he can accurately place a water balloon anywhere within a 1/4 mile radius. I'll have to post some pictures
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Unread postAuthor: Chornbeak » Tue Jul 21, 2009 11:28 pm

I dont think im up for a full 3" port, I want to make it a bit more compact

Also, I'm not willing to shell out the cash for a 2" sprinkler valve[/quote]
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Unread postAuthor: Chornbeak » Tue Jul 21, 2009 11:40 pm

Is there still a big advantage from a 1" sprinkler valve to 1.5" port piston valve? Or would that not make too much of a difference?

Also, I'm pretty much stuck with an under over config, I already have the barrel and chamber built. I switched my plans after I started the build.

Also, since my barrel is already reduced to 2", what size fittings should I use to make a 2" barrel sealing valve? What about a 2" chamber sealing one?

Also, I like this configuration shown here

http://antennalaunchers.com/dftv19/

How exactly would that be built?

One more thing, I don't have a lathe, so I'm going to stay away from machined pistons
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Unread postAuthor: jackssmirkingrevenge » Wed Jul 22, 2009 12:07 am

Chornbeak wrote:Is there still a big advantage from a 1" sprinkler valve to 1.5" port piston valve? Or would that not make too much of a difference?


It would make a tremendous difference, for starters the porting is more than double and flow is even better, there's no comparison.

Also, I like this configuration shown here

How exactly would that be built?


Can it be more clear?

Image

No need to go to this level of complication though, construction could be greatly simplified.

One little thing, try to edit your posts instead of posting multiple times ;)
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