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first coaxial plans

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: jrrdw » Wed Jan 02, 2008 4:40 pm

Wont that union hold the diaphram in one place? Thus not allowing it to move, keeping it from working?
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Unread postAuthor: sandman » Wed Jan 02, 2008 4:44 pm

the diaphragm is flexible so it can stretch, hence why sprinkler valves work :wink:
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Unread postAuthor: jrrdw » Wed Jan 02, 2008 4:50 pm

sandman wrote:the diaphragm is flexible so it can stretch, hence why sprinkler valves work :wink:


Wont it be clamped all the way around? It has to let the pilot chamber vent.
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Unread postAuthor: sandman » Wed Jan 02, 2008 4:57 pm

jrrdw wrote:Wont it be clamped all the way around? It has to let the pilot chamber vent.
a sprinkler valve is clamped all the way around :roll:
and when it vents the force stretches it back and allows the air into the barrel
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Unread postAuthor: BigJon » Wed Jan 02, 2008 5:01 pm

The diaphragm is accually a little bigger than the diameter of the union so it can move back and forth a little bit i think. Kinda hard to explain so sorry if you don't understand.
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Unread postAuthor: Easterbunny » Wed Jan 02, 2008 6:30 pm

would it be easier and peform better to make it a piston insted? somthing like an end cap with a rubber disk , bolt washer and a nut. put a couple of holes in the endcap for airflow. here
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Unread postAuthor: BigJon » Wed Jan 02, 2008 6:34 pm

If you use the piston method you won't need to drill holes in the endcap (piston) unless it is absolutely air tight. I also think a piston would be easier to make but thats just me.
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Unread postAuthor: Easterbunny » Wed Jan 02, 2008 6:35 pm

would this piston work?
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Unread postAuthor: BigJon » Wed Jan 02, 2008 6:41 pm

If you want a piston valve have a look at this since your chamber is 3"http://www.spudfiles.com/forums/3-piston-t313.html
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Unread postAuthor: Easterbunny » Wed Jan 02, 2008 6:49 pm

thank you, how much movment should i allow for it?
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Unread postAuthor: sandman » Wed Jan 02, 2008 6:52 pm

i think the formula is use 1/4 of the diameter of the piston
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Unread postAuthor: MrCrowley » Wed Jan 02, 2008 7:04 pm

Barrel diameter, not piston :wink:
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Unread postAuthor: sandman » Wed Jan 02, 2008 7:13 pm

wouldn't the Piston OD and the Barrel ID be the same thing?
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Unread postAuthor: Easterbunny » Wed Jan 02, 2008 7:14 pm

ok here is the updated plans, i hope to make the body tube removeable to service the launcher if it is nesscary with a pistion
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Unread postAuthor: MrCrowley » Wed Jan 02, 2008 7:16 pm

sandman wrote:wouldn't the Piston OD and the Barrel ID be the same thing?


No otherwise the piston wouldn't work :wink:

And if the piston O.D = Barrel I.D wouldn't the piston go inside the barrel :P

The piston needs an exposed area that has pressure forcing it back, that's why pistons work so well.

So the O.D of the piston could be say 8cm and the I.D of the seat(barrel) could be 7cm.
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