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full auto questions

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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wat do you think

might work
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should work
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not going to work
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Total votes : 2
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full auto questions

Unread postAuthor: cannon monkey » Fri Jun 05, 2009 3:08 pm

ok im not too good with all of this i ran into this
http://www.spudfiles.com/forums/how-to- ... 14427.html
and the first picture made me think

<a href="http://s119.photobucket.com/albums/o124/monkey083192/?action=view&current=Untitled.jpg" target="_blank"><img src="http://i119.photobucket.com/albums/o124/monkey083192/Untitled.jpg" border="0" alt="full atuo idea"></a>


air gets filled into the chamber once around 115 the pop valve opens pushes the bolt up closing the feed and firing
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Unread postAuthor: spot » Fri Jun 05, 2009 4:41 pm

I think this design has a reasonable chance of working (It's always hard to predict :S). You will want to make sure though that the bolt is a little bit longer, so that the magazine is shut off when air can pass through. also make sure the bolt seals in front of the port, so that air trapped in the chamber of the pop-off can escape through the barrel. Otherwise it won't cycle.
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Unread postAuthor: cannon monkey » Fri Jun 05, 2009 4:43 pm

:D when i get money i might try ( this my plans for my 5th cannon...)
unless sombody else has parts and cash now.... i wont mind i think it might work
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Unread postAuthor: SEAKING9006 » Fri Jun 05, 2009 5:18 pm

It looks just like the configuration developed in my X-ACS project. The thread is lying around here, somewhere. It was a thru-bolt design with a large tank with a tube running through it. This tube had two sets of holes, one in back and one near the front. There would be a piston rod in this tube, sealing off all holes. A sprinkler valve at the back of the gun would open, pushing the sealed rear of this piston foreward until the rear cleared the rear slots, allowing the large chamber of air to also push on it. It would then keep going foreward until slots on the rod came up to the tubes foreward holes, allowing chamber pressure to vent into the rod and out its front. The rod would also act as the bolt, chambering a golf ball. Even if you don't use my design, I have a bunch of calculations done for it and I have a list of springs you might want to try.
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Unread postAuthor: THUNDERLORD » Fri Jun 05, 2009 7:48 pm

It might work, but not like the diagram, the bolt would vent into the magazine if the drawing was to scale.
I was thinking rather than a "T" it would have a flow regulator (like a ball valve constricting the flow but not pressure) adding pressure behind the bolt,
and a larger unregulated flow into the chamber.
Maybe two reservoirs, with higher pressure tank entering behind the bolt.
Also the bolt might need to leak a little (fit loosely at the front) so it would reseat.
It looks like it would require a lot or too much fiddling to vent the entire chamber before the bolt resets.
The weak point is that the bolt needs to hold the same pressure as the barrel (in that diagram) and that will constrict the flow.
Unless the bolt is same/ larger than the projectile, then it gets to be a pain... :roll: ...My piston BFB design...same issues...but less fiddling...still alot of fiddling...
still less fiddling than changing Harley-Davidson rims with 50 stupid puzzle piece fittings each for a particular wheel, while holding everything grease covered... I cuss at him so much he might kill me on the highway for spite! ...My damn Thunderhorse :P :evil: 8)

EDIT:Just looked over the pop-off again, looks like less fiddling than I first thought. Confused though whether it would vent the whole chamber, and if the pressure behind the bolt will drop enough to reseat the bolt (still thinking the bolt should fit loose). It could probably work IMO.
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Unread postAuthor: jackssmirkingrevenge » Sat Jun 06, 2009 2:02 am

Roughly what I did here ;)
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Unread postAuthor: spot » Sat Jun 06, 2009 6:57 am

To Thunderlord: I already suggested to make the bolt longer, so that it doesn't leak in the magazine. And the bolt HAS to seal, otherwise the chamber will keep leaking through the bolt. But, as I said it has to seal in front of the port, so that the air that remains in the pop-off tube can leak through the barrel.
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