Just talking out of my butt here...

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Intel Xeon
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Wed Mar 28, 2007 8:42 pm

Okay, so I was thinking of redirecting the expanding gas from the firing to drive a spring loaded bolt on the bottom, near the end of, the barrel that would pressurize an auxiliary chamber on the downswing and when swinging up, Close the primary -> Aux chamber connection.

Some immediate problems that I see with this, need for one bigass primary chamber, and somehow having the aux chamber pressurize adequately during the swing meanwhile having enough spring tension to close the valve.

The firing could be controlled by a trigger or somehow worked into one of the swing phases of the bolt.

Ideas?
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c19o
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Wed Mar 28, 2007 8:47 pm

I dont get it, but is your idea is to close a ball valve after its fired? Or close it before all the air goes out? I'm confused.
Intel Xeon
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Wed Mar 28, 2007 8:52 pm

The primary and aux chambers would be connected by some valve, whether butterfly or ball. It would have some form of equalization hole that would have to dispense enough air before the spring pulls the valve shut.
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c19o
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Wed Mar 28, 2007 8:56 pm

I would go with a piston valve.
Intel Xeon
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Wed Mar 28, 2007 8:59 pm

well, a piston seems like overkill for just pressurizing a second chamber, but please elaborate. if you mean for the actual firing trigger, then it might respond too slow for semi-auto fire.
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c19o
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Wed Mar 28, 2007 9:36 pm

No, I mean a piston valve as the main valve. I can hook up my piston valve (1.5" porting), and my coaxial marble gun to a quick disconnect from an air compressor. Then just flick the ball valve open and closed and the gun fires and refills pretty fast my marble gun can get off a shot a second when my compressors filled up. ( not actually firing marbles, just air. But my piston It would work well with semi-automatic system where the air from the firing blows a bolt or something like that to uncover a spring-loaded breech which loads more ammo.
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