Full Auto Marble Gun

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.
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frankrede
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Tue Dec 19, 2006 12:19 am

I dont understand his filling and firing mechanism thing.
Wouldnt the pilot be constantly be pressurized if you were hooked up to the air constantly?
Current project: Afghanistan deployment
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mark.f
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Tue Dec 19, 2006 6:51 am

He probably got it of McMaster im not sure so don't hold me to it, I do know you can get them of McMaster on page 913 or something
Yep. 1/2" Q.E.V. with 3/4" exhaust. I get all my Q.E.V.'s from McMaster. Not just for cannons, but for air cylinders as well. Let's just put it this way, when you hook a single-acting cylinder up to a three way control valve, you have a nice pneumatic piston that can move things with ease. When you hook a single-acting cylinder to a Q.E.V. that dumps right into the thing after piloting... you have a RAM! 8)
I dont understand his filling and firing mechanism thing.
Wouldnt the pilot be constantly be pressurized if you were hooked up to the air constantly?
No. If the blowgun is open, pressure is not allowed to build to the pressure of the IN port, creating a pressure differential, firing the valve.

If you read in my other cannon's thread, (Revamped), I salvaged this cannon because it was no fun anymore. Thing was scary when it worked, though.
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Dan003400
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Sat Dec 23, 2006 3:37 pm

How does the load system work???
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mark.f
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Sat Dec 23, 2006 9:37 pm

Interrupted gravity feed. Paddle interrupts the feed of marbles when the valve exhausts.
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Dan003400
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Sun Dec 24, 2006 4:19 am

I dont understand how the loading system works, what is in the T?
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mark.f
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Sun Dec 24, 2006 8:27 am

The paddle. It swings up when the valve exhausts.
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zeigs spud
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Tue Jan 09, 2007 9:27 pm

neat. in the vid it looked as if the cannon shot high tho.
how much did that metal sprinkler valve cost tho :shock: it must been a butt load and how many psi can it take?

Dan003400 wrote:I dont understand how the loading system works, what is in the T?
the "T" is the loading system. the ammo sits ontop of other ammo and is sucked into the barrel and shot out. atleast if thats the "T" i think ur talkin about.
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mark.f
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Tue Jan 09, 2007 11:07 pm

Valve was only about 18 bucks, actually. And yes, I did hold a little high for those shots.
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MrCrowley
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Wed Jan 10, 2007 12:16 am

zeigs spud wrote:neat. in the vid it looked as if the cannon shot high tho.
how much did that metal sprinkler valve cost tho :shock: it must been a butt load and how many psi can it take?

Dan003400 wrote:I dont understand how the loading system works, what is in the T?
the "T" is the loading system. the ammo sits ontop of other ammo and is sucked into the barrel and shot out. atleast if thats the "T" i think ur talkin about.
He meant how did the paddle work inside the tee. Anyone knows about gravity feed hoppers....And the ammo shouldnt be sucked out of the tee it should be pushed out,if its sucked out that means the paddle didnt work and 2 marbles were in the breach instead of one...

And that metal sprinkler valve is called a QEV
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mopherman
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Fri Mar 09, 2007 10:05 pm

sorry to dredge up an old topic, but is that galvanised steel for the chamber? i thought you couldnt skrew galvanised into a qev.
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zeigs spud
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Fri Mar 09, 2007 10:07 pm

lol why couldent you if it had the right threads?
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mopherman
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Fri Mar 09, 2007 10:10 pm

just some weird idea that came up while i was half asleep.
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mark.f
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Sat Mar 10, 2007 9:35 am

Most Q.E.V.'s I've seen, (disregarding tiny ones with 10-32 ports), have standard NPT pipe thread ports on them. This one has a 1/2" IN port, 1/2" CYLINDER port, and 3/4" EXHAUST port. So all I had to do was use a 3/4" x 1/2" reducing coupling after the chamber and then a 1/2" street elbow and a nipple to connect the chamber to the exhaust valve.
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mopherman
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Sat Mar 10, 2007 9:43 am

is the exhaust por the one with the barrel?
sorry im new to qevs
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VH_man
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Sat Mar 10, 2007 9:49 am

Yes, it is the one it exhaust from. Also, for the maker of this cannon, does that saftey pop valve move back at least a millimeter or two when fired? i think i might steal your idea and use it in an airosft gun....... with a blowback mechaninsm powered by the saftey pop valve.
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