Semi Auto

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.
clide
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Fri Apr 20, 2007 3:17 pm

The limiting factor is my air supply. I built a high flow check valve into the piston and the 3-way exhaust valve has a high flow through it to minimize filling times, so if I had a high enough flow air source I could probably get a significantly faster ROF.

The video misrepresents the sound. It sounds like it is getting a lot quitter and having troubles, but I think that is just an auto sound dampening on the camcorder kicking in. Its been awhile since I fired it, but I'm pretty sure it sounds more consistent throughout all the shots in real life. I don't think I would start having any issues until below 30 psi, but I never even really bothered to try it that low.
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bboymatty
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Mon Apr 23, 2007 7:29 am

what a fantastic design, absolutely love it to bits. great work.
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ALIHISGREAT
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Fri Sep 07, 2007 3:23 pm

awesome cannon, i like the fact you have made the valve AND pilot yourself and they are a cool design.
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The Kid
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Sat Sep 29, 2007 9:47 am

that cannon is a work of art i never would have thought of anything like that (in fact i never think of anything i am very unoriginal)
Gepard
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Sat Sep 29, 2007 9:49 am

Please stop posting to old topics unless you have something useful to add.
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Hailfire753
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Sat Oct 06, 2007 1:34 pm

Ok, well I hope this is useful...

If I were to modify these designs to fit in a sniper-rifle esque design, I would want to use it in a painball match. How would I adjust the fps the gun pounds out? Would I increase the spring tension of the loading mech, or decrease the chamber pressure?

I would want to use regulated C02, how much would it cost for an ajustable regulator and hook up? (quick disconect)

Also, with your RoF, if you pressed the trigger faster why wouldn't it increase? If there is less time in between shots, wouldn't the chamber psi only be less? As long as the loading mech supplies panitballs fast enough, wouldn't it still shoot?
Last edited by Hailfire753 on Sat Oct 06, 2007 1:37 pm, edited 1 time in total.
UPDATED MARCH '08
field-legal paintball semi
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VH_man
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Sat Oct 06, 2007 1:37 pm

you would decrease the chamber pressure.......
clide
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Sat Oct 06, 2007 4:17 pm

Yes, as VH said you would just decrease the chamber pressure to reduce the speed. Also, yes my gun was limited in ROF by the fill speed and also a bit by the fact that the trigger pull is relatively long. I probably couldn't pull it faster than about 4 RPS and it would probably be inconsistent at that speed because of the fill rate. But that could be fixed by a higher flow rate air source or maybe a on board secondary chamber that holds some air for the refill.
lilazndogg940
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Sat Sep 27, 2008 10:32 pm

Hey so how does the piston valve body pop back. does it pop back because the pressure is realeased behind it or wat i dont get how it does it
clide
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Sun Sep 28, 2008 6:43 pm

The valve works like a normal barrel sealing tee valve. Here is a thread that explains piston valves http://www.spudfiles.com/forums/piston- ... t8157.html
<a href="http://gbcannon.com" target="_blank"><img src="http://gbcannon.com/pics/misc/pixel.png" border="0"></a>latest update - debut of the cardapult
SEAKING9006
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Mon Sep 29, 2008 9:24 pm

I apologize for bumping, but I'd love a video, current link is broken.
Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)
clide
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Mon Sep 29, 2008 10:02 pm

Somebody put it on youtube here
<a href="http://gbcannon.com" target="_blank"><img src="http://gbcannon.com/pics/misc/pixel.png" border="0"></a>latest update - debut of the cardapult
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FordGtMan
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Mon Sep 29, 2008 10:06 pm

Wow, impressive video. Too bad all those damned idiots on youtube think that the whole deal was a real paintball gun as the gun wasn't showed. :x
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chrissilvermancs
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Sat Mar 14, 2009 12:36 am

..........
Last edited by chrissilvermancs on Tue Jun 08, 2021 12:14 am, edited 1 time in total.
clide
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Sat Mar 14, 2009 10:18 pm

Look at my last post a few posts up for the video.

It doesn't waste a ton of air, but it's not the most efficient thing either. I haven't fired it in a long time but I believe it got around 13 shots before the compressor had to kick on. So based on memory I think that would be a 5 gallon tank from 100 to 70 psi.

I haven't really fired the gun much so I can't really say about the maintenance. I would guess that it would need more maintenance than a commercial paintball gun.
<a href="http://gbcannon.com" target="_blank"><img src="http://gbcannon.com/pics/misc/pixel.png" border="0"></a>latest update - debut of the cardapult
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