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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.
PracticallySane
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Sun Dec 27, 2020 10:42 am

Also it is a barrel sealing piston. The "face" sits inside the barrel instead of pressing up against it. The rear oring is a "floating oring" so air passes one way to fill the chamber. It cannot flow in reverse.
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hectmarr
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Sun Dec 27, 2020 7:18 pm

PracticallySane wrote:
Sun Dec 27, 2020 10:42 am
Also it is a barrel sealing piston. The "face" sits inside the barrel instead of pressing up against it. The rear oring is a "floating oring" so air passes one way to fill the chamber. It cannot flow in reverse.
His drawing is very clear, which is worth ten thousand words! THANKS! :)
The barrel side oring is what seals. I like the concept, because it is simple.
The "floating o'ring" lets air pass from the exhaust valve on the right to the main air chamber on the left and below.
Thanks for the drawing. In the future I will try to do something with this idea, a hybrid for sure.
Ideas don't make holes. The weapons yes! ;)
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hectmarr
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Fri Jan 01, 2021 8:00 pm

I built a valve like the one you use, but very small, it is for a future hybrid short gun. It works wonders and I no longer have the problem of burning the front seal, nor doing it, nor aligning it absolutely perpendicular to the barrel so that it seals. The smaller diameter is only 6.35mm and the larger piston is 8mm. I only bought about 50 6mm o'rings, which are what I used in the part that seals the combustion chamber. Add a system so that the pilot is open after the shot, because I need air to be able to come out of the barrel to clean the chamber immediately after the shot. It has a stem to close it before pressurizing with butane and air. When I can, I'll leave some photos here.
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hectmarr
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Fri Jan 01, 2021 8:59 pm

válvula de sello con oring.png
válvula de sello con oring.png (16.95 KiB) Viewed 200 times
This is the drawing of what I built.
Ideas don't make holes. The weapons yes! ;)
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hectmarr
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Sun Jan 03, 2021 2:55 pm

A photograph of how it was. I am building a mechanism so that it closes automatically. The small piston with two o'rings and the hole in the center is for decompressing. It is fiberglass because it only supports 6 or 7X pressure. The hard part is the one that seals the chamber.
I leave here in this publication what I did, because I think it is not necessary to make a new topic, it is a comment of the same.
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PracticallySane
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Sun Jan 03, 2021 4:33 pm

Its very interesting, I like hybrids mostly for their power. When I make things with repeating or automatic operation I like to use HPA it is easier to achieve reliability and consistency in my experience.
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hectmarr
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Sun Jan 03, 2021 10:11 pm

Yes, using a high pressure tank is more comfortable and faster than pumping, but in my city these things are very expensive. Likewise, I have a co2 reservoir, which I can fill with air up to 900 psi, and I use a reconditioned pressure regulator, which is from an oxygen tube. It admits up to 200 bar at the inlet and regulates from 0 to 15 bar at the outlet. It's a bit bulky but it's what I could afford. An HPA bottle with an airsoft regulator costs two my monthly salaries, and is not an option. Apart from that, there is not, I have to import and here it is very expensive. What I built with the 500 cm3 CO2 tube and the oxygen regulator, gives me 50 shots with my 7X semi-automatic hybrid, little more little less. The air is pumped with a 300 bar PCP type inflator.
We must look for solutions, although not ideal, possible.
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hectmarr
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Mon Jan 04, 2021 6:10 am

Add what was missing to get the valve closed automatically. It works correctly, luckily. The valve closes when you let in compressed air and the pilot depressurizes immediately after firing.
The dosing system that I am testing needs to be able to decompress to measure the right amount of butane, it is of the volumetric type. I'm thinking of adding a 60cm firing cannon, with 12 microstriae that I bought a long time ago, caliber .25, and firing ordinary pellets 8-)
Válvula a pistón con piloto y despresurización y cierre automático.png
Ideas don't make holes. The weapons yes! ;)
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