Piston based air machine gun

[mako]

Hey, guys, I've been looking around, trying to figure out the easiest, most efficient BB machine gun for air-soft.

After much deliberation, I came up with this idea.
Using a gasoline engine base design, the cam would move a piston against a hammer valve, and back away again. This would release a burst of air, which would go through a hole in the piston head. A tube of the proper diameter would be in the hole, catching the air and firing the BB.

Any type of magazine could be attached to this, and with a properly geared electric motor, fairly high pressures could be used. Alternatively, you could use a hand crank. This design might also lend itself to a Gatling gun with real rotating barrels.

Thoughts?

PS. JSR, this would be the perfect piston to make out of epoxy.
(*warning* pressures below 850 PSI ONLY)

[sagthegreat]

this just gave me the idea of an coxial pengun, where the piston draws bbs into the barrel before its piloted, using the magazine as a part of the chamber

[mako]

hey, glad to help with new ideas. Any thoughts on how well this might work?

[jackssmirkingrevenge]

*warning* pressures below 850 PSI ONLY

Ah, the eternal fascination of reciprocating mechanisms. Some recommended reading, young grasshopper:

http://www.spudfiles.com/forums/electro ... 10746.html

http://www.spudfiles.com/forums/full-au ... 11923.html

http://www.spudfiles.com/forums/electro ... 22259.html

http://www.spudfiles.com/forums/jacks-s ... t7361.html

http://www.spudfiles.com/forums/making- ... 12899.html

Long is the way, and hard, that out of hell leads up to light.

[Technician1002]

I have to laugh at the OP graphic. The surface area on the piston vs the surface area of the piston. I suspect at the pressures suggested, the piston could pass the projectile to the target.

On the other hand by modifying the cam on a small gas engine such as a 4 stroke lawnmower, it could be used as a compressor, and the exhaust valve could open at top center to release bursts of compressed air. It would take a larger engine to push it. A typical ~6:1 gas engine could provide bursts at about 50 PSI.

[mako]

Hey, JSR, thanks for the links, they were very helpful. I'd never seen them before on here.

@Tech1002, given that this is for air-soft, the pressures necessary would be quite low. If I had a high pressure air supply, I'd regulate it down. The 850 PSI was a joke for JSR.

However, the piston would not be sealed from the outside. It would have a hole in it going to the barrel, so not much pressure would act on it. Also, a correctly geared electric motor would be capable of reaching the proper pressures.

In regards to the gas engine design, that is essentially how a spring piston works, but with much more abrupt force. I've built the spring gun, but now I want full auto. 8)

[jackssmirkingrevenge]

What I don't like about this design is that it opens the valve at the speed of the piston. It's better to have something spring loaded driven by an eccentric cam (a bit like the piston on an electric gun) to act like a true hammer.

I've built the spring gun, but now I want full auto.

You don't need to involve electrics.

http://www.spudfiles.com/forums/qevandp ... 17810.html