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A potential piston design

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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A potential piston design

Unread postAuthor: Pilgrimman » Thu Jul 12, 2007 6:10 pm

This is my first piston idea, as I've never built one, so feedback is appreciated!

I can't animate, so I'll describe it as best I can.

Imagine a coaxial gun. The only difference is the addition of a reservoir behind the seat of the piston. The piston is barrel-sealing. The piston is attached to a metal rod on the back. Around this rod is a spring that holds the piston flush with the barrel. The spring is hooked up to wire and batteries, with a switch. The wire and spring, when charged, moves the piston back like a solenoid. This seals off the reservoir, like clide's GB Semi. When the circuit is broken, the spring reseats the piston against the barrel, and air flows up to the piston and into the chamber again.

This is the basic idea. I'll work out the subtleties some other time, but I want to know if a solenoid piston is even viable, beyond sprinkler valves.

If you have questions, ask 'em!
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Unread postAuthor: jrrdw » Fri Jul 13, 2007 5:18 am

I'm thinking you would need magnets lining the pilot chamber to make that set up work. Also the pilot chamber would need to be big enough to house all the componets, and it would have to be very strong to work against the opposing pressure in the rear storage tank. Off the top of my head, but anything is possible.
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Unread postAuthor: spud yeti » Fri Jul 13, 2007 7:17 am

I thought of the electromagnet idea a while ago, but came to the conclusion that Im not sure if the electromagnet would be strong enough to pull the piston back.
Mine was a bit like this design I just drew: http://s203.photobucket.com/albums/aa95 ... magnet.jpg

Please try drawing your plan in MSPaint even so I can get a better idea of it :oops:
I hope for your sake, your design works!
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really good quote/phrase here
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Unread postAuthor: )DEMON( » Fri Jul 13, 2007 7:49 am

It would work if you do it right.

Here is how I would do it.

1) get rid of the reservoir behind the piston, it is not needed. For this design we let the piston operate mechanically.

2) change the piston design. What we want to do here is make the piston cylindrical and the same diameter as the barrel or as close to it as possible. What we are doing here is eliminating area that will be acted on by the gas pressure to apply force in the direction the piston can move in.

3) seal the piston from the out side of the cannon, this will be done with
o-rings on the piston. We can be sure that with the shape of our piston that it will not be forced open or closed.

4) have the piston extending out the back of the cannon. You can build your electro magnet onto it.

See the drawing if that is hard to swallow, I know I missed some things but the drawing should clear it up.
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Unread postAuthor: Pilgrimman » Fri Jul 13, 2007 2:18 pm

Thanks for the help, everyone! I'll try to do it in MS paint if I have time, but I might not due to the presence of relatives in a little while... :cry: :evil: :cry:

@Demon

The orange in the drawing is the chamber, right?
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Unread postAuthor: )DEMON( » Fri Jul 13, 2007 3:05 pm

Yeh, that's the chamber. You mentioned a co-axial cannon so that's how I drew it. The design should work for a barrel sealing tee as well.
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