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| hubb017 |
 Posted: 11/08/2007 17:47 PM Post subject: Semi-Auto (or Full Auto?) Piston Valve |
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Sarcasmo
Joined: 28 May 2007
Posts: 1475
584.33 Spud Bux
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The title explains it. First a picture:
Note that the pilot is located to the side (or rear, whatever) instead of in the back as on a conventional piston valve. When the pilot volume is exhausted, the piston slides back, as in a conventional piston. There is an o-ring on the rear of the piston. Once the piston crosses over the pilot area, it is closed off. The spring then resets the piston, causing the pilot to refill for the next shot.
In theory, if all the pieces are lined up correctly, I don't see why this can't be made into a full auto piston valve.
Of course, the image is just a rough sketch. Shortly, I will post an animation showing more detail to help better explain.
Last edited by hubb017 on 11/09/2007 2:40 AM; edited 1 time in total |
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| hubb017 |
| Posted: 11/08/2007 17:48 PM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1475
584.33 Spud Bux
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Last edited by hubb017 on 11/09/2007 1:34 AM; edited 1 time in total |
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| octane89 |
| Posted: 11/08/2007 21:30 PM Post subject: |
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1st Lieutenant
Joined: 11 Sep 2007
Posts: 273
224.26 Spud Bux
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| To me it looks like a normal tee valve. I have been wrong before though. Im sure the animation will explain it more though. I give you props for making an attempt of this though, regardless if it will work or not.
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| hubb017 |
| Posted: 11/08/2007 22:02 PM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1475
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It is a normal tee-piston. The only difference is the pilot exhaust location. With the assistance of the spring, the piston will shut off the pilot and reset. If the "trigger" is held down, it will exhaust the pilot again, causing the piston to open again.
As of now, this is just theory, as calculations and such are going to be needed to get it to work properly. If anything, it is a start to something nice and new and neat. 
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| ShowNoMercy |
| Posted: 11/08/2007 22:11 PM Post subject: |
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Brigadier General
Joined: 19 Mar 2007
Posts: 1119
40.29 Spud Bux
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| Why not try and extend your sealing face to also include something to load rounds?
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| Hotwired |
| Posted: 11/08/2007 23:08 PM Post subject: |
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UK Spudgunner
Joined: 13 Oct 2006
Posts: 1800
3889.01 Spud Bux
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I'm not diggin' the idea 
You will still need 3-way valve/valve assembly on the pilot to exhaust and fill.
...and with that, a normal piston valve would do the same thing
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| jackssmirkingrevenge |
| Posted: 11/08/2007 23:17 PM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6981
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Interesting, I had sketched something like the attachment once but never got round to building it as I wasn't sure the whole piston resetting thing would work. It might merit a prototype...
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| Thursto |
| Posted: 11/08/2007 23:31 PM Post subject: |
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Major
Joined: 02 Mar 2007
Posts: 390
756.42 Spud Bux
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| ShowNoMercy wrote: | | Why not try and extend your sealing face to also include something to load rounds? |
Well i waqs going to start a drawing but jacks got it perfect, that would work, its like your semi auto gun jack (BB gun, the one you attached to the nailgun) the one in the syringe tube
I think that design could work, but you'd have to get the right size spring, and i dont think the o-ring would seal the exuast hole though.
~ Thursto
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| Novacastrian |
| Posted: 11/08/2007 23:36 PM Post subject: |
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Bloody Aussie
Joined: 11 Aug 2007
Posts: 1622
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This design should work very well, getting the correct spring for different pressures would be a challange, as would the design of the internal pilot hole. Maybe if you had a flat face on the back of the piston (horizontal) with an oring fitted on top of the pilot hole, instead of the oring groove around the piston, like a breech seal on a airifle, only this would slide over the pilot hole.
Hope that made sense.
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| jackssmirkingrevenge |
| Posted: 11/08/2007 23:45 PM Post subject: |
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space monkey
Joined: 15 Mar 2007
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hmmm... a square piston, perhaps? It would still have to be servicable though as that o-ring would wear out pretty quickly rubbing against the rear edge of the piston.
btw I only noticed now your small modification of the seven Ps lolol, so, so true 
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| hubb017 |
| Posted: 11/08/2007 23:55 PM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1475
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Nova has the right idea. When the pilot is exhausted, the piston moves back and covers the pilot exhaust, letting no more air out of the pilot area. The round is launched, the spring resets the piston, and the cycle begins again. If the pilot hole in the piston is of the correct size, the "trigger" can be held down and rapid fire obtained.
Something els that can be considered: What if the spring was removed? This would allow the piston to stay in place over the pilot hole until a certain pressure is obtained in the pilot area. This increase in pressure would reset the piston. Of course, this method would cause it to be filled from the pilot area.
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| c19o |
| Posted: 11/08/2007 23:59 PM Post subject: |
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Major
Joined: 14 Dec 2006
Posts: 354
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| Wouldn't the bolt on the piston jam the ammo?
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| hubb017 |
| Posted: 11/09/2007 0:16 AM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1475
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| If you are referring to Jack's diagram, as long as everything is measured and lined up, it should work good. I'm sure his diagram was similar to mine; a rough sketch.
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| c19o |
| Posted: 11/09/2007 0:44 AM Post subject: |
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Major
Joined: 14 Dec 2006
Posts: 354
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| Alrighty then... I bet this would work great in the gun that im making. 500psi CO2 "Assault Rifle" - steel/copper - semi/fullauto
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| jackssmirkingrevenge |
| Posted: 11/09/2007 1:05 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6981
11122.02 Spud Bux
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I think it would be a better idea to combine the idea with mark's pop-off pilot concept, though perhaps it would be able idea to have a separate feeds to both chamber and pilot with a check valve from the chamber to the feed in order to ensure reliable operation.
The question is, will the piston go back far enough to reload the breech?
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