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Jack's semi pellet gun?

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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Unread postAuthor: jackssmirkingrevenge » Tue Apr 10, 2007 12:03 pm

Hawkeye wrote:You might as well grease it up well, add the o rings and cast right over them don't you think?


That's practically what I did, though instead of o-rings I cut holes in sections of neoprene to make my own seals. What I meant was the bolt itself should have grooves with the o-rings mounted on it, in the manner of a piston in a chamber sealing valve.
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Unread postAuthor: Solo » Tue Apr 10, 2007 6:09 pm

So do you think the o-rings on the outside like that would suffer from the same friction levels as your neoprene disks? For that matter, would having the orings on the bolt even be that much better?
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 11, 2007 11:38 pm

I'm not sure, I've seen some pretty friction-free setups using o-rings so conceivably it could work. Another solution which I considered was to have a friend machine the bolt and housing for me to extremely fine tolerances, of course this would leak a little but you could add a separate ball valve beween the chamber and the breech to ensure that it only leaked while firing so air loss would be negligible.
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Unread postAuthor: Antonio » Thu Jan 31, 2008 7:50 am

Hey I just noticed this valve is just like the one used in the drozd airgun. If this valve works we have the ultimate valve. Yeah I guess machining is the only option. The friction of the o-rings is such a fuss.
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Unread postAuthor: Hawkeye » Thu Jan 31, 2008 9:05 am

Is this not identical to the Drozd system that Ant posted the animation to? A bit more stretched out but functionally identical.
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Unread postAuthor: Antonio » Thu Jan 31, 2008 9:22 am

Hawkeye wrote:Is this not identical to the Drozd system that Ant posted the animation to? A bit more stretched out but functionally identical.


Well I meant the valve that I made according to the drozd's working:
Image
Image
Image
The problem was that the orings created too much friction.
Check this link: homemade valves

Edit: I just noticed that this post is pretty old.
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Unread postAuthor: jackssmirkingrevenge » Fri Feb 01, 2008 3:45 am

I had made this several years ago - spudtech post June 2004! - unfortunately it's hard to compromise between a good seal and limiting the friction, though I suppose it you were willing to live with a slight leak you could make it just a right fit and remove the o-rings.
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