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My new valve 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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My new valve design

Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 12:28 am

Hi Guys, I thought up this design a couple of weeks ago and i started to think of how to make it better, it's for an assignment at the end of the year and i thought i might get a heads up before it starts. I came up with this final design and I would like to know what everyone thinks about it. I like any feed back and would appreciate it if anyone suggests some improvements.

Sorry about the lack of labels and details but I think everyone can work out that it's metal and the black strips on the animation is neoprene sheets, the valve construction is going to be done in my school's workshop and it's going to be made out of aluminum or low carbon steel or medium carbon steel. The dimensions are 100mm diameter, about 30mm long and it will be machined from a piece of 100mm rod. It will be fitted into the chamber and bolted in between the two sheets of neoprene at the pressurized end. It will be automatic or semi-automatic, toggled by a rod going into the smaller piston's cylinder that stops the piston going up, which isn't in the animation. I think I left out some info there so feel free to ask any questions about it and I'll answer them when i get around to it. :twisted: :twisted: :twisted:
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Valve 2.swf [ 54.03 KiB | Viewed 569 times ]

Last edited by .:: :TomDom: ::. on Sat Mar 24, 2007 12:45 am, edited 1 time in total.
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Unread postAuthor: A-98 » Sat Mar 24, 2007 12:38 am

so is it like 2 tiny pistons in one big piston?
im not sure how you would connect that to the gun...
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 12:41 am

It goes inside the chamber and is bolted like it says, i don't know how to build a piston valve at all I just thought of this and how i could use it as a good air dumper. thanks for the question. if you look at the whole thing you can see that it's already inside a chamber type thing.
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Unread postAuthor: Flying_Salt » Sat Mar 24, 2007 12:59 am

The air would start leaking out long before the second pistol could move, once there is a hole, it will leak out. Burst disks might help with that?
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Unread postAuthor: A-98 » Sat Mar 24, 2007 1:03 am

which hole are you talking about? i dont think the one that the rod goes thru would leak, cause its isolated.

the only problem that i see is that the rod will jam agains the seconday piston, causeinf emense friction, could be solved with a ball bearing roller thing.

as for the piston actually functioning ...i dont know.....
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 1:04 am

That's what the springs are for, and the bit of metal attached to the small piston that stops the big piston moving, the springs are just there to say "the piston will go back to the starting position" because if the springs don't work then i'll have to find something else to send the pistons back, thanks for the question and yes, i think that bust disks would work, but that defeats the purpose of the valve, i want a valve that wont break often and doesn't need anything extra that requires me to stop shooting :twisted: :twisted:
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 1:07 am

i think he means the one that actually gives the air to the barrel
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 1:11 am

yeah the friction is a problem for me too, it has me stumped on what i'm going to do about it, but i don't know if it will matter or not because a havent even made it yet
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Unread postAuthor: A-98 » Sat Mar 24, 2007 1:21 am

i would use something along the lines of a ball point pen setup. have a ball bearing in a cup on the end of the rod. this would allow it to roll by and have significantly less friction.
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 1:26 am

thats exactly what i was thinking about a couple of days ago, im still thinking about it and i think it will solve the problem, but it brings up a new one too, how the hell would i make a thing like that, all i have in the workshop is a mill, drill press , a lathe and like every hand tool imaginable
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Unread postAuthor: A-98 » Sat Mar 24, 2007 1:49 am

i make potato cannons and all i have is a dremel :lol:

take the mill and make a cup thing attached to the rod, a cup with a hole in it. and weld them together around a lubricated ball.

like so:
Image

however, you have to be damn good to make that sort of thing.
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Unread postAuthor: .:: :TomDom: ::. » Sat Mar 24, 2007 2:29 am

yer aye, now remember that rod is very thin, about 12mm, and its not a good idea to weld metal that's that small but im sure ill find a way
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Unread postAuthor: chaos » Sat Mar 24, 2007 2:46 am

you can weld 12mm ive welded 3mm before and its easy and theres nothing wrong with it either....its when your welding 1.2mm- .8mm is when it gets tricky.

peace
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Unread postAuthor: jrrdw » Sat Mar 24, 2007 6:03 am

The spring behind the main piston looks like it will have to be the entire lenth of your set up, or the main piston wont seal back up after accuation. As for the bearing, it should be a pinned roller inside the drilled out end of the guide rod. Easier to make, way more relieable. Stop double posting, there is a edit butten, just edit you post if you forget to include something.
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Unread postAuthor: Hotwired » Sat Mar 24, 2007 6:38 am

It'll jam or break if made to that design unless you've got some exotic materials handy.

Image

That rod has been edited to touch that sliding thing (which it will) and the red area is where it buggers everything up.

The force on the tip of that contacting rod will be the same as the force on the WHOLE SURFACE of the dump piston
(think stiletto heel) and if you do manage to get the sliding thing stiff enough to withstand that you're going to have
a lot of friction going on, enough to jam the sliding thing.

Having said that its good to see new ideas being floated on valve types :)
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