Piston Valves Explained Visually

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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MrCrowley
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Mon Jun 30, 2008 11:30 pm

Wood, deodorant can, 1 1/4" coupler, hot glue...

I cover the former two in my how-to:
http://www.instructables.com/id/Golfbal ... That-Shoo/

Because otherwise air will leak into the barrel as nothing is sealing the barrel. Because the chamber is getting sealed, air still can leak into the barrel. So by adding o-rings, the barrel is completely sealed off. Whereas in a barrel sealer, the barrel is already sealed so o-rings aren't required.
Jleon
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Mon Sep 29, 2008 7:04 pm

I've noticed that most of these pistons are 2 inches and smaller, is there a reason for that?

I was planning a barrel sealer with a 2 inch barrel and 4 inch chamber. My piston was going to be a 3 inch coupler, and that fits inside the 4 inch PVC pretty much perfectly. I haven't seen anything quite at that scale here.

So is it just really heavy? obscenely inefficient? or just ridiculously dangerous?
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Hotwired
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Mon Sep 29, 2008 8:20 pm

No, no there's no limit.

There certainly are much larger than 2" pistons around, I can think of a 90mm one off the top of my head but it's buried in the showroom somewhere. Even larger ones are about.

It just gets more expensive as you build bigger cannons.

There's the cost of building at a larger scale, the kind of recoil which can smash the plastic to bits if not dealt with plus the heavy air consumption of very large cannons to consider.

Oh yes and they're bloody noisy :P
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MrCrowley
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Mon Sep 29, 2008 8:32 pm

Jleon wrote:I've noticed that most of these pistons are 2 inches and smaller, is there a reason for that?

I was planning a barrel sealer with a 2 inch barrel and 4 inch chamber. My piston was going to be a 3 inch coupler, and that fits inside the 4 inch PVC pretty much perfectly. I haven't seen anything quite at that scale here.

So is it just really heavy? obscenely inefficient? or just ridiculously dangerous?
There are three 4" piston valved cannons I can think of, of the top of my head. So i'm sure there are more. Just use the forum search tool, and limit the results to the Pneumatic Cannon Showcase and search 4" or similar, sure you will get some dud results but shouldn't be much.
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jamie e
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Sun Jan 04, 2009 8:49 pm

AWESOME that helps so much, i've been wondering how they work for so long :D
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NetherPhoenix
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Tue Apr 21, 2009 6:51 pm

Wow, this was super helpful, really made it easy to understand how everything works out
It's times like these that i wonder, what would Carlos Hathcock do?
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Bully Dog Airsoft
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Mon Jul 20, 2009 6:54 pm

Can someone tell me how to make video semitics like this?
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Ragnarok
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Mon Jul 20, 2009 7:28 pm

Semitics? As in the study of the languages, cultures and histories of the Semitic people?
I can't even work out what word you actually meant.

Anyway, dude. This is a topic on piston valves, not making Flash animations.
But to save an argument, you'll need Adobe Flash (not Flash Player) to make this kind of thing. Prices for the new versions are into hundreds of dollars. Old versions might be found for less, but you can still expect to have to shell out a certain amount.
We will not be discussing illegal methods of getting the software.

End of discussion. I've told you what you need to know. If you need to know more, ask it somewhere appropriate. In other words, not in a thread about piston valves.
(In other words: NOT HERE {In other words: SOMEWHERE ELSE [In other words: THIS REALLY IS NOT THE PLACE]} - Got it?)

@Colty-bear: It's generally considered that with sticky threads that there's no problem with posting them, no matter the time scale involved. After all, it's always on the front page!
As you're not a moderator, it's not really your place to be rebuking people for it anyway.

Of course, that doesn't mean that Bully Dog's question was appropriate to the topic of the thread.
Does that thing kinda look like a big cat to you?
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Mateo
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Mon Jul 20, 2009 7:39 pm

i think he meant schematics? ragnarok is right this really isnt the place for a question like that... have you noticed that this forum is filled with how to make spudcannons and related items?

and ways if you really wanna know just copy and paste this into you nearest local google (dont worry google is your friend :wink: )

"how to make flash animation"

now was that very difficult?
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Ragnarok
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Mon Jul 20, 2009 7:56 pm

Mateo wrote:I think he meant schematics?
Probably. It is almost two in the morning here. I blame that.
if you really wanna know just copy and paste this into you nearest local google (dont worry google is your friend)

"how to make flash animation"

now was that very difficult?
That's not how you do it. This is how you do it: Clicky
(Feel free to use that website. Just be wary, people can get quite annoyed if when you do...)

But to be fair to him, he probably didn't know it was called Flash animation.
Does that thing kinda look like a big cat to you?
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Mateo
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Mon Jul 20, 2009 8:07 pm

That's not how you do it. This is how you do it: Clicky
(Feel free to use that website. Just be wary, people can get quite annoyed if when you do...)
wow that is the most amazing thing ive ever seen ahah.

im just irritated right now and im blaming the 105 degree wheather :cry:
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jackssmirkingrevenge
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Mon Jul 20, 2009 10:04 pm

Ragnarok wrote:But to be fair to him, he probably didn't know it was called Flash animation.
Sounds rather posh as opposed to normal, bog standard animation ;)
=Dark Wing=
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Wed Jul 22, 2009 4:57 pm

What might you use as a piston?
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MrCrowley
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Wed Jul 22, 2009 5:26 pm

=Dark Wing= wrote:What might you use as a piston?
You could use your grandma's toe if you can get hold of it :roll:

You can use ANYTHING as a piston. Every piston is different. Just go to a hardware store or look around your kitchen or garage for something that could be used as a piston. You didn't even say what size piston, so I don't see how you could expect any help.
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bazooka joe
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Tue Jul 28, 2009 5:00 pm

Ok, I've been having some issues with my first piston valve not sealing correctly. I made a coaxial with a 2 inch barrel and a 3 inch chamber, and used a longboard wheel with a couple sheets of cut rubber for the sealing face as a piston, but it doesn't seal. Whenever I put air into my launcher it all just leaks out the barrel at just a slightly slower rate then my compressor filling it. I can get it to 40 psi but its gone within 10 seconds or less.

Can anyone help me with this? I figured since this was a discussion about pistons that I could post this here. I can post pictures if needed.
Thanks in advance
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