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Pneumatic with a Coaxial valve?

Posted: Tue Feb 21, 2006 10:12 pm
by TfAv1228
Has anyone tried to make a Pneumatic cannon with a Coaxial valve?
I think that it could be done but i would have a sprinkler valve infront of it.
That way instead of just being like an automatic like a Coaxial would normally be in Pneumatic so I would be able to control it and get the power of a Coxial with a Pneumatic.


EDIT:
I have been looking at the design for the Coaxial and I cannot figure out how it works. So it just builds up pressure on each side of the plywood then you vent some pressure and it moves?

Posted: Tue Feb 21, 2006 10:24 pm
by drac
Wait, woah woah woah. What the hell did you just say?

Not to be rude or anything, but I seriously didn't comprehend any of that.

The only part I understood was "has anybody built a cannon with a coaxial valve?" and the answer is yes.

From there on I could understand none of it.

Maybe I'm having a bad week or somthing, maybe I forgot to take my pills.

Posted: Tue Feb 21, 2006 10:25 pm
by boilingleadbath
Look up "diaphram valve" or "piston valve" in the spudwiki. That should answear your questions as to the opperation of the valve.

And yes, coaxial valved pneumatics are acctualy pretty common - and not as hard to make as they may sound, or at least I havn't ever had any problems with them (my first cannon was a co-axial pneumatic).

What do you mean by "...have a sprinkler valve infront of it."? Use the sprinkler valve as a pilot valve? Again, that's fairly common too.

Posted: Tue Feb 21, 2006 10:31 pm
by Atlantis
My question is, "WHAT THE HELL WOULD THE PLYWOOD BE FOR!?!" and what do you mean by automatic? Is anyone else sick of noobs posting topics to ask questions about the most basic of spudgunning concepts? DO SOME BEEPING RESEARCH!

Posted: Tue Feb 21, 2006 10:35 pm
by TfAv1228
Ok well seeing as in the picture in the how to section has PLYWOOD in it and it does not appear to be user controlled seing as their are no real labels on the diagram(and if its not user controlled it would just fire each time it builds up enough pressure and would be automatic). OK really you are oging to call someone a noob who has been looking into it and was confused with 1 thing so instead of wasting time and money then whining here afterwards saying "help i f*cked my cannon" I ask a question.

EDIT:
I see where the user vents some pressure. Thank you boilingleadbath for not being a d*ck and pointing to a position where i could learn more.

Another question. How would a coaxial valve be reset would you jsut shake it until its up against the barrel again or is there a spring than pushes it back agianst the barrel?

Posted: Tue Feb 21, 2006 11:21 pm
by Atlantis
The air that comes in from your pump presses the piston back to the barrel. All a spring does is absorb some of the force of the moving piston. Sorry for yelling at you, but I've seen too many people ask dumb questions. I see what you meant by plywood now. It's not a good idea to use plywood in your piston, the force of the piston slamming around might splinter the wood into tiny pieces. Use steel washers instead, or even and endcap of the appropriate size.

Posted: Tue Feb 21, 2006 11:38 pm
by TfAv1228
Would anyone say that homemade Coaxials are more efficient than Modded Sprinkler valves? They work the same way.

Posted: Wed Feb 22, 2006 12:03 am
by Shrimphead
Yes I would. The opening that they create is much bigger than a sprinkler valve. That's why people take the time to make their own pistons. If sprinkler valves were more efficient, then it would be easier and better just to go with those. Because they aren't, people who want really good performance make coaxials and other piston valve designs.

Posted: Wed Feb 22, 2006 6:50 am
by drac
Ys, they would be more efficient. A normal sprinkler orifice is what, .967 inches? (BLB to the rescue)
If you build a piston valve that has a 1 inch barrel, you already have more flow than a normal sprinkler.

Posted: Wed Feb 22, 2006 4:22 pm
by boilingleadbath
The (optional) spring is used to reset the valve; it pushes the diaphram/piston back into place. (this has scence been added to the wiki)
A spring (as implyed by "optional") is not needed, and I would venture to geuss that most people don't reseat their valve with one, but instead simply fill the chamber from behind the diaphram - which understandably causes the piston/diaphram to move forwards and seal against the barrel.

And I do believe that the wiki states the relitive preformance of piston/diaphram valves and sprinklers. (but if not, I'v added it)