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Is this ok?

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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Is this ok?

Unread postAuthor: elitesniper » Sun Dec 30, 2007 7:35 pm

Hey guys , i just posted this topic to ask you guys if im doing my piston right so here are pics .
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piston side.JPG
side of the piston its made out of a medicin bottle so its hollow inside is that ok?
piston tee 1.JPG
the tee and the piston inside
pisyon.JPG
the mouse pad sealing face.
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Unread postAuthor: ALIHISGREAT » Sun Dec 30, 2007 7:44 pm

well the hollow piston could be a problem, how thick are the walls... if you are not cofident they are thick enough to holdback the pressure you will use you should fill it with epoxy or something.
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Unread postAuthor: jrrdw » Sun Dec 30, 2007 7:47 pm

There is only one way to find out if any piston is going to work. Try it. It looks good so far.
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 7:47 pm

well there thick enough that i cant bend it with my fingers. :) and one more thing home depot sells 1/4 female threaded tees right?
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Unread postAuthor: mark.f » Sun Dec 30, 2007 7:50 pm

Drill holes into the hollow piston to prevent collapsing from compressed air on the outside.

Also, you may have problems with the sealing face. If the rubber foam is open-cell construction, air will leak through it.
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Unread postAuthor: Hotwired » Sun Dec 30, 2007 7:53 pm

Nothing wrong with a hollow piston, the lighter the better as long as it can take the pressure you're using and only one way to find out with a medicine bottle :)
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 8:19 pm

well its the pepto bismol one :D seems prety sturdy so ill just try it. it should take the pressure if not ill just fill it with expanding foam or somthing, can i make it serviceable by using a threaded end cap in the back of the piston?
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Unread postAuthor: mark.f » Sun Dec 30, 2007 8:53 pm

Just make sure it's a pressure rated plug, not a cleanout cap.

Or, you could use screws and a gasket, like this:

<div align="center">Image

The gasket is between the green 2" SCH-40 and the bushing.
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 9:19 pm

thanks but my piston isnt that short im guna put a threaded coupler thingy behind with a threded plug so i just unscreaw it to service it. :DWAIT and a blow gun will be enough to pilot the piston? since its very light.
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Unread postAuthor: MrCrowley » Sun Dec 30, 2007 9:23 pm

elitesniper wrote:thanks but my piston isnt that short im guna put a threaded coupler thingy behind with a threded plug so i just unscreaw it to service it. :DWAIT and a blow gun will be enough to pilot the piston? since its very light.


<A HREF="http://www.spudfiles.com/forums/the-true-power-of-a-piston-valve-t11276.html">Don't forget the bumper, or else.</a>

A blow gun should, if your piston is made well. Though I would recommend a 1/4" or 3/8" ball valve for best performance.
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 9:27 pm

ouch thats gotta hurt MrCrowley :shock: , but yea you can see the bumper behind the piston its epoxyed on there tight, its those cushiony things from drum symbols
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Unread postAuthor: MrCrowley » Sun Dec 30, 2007 9:32 pm

Yeah that's where I got mine from too :P

Just make sure the piston isn't small enough to get jammed in the threaded adapter like mine did :roll:

On a side note, the SGA is back up and running with a sprinkler valve for pilot.
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 9:35 pm

haha congrats MrCrowley :lol: i thought she wouldnt make it :( . haha
and how much of a differnce did the sprinkler make?
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Unread postAuthor: MrCrowley » Sun Dec 30, 2007 9:41 pm

A LOT! Well in sound anyway, it's incredible at just 50psi, i've had people hear it as far away as the beach, which is over 300m away.
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Unread postAuthor: elitesniper » Sun Dec 30, 2007 9:45 pm

wow thats louder then my burst disk :D
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