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D*mn d*mn d*mn ...how not to test a piston valve

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: dongfang » Sat Jul 21, 2007 2:06 pm

Hi

Isn't that a 3" porting valve?

And did you buy Spudtech? Wow

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Soren
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Unread postAuthor: Gepard » Sat Jul 21, 2007 2:10 pm

Ah - you mean 75mm porting? I thought you meant 75mm T.....

Nope.

Michael
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Unread postAuthor: dongfang » Sat Jul 21, 2007 4:37 pm

Hi,

OK the one I am planning is 75 mm tee. Porting will be 63 or 75. Edit: I can't find a 90 mm tee in this perfect spudding series (but then again I didn't look very hard).

WOW just test fired the 63 mm valve at 3 bar. 4 letters: B A N G ! It threw off the barrel, and the projectile, a rag, got some of a flight.

The biggest problem now is to get it to reset reliably. Maybe a softer main seal O-ring would help after all. Right now I need to unscrew the sprinkler valve and push the piston with a rod every time.

I got some smoke bombs that fit right down the barrel. Gotta try that tomorrow.

Edit:

Oh, and Gepard, it seems to be like:

A Supah-Valve has 2" threaded porting. It is built into a 3" tee.
A Megah-Valve has 3" threaded porting. It is built into a 4" tee.

My 63 mm valve has 50 mm (2") barrel porting (for solvent welding but could have been threaded) and 63 mm chamber porting (2.5"). It is built into a 63 mm (2.5") tee.

My maybe-future 75 mm valve has either 63 mm (2.5") or 75 mm (3") barrel porting (for solvent welding but 2.5" version could be threaded) and 75 mm chamber porting (3"). It is built into a 75 mm (3") tee.

The Supah and Megah are chamber sealers. Mine is/are barrel sealers.

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Soren
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Unread postAuthor: iPaintball » Sat Jul 21, 2007 5:12 pm

What do you mean "reset"? It should clos back whaen you fill it. If you are filling from the chamber, you need a piston spring.
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Summer Projects:
CO2 tank hybrid: Gotta fix the meter :(
Cane gun: Needs a pilot/fill setup
1.5" piston valve gun: Almost done
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Unread postAuthor: dongfang » Sun Jul 22, 2007 2:33 am

Hi

Im filling from the pilot chamber. I cut some grooves in the piston to let air go from the pilot to the main chamber, after the piston has moved to the closed position ... unfortunately I cut them a little too long.

The problem is that I have an awfully slow pump, and that I fill the gun through the pilot of the sprinkler, then continuing through the sprinkler diaphragm eq hole to the pilot of the piston valve ... too much resistance, too little flow.

So I'll put a 1/4" fitting in the chamber next, and put a ball valve on it. Then at least I can get the gun to seal first, and then move the pump to the main chamber. Or I should look for the spring first. Just where do you get springs ... ?

Edit: Incredible; there are 2 spring factories in Zürich.
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Unread postAuthor: spud yeti » Sun Jul 22, 2007 11:02 am

Make a temporary chamber with the ball valve, springs are hard to use effectively.
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really good quote/phrase here
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Unread postAuthor: dongfang » Sun Jul 22, 2007 3:20 pm

Hi

You mean, another small chamber that will dump into the pilot chamber with the ball valve? Yeah could do that. Just put the ball valve between the sprinkler and the pilot chamber, and have the space there serve as chamber. Will serve as a safety latch, too.

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Soren
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Unread postAuthor: origin unknown » Thu Jul 26, 2007 4:28 pm

Beautiful valve! what did You use to grind it out with? A vertical mill? Are those sch80 fittings? Is the piston endcap sch80 too?
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Ecclesiastes 1:9 - What has been will be again, what has been done will be done again; there is nothing new under the sun.
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Unread postAuthor: zeigs spud » Thu Jul 26, 2007 4:31 pm

your idea sounds fun, take a vid of it! :D
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Unread postAuthor: dongfang » Thu Jul 26, 2007 4:57 pm

Hi,

The only grinding & machining done on that valve is:

- Burrs, cast injection remains etc. inside the tee and on the piston were removed with a big half-round file

- The piston could then just be jammed in. With careful use of dye and carbon paper I filed the tee so that the piston moves freely but not loosely

- And yes I used a vertical mill. A simple mill table from Dremel. It is actually quite good! - as opposed to their recent plastic drill stands. All I used the mill for was cutting grooves for two o-rings, and grinding away the stops in two reducers.


The parts are PN10 and PN16. I'm in Europe; I think it is the same class as Sch80. PN10 means for a nominal pressure of 10 bar, and PN16 is 16 bar. The end cap is PN16 but of course the bolt-in installation technique is not approved. Piston is PN16, as far as I remember. The curved surface should help prevent it from shattering when slamming into the bumper. Tee body is PN16. I can even get PN16 wyes, but at a price about 2.5 times that of the tees.

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Soren
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