Will this piston valve work?

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Gunner
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Sun Oct 21, 2007 10:15 am

Here is the picture,any suggestions?
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potatoflinger
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Sun Oct 21, 2007 10:37 am

Yeah, it should work, but you should check the wiki before you make a post like this. The type of piston you are thinking of is a piston in a tee, and ti has been done many times before. I'm not trying to flame you, but it is a common mistake that new members make (I did it a few times)
It's hard to soar with eagles when you're working with turkeys.
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Sun Oct 21, 2007 11:03 am

OK,but what does it matter when piston is in tee? :wink:
SpudBlaster15
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Sun Oct 21, 2007 11:57 am

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Bluetooth
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Sun Oct 21, 2007 12:52 pm

It will work, but your piston is going to have to be very short because the bushing that you would put in the end to plug it up will take up most of the space. SpudBlaster15, you do not need to cut out anything, or slide a pipe in. It would let the piston slide back further, but is not needed.
Gunner
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Sun Oct 21, 2007 1:05 pm

OK,how about now,better? :)
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spanerman
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Sun Oct 21, 2007 1:08 pm

yup



message to short
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SpudBlaster15
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MrCrowley
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Sun Oct 21, 2007 4:39 pm

Damn I wish we had some sort of built in paint program when posting.

Anyway, what most people do is sleeve the tee with the same diameter pipe as the tee itself. You only need about 2" of this pipe but you should measure it beforehand.

Now what you need is a reducing threaded plug, this means it goes inside the tee, but reducers down to say 1/2" threads, where you can attach your pilot setup.

Find out how much room the plug takes up in the tee, and find how long the tee's socket is(from the opening of the tee socket(where the pilot setup will be) to the 'lip' which is just before the opening socket to the bottom of the tee) This will only be about 5" long.

So say your plug is 3" long, that means you need some pipe to sleeve the tee which is only 2" long. Cut the pipe, jam it in the tee, and makea piston for it.

Try and have the seat(barrel) a bit further forward then you have it now, and then you need to make a piston which fits inside the sleeved tee, is lnog enough to seal against the seat(barrel) without the piston coming to far forwards(you will have piloting problems if this happens) and so the piston has enough room to be pushed back when the piston fires.

Here's a quick diagram:

Black = Tee
Green = sleeved pipe
Maroon = 'lip' inside tee
Grey = Reducing threaded plug
Brown - Pilot setup
Yellow = fill valve
red circle = ball valve(pilot valve)
Orange = piston(the grey is a bolt and the washer holding on the sealing face)
Purple = Barrel
Sky Blue = sealing face

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Gunner
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Mon Oct 22, 2007 1:01 am

OK,thanks for the picture and suggestions. :wink:
Tsukiten
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Mon Oct 22, 2007 2:10 pm

Hey hey hey hey guys
This can't be right...doesn't all the compressed air need a surface to push the piston back against? Or does it work on a different way...?


Edit: Oh sorry I think you guys meant that the air can flow to the front of the piston to push it back, my bad...
If you experience glitches and/or distortions in the space-time in close proximity to yourself, the above post may be an alteration of the truth.
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watto
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Tue Oct 23, 2007 4:33 am

As of today I have my own working piston cannon so I'm officially allowed to advise people lol, I found the main things are to make sure the end of the barrel that contacts the piston is perfectly level and smooth, I used some really fine wet and dry sandpaper then buffed it. Also don't leave much space behind the piston you only need a bit more than 1/4 of the barrels diameter. Make sure you get a big pilot valve not just a blow gun. Don't drill an equalization hole in the piston the air will get around the outside no matter how perfect the fit is. Make sure you can remove the piston so you can fix it if you need to. And most of all give the pipe glue 48 hours to dry not 24. I have to buy and glue a new plug because I didn't leave the glue long enough before testing it.

Good luck
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chaos
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Tue Oct 23, 2007 4:51 am

In the interests of correct information for searching users;

Make sure you get a big pilot valve not just a blow gun.
not so true

Don't drill an equalization hole
not so true


all the rest is good tho mate, knowledge is power!!
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watto
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Tue Oct 23, 2007 6:39 am

chaos wrote:
Make sure you get a big pilot valve not just a blow gun.
not so true
Well generally the bigger the pilot the better the gun will work within reason.
chaos wrote:
Don't drill an equalization hole
not so true
Unless your machining a piston with o-rings, which this guy isn't, your not going to need an equalization hole...
Gunner
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Tue Oct 23, 2007 7:28 am

What is the right size tee because I am gonna use barrel which ID is 20mm and outer diameter something 22mm?Something 30-40mm?
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