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my first piston valve (picture and video)

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: Technician1002 » Mon May 11, 2009 11:21 pm

Mitchza89 wrote:I now use hand machined aluminum. It's very easy to machine on a wood lathe, it just takes a little more time.


Have you considered using material with a lower specific gravity? The same force on 1/2 the mass = twice the speed.

Aluminum = 2.55 - 2.8

Polyethylene = 0.97

Nylon 6 Cast = 1.16

Brass = 8.4 - 8.7
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Unread postAuthor: Gippeto » Tue May 12, 2009 12:34 am

far_cry wrote: can this piston valve handle 1000 psi ?


After a little research and some calculations, it would seem that the cast brass tee should withstand 1000psi with a decent margin of safety.

That being said, if it were me, I would replace the brass tee with a steel one...just to be sure.
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Unread postAuthor: Tony.Knaak » Tue May 12, 2009 1:24 am

Please take Gippeto's advice and remove the teflon tape when you go into final assembly, I don't believe it is that reliable.

I would recommend using the Loctite Black Max since it rated by Loctite as their strongest. Here is a link to a pdf brochure about Loctite products so you can compare adhesives if you wish.

http://www.instantsolutions.loctite.com/LT_4435.pdf

I have a small bottle of Black Max that I got from work, but I have not tested it in the pressure range you are suggesting.
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Unread postAuthor: far_cry » Tue May 12, 2009 11:51 am

Tony.Knaak wrote:Please take Gippeto's advice and remove the teflon tape when you go into final assembly, I don't believe it is that reliable.

I would recommend using the Loctite Black Max since it rated by Loctite as their strongest. Here is a link to a pdf brochure about Loctite products so you can compare adhesives if you wish.

http://www.instantsolutions.loctite.com/LT_4435.pdf

I have a small bottle of Black Max that I got from work, but I have not tested it in the pressure range you are suggesting.


thank you gippeto,i will change the T with steel one

and tony thank you to ,
and i found that the Teflon not just make the valve leak, also the water line i install in the home leaking to , so i return to the old fashion method
:D :D :D :D :D :D :D i don't know if you guys know this stuff

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Unread postAuthor: neeewwww » Sun Jul 19, 2009 3:49 pm

@far_cry: Can you tell me the inner diam. of you barrel port?

I have found where is my error, as stated by BTB:

I think there is no-or not enough difference in diameter between the sealing face surface and the crosssection of the piston itself.

IOW, the pressure has no surface to push against..


The barrel port, is the same diam of the max diam. of the piston... So theres not enought surface to push...

http://www.spudfiles.com/forums/piston- ... 18757.html
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Unread postAuthor: far_cry » Sun Jul 19, 2009 5:46 pm

in my case is 12 mm

the seat diameter must be smaller than the piston at least 2mm (from the all sides) .bigger is better but not to much ,or you will got small seat thats kill the flow
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Unread postAuthor: neeewwww » Mon Jul 20, 2009 11:58 am

@far_cry: Do you think that a ~7mm, constricts much flow? Running at aprox. 100psi, using a 1/2" pipe and a 3/4" as barrel... Fire extinguisher as chamber (1.125liters), and piloted by a 1/2" BV.


o>
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Unread postAuthor: far_cry » Mon Jul 20, 2009 12:49 pm

will i am not that good in the flow thing
but i think is small. try it and change the seat diameter to 12mm~ and if this get more power
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