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2inch piston valve problems

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2inch piston valve problems

Unread postAuthor: superspud09 » Fri Sep 24, 2010 3:46 pm

Hi im new to this forum but not to spud guns. i encountered a problem with my barrel sealing piston valve and i cant seem to figure it out... its a 2 inch t and a 1 1/4 coupler filled with hot glue for the piston. when i fill the air chamber the valve seals air perfectly but when i hit the pilot the valve does not open what is wrong here? help would be greatly appreciated :D
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Re: 2inch piston valve problems

Unread postAuthor: Matt_NZ » Fri Sep 24, 2010 4:07 pm

superspud09 wrote:when i hit the pilot the valve does not open what is wrong here? help would be greatly appreciated :D


Hey,

What pilot valve are you using and what is the volume of the pilot?
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Unread postAuthor: superspud09 » Fri Sep 24, 2010 4:15 pm

Im just disconnecting my air line for the pilot for now..volume is about 4.7 cubic inches
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Unread postAuthor: Lockednloaded » Fri Sep 24, 2010 4:19 pm

You need a much better pilot, or much less pilot volume
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Unread postAuthor: superspud09 » Fri Sep 24, 2010 4:28 pm

Lockednloaded wrote:You need a much better pilot, or much less pilot volume

would a 1/2 inch ball valve do the trick?
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Unread postAuthor: Fnord » Fri Sep 24, 2010 4:33 pm

The less difference there is between the port diameter and the piston diameter, the faster your pilot needs to be.
This is because there isn't much force acting on the small exposed surface area. You can avoid this by making a better seal between the pilot volume and chamber(o-rings), or using a bigger pilot valve.

I would hope a 1/2" BV would do it, but if it doesn't try adding an o-ring.
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Unread postAuthor: Gun Freak » Fri Sep 24, 2010 4:41 pm

A 1/2" ball valve should suffice or upgrade to a larger valve like a sprinkler valve or a smaller piston valve. Also, why did you full the piston with hot glue? It only makes it heavier and moves slower, and you could have just used plugs to make it lighter.
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Unread postAuthor: superspud09 » Fri Sep 24, 2010 4:41 pm

Fnord wrote:You can avoid this by making a better seal between the pilot volume and chamber(o-rings), or using a bigger pilot valve.


Will air be able to get past the o-rings to fill the chamber?
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Unread postAuthor: Gun Freak » Fri Sep 24, 2010 4:45 pm

Well you can use a floating o-ring or it will be like my piston in which the o-rings only make a tigher fitting piston while still letting air get by.
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Unread postAuthor: Fnord » Fri Sep 24, 2010 4:46 pm

Yes, if you put a tiny hole in the piston to bypass it, or if you make a floating oring design. Chances are you won't need to do either since I doubt your first attempt at using orings will seal perfectly. It took me at least 2.546 *10<sup>15</sup> attempts to get it right without a lathe.
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Unread postAuthor: superspud09 » Fri Sep 24, 2010 6:39 pm

Thanks for the help guys im going to put orings in and try the ball valve for now
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Unread postAuthor: SpudBlaster15 » Fri Sep 24, 2010 10:55 pm

Gun Freak wrote:or it will be like my piston in which the o-rings only make a tigher fitting piston while still letting air get by.


:lol: Gotta love that kind of engineering...

Fnord wrote:Chances are you won't need to do either since I doubt your first attempt at using orings will seal perfectly. It took me at least 2.546 *1015 attempts to get it right without a lathe.


With careful design, they should seal perfectly on the first try. Calculate, measure, calculate, measure, measure... In that order. It's perfectly doable with hand tools if you have the skills and patience.
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Unread postAuthor: clemsonguy1125 » Sat Sep 25, 2010 9:07 am

If you have issues with the O-rings, glue craft felt around the piston, it compresses as you slide the piston in. Medical Tape also works well.
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