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pilot valve?? shrader?

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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pilot valve?? shrader?

Unread postAuthor: FORE!!!! » Tue Aug 18, 2009 12:54 am

ive recently completed making a mini chamber sealing piston valve,using chrome mini cistern cock,3/4 copper for the chamber and 1/2 copper for the pilot volume which is actuated by a shrader

problem being that when i press the shrader the air just flows out of the end and not on the berrel side

what could the problem be???

is the chamber too small? ,does it need higher pressure to actuate??
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Attachments
Photo 148.jpg
mini cistern cock
Photo 149.jpg
just a basic prototype to see if things work
Photo 150.jpg
pilot volume ,shrader and piston in the back housing
Photo 151.jpg
the piston
Photo 152.jpg
the piston chamber housing
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Unread postAuthor: MrCrowley » Tue Aug 18, 2009 12:56 am

Need a bigger pilot valve, try a 1/4" ball valve or blowgun.

Edit: Assuming your piston is a good fit inside the piston housing.
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 18, 2009 1:18 am

When the air just escapes through the pilot valve, the problem is almost always that the piston is not tight enough, ie you have bigger flow around the piston than through the pilot.

Also, pilot volume is a tad excessive...
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Unread postAuthor: MrCrowley » Tue Aug 18, 2009 1:20 am

Unless you o-ring that piston air tight and connect the schrader directly to the back of the tee/piston housing, a schrader valve will give you poor performance as a pilot valve. Even if you did do the above, a blowgun will give you far better performance.
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Unread postAuthor: FORE!!!! » Tue Aug 18, 2009 1:34 am

thanks for the responses i think ill go with a blow gun and see how it goes..

another question tottaly unrelated, how do i make a signature if ive already brought signature privliges???
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Unread postAuthor: MrCrowley » Tue Aug 18, 2009 1:37 am

FORE!!!! wrote:thanks for the responses i think ill go with a blow gun and see how it goes..

another question tottaly unrelated, how do i make a signature if ive already brought signature privliges???

I'd recommend making sure your piston is a nice fit too, that'll improve performance.

Scroll down here:
http://www.spudfiles.com/forums/profile ... ofile.html
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Unread postAuthor: Willdebeers » Tue Aug 18, 2009 3:34 am

I agree with MrC, This is the mistake I made with all of my first piston guns. Try to reduce the pilot volume, use a better (bigger?) pilot and Make sure the piston is quite near to airtight.

WilldeBeers
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Unread postAuthor: FORE!!!! » Tue Aug 18, 2009 6:25 am

well i tryed using a blowgun to no avail, would an excessive pilot volume stop the piston from hitting regardless of performance issues???

if not i guess my piston may have a sealing problem,altho it does fit near perfect to the housing considering its the brass shart from the valve it self?
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al-xg wrote:
I've used various things like cutting oil, silicone lubricant, even butter

jsr wrote:
This collection of containers on your bedside table must look very intimidating to any visiting young ladies

...but hey, lube shows you care;)
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Unread postAuthor: jmadden91 » Tue Aug 18, 2009 6:36 am

Mine wouldnt actuate with the schrader or the blow gun and it is (as stated above) because of the piston not being a perfect fit. As I liked my Piston, i simply added a 1/4" QEV as the pilot, then the blow gun to pilot that.

Your an Aussie too right? If so check out bellpro, they have 40% off at the moment and cheap shipping.

http://www.bellpro.net/xcart_program/home.php?cat=268

A 1/4" one comes down to $21.53. Pretty good
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Unread postAuthor: FORE!!!! » Tue Aug 18, 2009 7:04 am

yeah dude im aussie,but i hate ordering crap of the internet,it kills me with anticipation,,not to worry tho cause i finally got it to work

it took exaclty one turn of teflon tape to to get it right and even then its a tight fit,hooray the first (to my knowledge)mini cistern cock chamber sealing piston gun
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al-xg wrote:
I've used various things like cutting oil, silicone lubricant, even butter

jsr wrote:
This collection of containers on your bedside table must look very intimidating to any visiting young ladies

...but hey, lube shows you care;)
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Unread postAuthor: jmadden91 » Tue Aug 18, 2009 7:10 am

Nice one mate, congratulations. Oh and bellpro offers next day delivery hahah I sound like their bloody salesman haha
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Unread postAuthor: FORE!!!! » Tue Aug 18, 2009 7:21 am

next day delivery thats nice to know,and those are very sexy qev's
maybe for my next project,,,well if u were there sales man u definatly had me :wink:
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al-xg wrote:
I've used various things like cutting oil, silicone lubricant, even butter

jsr wrote:
This collection of containers on your bedside table must look very intimidating to any visiting young ladies

...but hey, lube shows you care;)
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FORE!!!!
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