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MINI troubles

Posted: Sun Apr 08, 2012 12:15 pm
by urgle the danish cow
I have been trying to make a few mini co-axial piston valve guns and have not been succeeding very much. the problem i keep having is that the piston will seal but it wont pilot? i am using a schrader valve to fill and pilot and my pistons have all been machined nylon with rubber sealing faces. what am i doing wrong?

Posted: Sun Apr 08, 2012 12:23 pm
by streetfire
maybe the air isn't getting past the piston so there is nothing to fire make a small cut in the piston to let air through

Posted: Sun Apr 08, 2012 12:25 pm
by urgle the danish cow
streetfire wrote:maybe the air isn't getting past the piston so there is nothing to fire make a small cut in the piston to let air through
its under size, the tube inner diameter is .478 and my piston is .465

Posted: Sun Apr 08, 2012 1:54 pm
by Brian the brain
That littlebit of blowby could be huge in comparison.
How big is the barrel?
If that takes up a large portion of the sealing face and you have blowby...

well.....
there's your problem..

If you are able to machine the pistons, why not add a floating O-ring that works like a checkvalve..

Posted: Sun Apr 08, 2012 5:54 pm
by urgle the danish cow
Brian the brain wrote:That littlebit of blowby could be huge in comparison.
How big is the barrel?
If that takes up a large portion of the sealing face and you have blowby...

well.....
there's your problem..

If you are able to machine the pistons, why not add a floating O-ring that works like a checkvalve..
what do you mean? and the barrel is 6mm

Posted: Sun Apr 08, 2012 5:57 pm
by jackssmirkingrevenge