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piston not opening, help me please

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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piston not opening, help me please

Unread postAuthor: covey12 » Mon May 11, 2009 1:09 pm

my piston valve will not open when i pilot it it, all of the air comes out of the pilot, which is a 1/4 inch ball valve, on a 2" piston, when i push a stick down the barrel and push the piston back manually, the air does come out
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 1:31 pm

What's the diameter of the barrel? How tight is the piston?
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Unread postAuthor: covey12 » Mon May 11, 2009 1:38 pm

jackssmirkingrevenge wrote:What's the diameter of the barrel? How tight is the piston?


barrel is 1.5inch, and the piston is a 1.5in. endcap so it has about 1mm of clearance between it and the housing,
i do have a spring pushing the piston onto the barrel, it only has about 2lbs of force though
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 1:48 pm

You don't have a lot of difference between the external diameter of the barrel and the diameter of the piston, this can be an issue.

Try wrapping duct tape around the endcap until it's tight but you can still push it with one finger, see if it works.
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Unread postAuthor: Ragnarok » Mon May 11, 2009 1:52 pm

jackssmirkingrevenge wrote:You don't have a lot of difference between the external diameter of the barrel and the diameter of the piston, this can be an issue.

No, let's be fair - this is almost certainly the issue.

Like Jack says, you'll need to cut blowby on the piston - or seriously upgrade your pilot valve.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: covey12 » Mon May 11, 2009 1:53 pm

jackssmirkingrevenge wrote:You don't have a lot of difference between the external diameter of the barrel and the diameter of the piston, this can be an issue.

Try wrapping duct tape around the endcap until it's tight but you can still push it with one finger, see if it works.


any tighter and it wont move, i think that is my problem, 1mm is probably not right, it may be a 1.75 inch endcap
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 1:58 pm

Try getting rid of the spring then ;) you don't really need it assuming you're filling through the pilot chamber.
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Unread postAuthor: CpTn_lAw » Mon May 11, 2009 2:21 pm

Get rid of the Spring. grease the endcap.
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Unread postAuthor: Ragnarok » Mon May 11, 2009 3:10 pm

@CpTn_lAw: That's what she said.

Sorry, couldn't resist.
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 3:33 pm

Ragnarok wrote:That's what she said.


I could conceive of a situation where one would be told "Smear some KY and stop bouncing!", but I think this is veering somewhat off topic :roll:
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Unread postAuthor: POLAND_SPUD » Mon May 11, 2009 3:42 pm

:shock:
boys will be boys.... lol
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Unread postAuthor: covey12 » Mon May 11, 2009 3:45 pm

Ragnarok wrote:@CpTn_lAw: That's what she said.

Sorry, couldn't resist.


that helps me, come on now were not in middle school anymore
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 3:55 pm

covey12 wrote:come on now were not in middle school anymore


Considering some of us are grown men discussing the acceleration of vegetables, I think that assertion is open to debate ;)
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Unread postAuthor: Ragnarok » Mon May 11, 2009 6:11 pm

@ covey12: The true mark of maturity is to be able to controllably allow oneself to be immature at times.

Anyway, you're not helping us help you... you're expecting us to troubleshoot on inconsistent or lacking information - and pictures are ALWAYS a help in problem diagnosis.
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Unread postAuthor: far_cry » Mon May 11, 2009 6:50 pm

make the seat diameter smaller
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