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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: SEAKING9006 » Wed Mar 18, 2009 12:26 pm

One; Do not bump old topics with just a question to the builder.
Two; It won't because the pressure is pushing the other way. It wants to go LEFT.
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Unread postAuthor: clide » Sat Mar 21, 2009 10:22 pm

To clarify what Seaking said. The pressure is pushing it to the left because the left side of the piston is slightly larger than the right.

There is also a physical stop (The threaded adapter by the middle piston) that stops momentum from carrying the piston too far forward.
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<a href="http://gbcannon.com" target="_blank"><img src="http://gbcannon.com/pics/misc/pixel.png" border="0"></a>latest update - debut of the cardapult

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Unread postAuthor: mattyzip77 » Wed Aug 29, 2012 8:46 am

I know this is a old thread but is clide still around?? This gun and valve is freakin unreal!!!!!! :shock: :shock: :shock:
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Unread postAuthor: POLAND_SPUD » Wed Aug 29, 2012 9:25 am

nothing you couldn't achieve with a 3 way + QEV + air cylinder combo

the biggest problem is that you need lots of compressed air - if your chamber is for example 1 litre @ 10 bar you need 10 litres of air at atmosferic pressure

now if you want just 3 RPS rate of fire then you need 30 litres of air... to make matters worse your gun and all of its parts have to be able to deliver that 30 litres of air in one second... so forget about using small and cheap DCVs as they might constrict the flow too much
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Unread postAuthor: jackssmirkingrevenge » Wed Aug 29, 2012 9:36 am

POLAND, this is why regulated HPA tanks exist ;)
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Unread postAuthor: POLAND_SPUD » Wed Aug 29, 2012 11:08 am

I am not sure what you're saying... I mentioned litres of air at atmospheric pressure just to show how much flow each part has to handle

I doubt the reg on your setup could provide enough flow for a largebore fullauto gun operating at let say 5 RPS
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Unread postAuthor: jackssmirkingrevenge » Wed Aug 29, 2012 4:09 pm

There are high flow regulators... or you could drive yourself crazy by using a pop-off to refill the chamber and trying to balance the firing cycle :)
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Unread postAuthor: velocity3x » Wed Aug 29, 2012 5:11 pm

I use one these .... It provides more than enough volume for 60 rpm's at 60 bar. It has a max pressure of about 408 bar.

http://www.scottgrossstore.com/servlet/the-61010/Harris-Model-8700-dsh-6000-dsh-677-High/Detail
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Unread postAuthor: POLAND_SPUD » Wed Aug 29, 2012 6:13 pm

sure but that's 60 rpm per 60 seconds in a minute right?? now try to get 5 RPS and you're fcked

not to mention that your gun isn't really self contained or something you can carry on your back
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Unread postAuthor: velocity3x » Wed Aug 29, 2012 7:12 pm

POLAND_SPUD wrote:sure but that's 60 rpm per 60 seconds in a minute right?? now try to get 5 RPS and you're fcked



My bad....I read that as 5 rpm rather than 5rps.
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Unread postAuthor: jackssmirkingrevenge » Thu Aug 30, 2012 12:09 am

I think velocity3x can confirm that if you're making an HPA auto with a relatively big bore, 1rps is more than enough to devastate pretty much anything...
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Unread postAuthor: POLAND_SPUD » Thu Aug 30, 2012 4:00 am

maybe it is but he knew that flow will be a problem and he took special care and ordered parts that offer good flow just to get it to work at 1 RPS

so the point is -> fullauto guns require a lot of flow and that has to be taken into consideration when designing a gun
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Unread postAuthor: ramses » Thu Aug 30, 2012 9:47 am

POLAND_SPUD wrote:so the point is -> fullauto guns require a lot of flow and that has to be taken into consideration when designing a gun


And auto hybrids get 760% more flow per flow!
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Unread postAuthor: al-xg » Thu Aug 30, 2012 10:36 am

so the point is -> fullauto guns require a lot of flow and that has to be taken into consideration when designing a gun


Yep, one of the biggest issues I encountered when trying to get my 14mm full auto prototypes to function at a decent power level and rate of fire.
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