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Pitbull 9, semi auto 9mm!,New pics/upgrades page 3

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: jackssmirkingrevenge » Tue Aug 18, 2009 4:06 pm

POLAND_SPUD wrote:well it's difficult to get the idea of power if all you've got is a bunch of numbers from GGDT...
something like 30J or 150m/s doesn't really tell you much


It does if you have some idea of airguns and firearms, it's true that once you're dealing with high energy figures because of projectiles much larger than bullets at relatively slow speed it doesn't really make for a useful comparison but for smaller calibre launchers you get a pretty good idea. For example, a 15J air rifle is good enough for rabbit hunting at 50 yards if you can hit the thing. Not advocating hunting for spudguns, just giving an example of power.

you know, price wouldn't be a problem on a gun that fires one round per minute but as ROF increases this starts to be a major problem


Very true, personally ammunition cost and availability is a major factor when it comes to deciding the calibre of an auto project.
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Unread postAuthor: django » Wed Aug 19, 2009 5:44 am

Sorry Guys,I'll try get some footage of this thing in action= I took it out last weekend to the Mother-in laws Farm and man I was impressed= first time ive been able to field test it out.

Easily flying through cans,bottles over 25 meters and pretty accurate for a home made job :D I shot some " other" targets too and yeh this thing is a killer to shoot. Pitty I can't run more PSI,double feeds or worse over that power unfortunately but overall Im pretty happy with it,im thinking of sleeving the barrel for more power.

Biggest downside,yes is ammo cost 20cents Australian per round!: Im trying to find a cheaper BB supplier
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Unread postAuthor: inonickname » Wed Aug 19, 2009 5:51 am

Eeew... I hate expensive ammo. I usually improvise what I have around.

Des-2 and the upcoming co-ax (730+ ft/lbs energy :shock: ) will usually just use custom made ammunition (turned slugs, I have around 10ft of stainless sleeved in copper- it's for earthing homes. Stainless on the inside and a thin layer of copper on the outside)..

Making them will be time consuming, even though it will cost me basically nothing.. So I'd still be on the lookout for suitable ammo.
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Unread postAuthor: poppamies » Thu Oct 22, 2009 2:45 pm

can somebody tell me waht is poppet valve? is it somekind of impulse valve?
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Unread postAuthor: jackssmirkingrevenge » Thu Oct 22, 2009 2:51 pm

poppamies wrote:can somebody tell me waht is poppet valve? is it somekind of impulse valve?



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Unread postAuthor: poppamies » Fri Oct 23, 2009 7:21 am

google didnt tell me!
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Unread postAuthor: POLAND_SPUD » Fri Oct 23, 2009 8:37 am

poppet valves are directional control valves... they function more less like spool valves but they are built in a slightly different way

directionally control valves can switch the direction of flow from one port to the other/others



spend some time reading the links.... some of them refer to hydraulics not pneumatics but they are useful as well

http://www.hydraulicspneumatics.com/200 ... aticValves

http://www.wisc-online.com/objects/inde ... ID=DCE9404

http://www.tpub.com/content/engine/1410 ... 105_99.htm

http://www.festo-didactic.com/int-en/se ... neumatics/
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Unread postAuthor: django » Sat Feb 06, 2010 9:31 pm

Damn!!!, My lovely gun is broken!? I thought the Poppet valve was faulty but its actually the Qev, not functioning for some reason. Because of the way my guns made its going to be hard to get at the Qev( bondo framework and internals puttied in) to see whats wrong!? its been fine all this time so I dont know whats wrong yet :( .
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Unread postAuthor: POLAND_SPUD » Sat Feb 06, 2010 10:00 pm

don't you have access to the pilot side ? there is a cap there that allows you to service them... I guess that there is no need to unscrew the whole QEV.. just unscrew the cap
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Unread postAuthor: django » Sat Feb 06, 2010 10:49 pm

I just made a mess taking the gun apart= pics later to clarify what I mean :cry: frame/bondo now needs redone( lots of work!)I took the cap off the QEV and can see no problem!?? the Diaphragm is fine, the small light spring is still inplace. lightly screwed it back together now it fires again!!, last night it was not wanting to fire ( one in every 3 shots) then just wouldnt fire at all like the qev was stuck but I cant see a problem!?.

I'll now have to alter the framework so i can take it apart from now on but It will not look as nice
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Unread postAuthor: POLAND_SPUD » Sat Feb 06, 2010 11:11 pm

the small light spring is still inplace
hmm so you are using a 2 way valve not a 3 way valve ?


I always wondered how you built that frame
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Unread postAuthor: Marffy » Sat Feb 06, 2010 11:42 pm

i like how it 9mm. it makes it sound real and stuff.
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Unread postAuthor: django » Sun Feb 07, 2010 12:08 am

POLAND_SPUD wrote:
the small light spring is still inplace
hmm so you are using a 2 way valve not a 3 way valve ?


I always wondered how you built that frame


The frame is wood thats carved out( took ages!) then a section of pvc + Bondo on the lower section infront of the trigger to hide the air chamber.
Im simply using a 1/4" Qev and chamber with a light spring pushing on the diaphragm and a 1/8" Poppet Valve( clippard MJVO-3, 3 way, Normally open)

as shown here
http://www.clippard.com/store/display_d ... sku=MJVO-3


EDIT: Still cant get the gun to fire anymore!? I hook up the Poppet by itself and it operates how it should( air comes out the port when I turn the on/off valve on my co2 bottle,press the button on the poppet, it closes air) I screw the poppet back into the QEV and it hisses air out the OUT port!?,diaphragm looks fine
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Unread postAuthor: django » Sun Feb 07, 2010 8:43 am

django wrote:
POLAND_SPUD wrote:
the small light spring is still inplace
hmm so you are using a 2 way valve not a 3 way valve ?


I always wondered how you built that frame


The frame is wood thats carved out( took ages!) then a section of pvc + Bondo on the lower section infront of the trigger to hide the air chamber.
Im simply using a 1/4" Qev and chamber with a light spring pushing on the diaphragm and a 1/8" Poppet Valve( clippard MJVO-3, 3 way, Normally open)

as shown here
http://www.clippard.com/store/display_d ... sku=MJVO-3


EDIT: Still cant get the gun to fire anymore!? I hook up the Poppet by itself and it operates how it should( air comes out the port when I turn the on/off valve on my co2 bottle,press the button on the poppet, it closes air) I screw the poppet back into the QEV and it hisses air out the OUT port!?,diaphragm looks fine
.

I just want my gun working again but fail to see why its randomly not fireing!??,worked on it all day and im stumped!?.I kept testing, got it working again,puttied it back in the frame then it stopped working again!,took it apart yet again did some more testing just now and its working for now. For months its worked fine but now its developed some random fault that I just cant pick! :roll:
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Unread postAuthor: POLAND_SPUD » Sun Feb 07, 2010 9:37 am

the point is that you don't need a spring there... remove it and check if it works
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