I too has semi-auto

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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jor2daje
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Fri May 21, 2010 12:18 am

umm it seems a litttle underkill for a 3/4" the flow through them is alright but the holes look to only be about 1/16".

also update with some videos shooting up acrylic.
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Crna Legija
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Fri May 21, 2010 1:34 am

maby with a realy small id do with a 1/4 tho
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POLAND_SPUD
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Fri May 21, 2010 1:58 am

I think that clippard's MJVO-3 valves might have enough flow to pilot a 3/4" QEV... but I can't get them in europe so you might want to ask PVC_arsenal to test it for you

MJVO-3 valves have ~800 l/m of flow while most 1/8" DCVs have about 200 - 300 l/m
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michaelgohjs
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Fri May 21, 2010 6:28 am

emm i m sorry but i dont really get the idea of how this works.. maybe an animated gif or some explaination..i dont understand the ev and 3 way valve part
django
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Fri May 21, 2010 7:44 am

Wow man great work,I love this design =I have been thinking of making another semi auto myself and this design looks like a winner! 8) . My current semi is ok but too big so I need to make another thats much smaller than my huge Pitbul 9 rifle,I want to make it as compact as possible for transporting it about seeing as these things are HIGHLY illegal here in Australia. Dont know if I can make this design compact enough for what I have in mind?: like a small P90 design

I might use your design ( if thats ok?)but instead again use one of those great little 1/8 MJVO-3 Poppet Valves as per my current Semi, though those pnuematic cylinders are insanely expensive here!!??. what psi are you running through this beast?

GREAT WORK
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POLAND_SPUD
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Fri May 21, 2010 8:53 am

lol no offence but this design has been first used by PVC_arsenal IIRC... then at least 3 or 4 other people has built something similar
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Lockednloaded
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Fri May 21, 2010 9:36 am

how do you seal the pneumatic cylinder? is it just a tight fit or do you have a floating o-ring seal?
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django
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Fri May 21, 2010 5:44 pm

POLAND_SPUD wrote:lol no offence but this design has been first used by PVC_arsenal IIRC... then at least 3 or 4 other people has built something similar
Well I'm pretty much a lurker here most of the time,thats my excuse anyways :D
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POLAND_SPUD
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Fri May 21, 2010 5:53 pm

lol you might say that I am a bit envy but I am envy...

IIRC I have posted just one gun here (well ok 2 but they are very similar) and it used the same principle as this one... I talk about it all the time, damn I even talk about DCVs all the time, which are closely related to this... and yet ppl are like 'wow that's a great idea dude'
:shock:
[/envy&ranting]

lol I realize it was pathetic...
ok enough hijacking :D
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jor2daje
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Fri May 21, 2010 8:09 pm

@michael, did yo look at the pictures on the first page, I think they explain it quite easily.

and ya im definetly not the first one to come up with a design like this, I think pvc aresenal and btrettl both use something like this in their nerf guns, and poland spud and others have used this on a larger scale.

@lockednloaded what do you mean seal the cylinder? in the barrel it seals just because it is a really good fit.
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Gun Freak
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Fri May 21, 2010 8:16 pm

I think he means behind where it pushes the ammo where it goes into the barrel.
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Lockednloaded
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Fri May 21, 2010 8:22 pm

jor2daje wrote: what do you mean seal the cylinder? in the barrel it seals just because it is a really good fit.
Thats exactly what i was asking, thanks. does a lot of air escape out of there? because if you make it air tight you may see an increase in power
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Gun Freak
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Fri May 21, 2010 8:24 pm

Try a small o-ring with some lube, I agree with LnL, you may get a small boost.
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jor2daje
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Fri May 21, 2010 8:53 pm

it seems really pretty good seal, i may put a little flour behind just to see how much escapes but I dont feel much and my face is pretty close to it when Im shooting :D
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Lockednloaded
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Fri May 21, 2010 8:57 pm

I've got a good idea for sealing in my scaled up gun; i will epoxy an o ring in a bushing and the rod will slide in and out of that. any ideas for a good lubrication, I'm thinking graphite
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