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6mm Full-auto

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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6mm Full-auto

Unread postAuthor: wyz2285 » Sun Nov 04, 2012 2:48 pm

I thought I´d like to have a QEV+pop off full auto as well, so I bought a pop off and modified a QEV to use it.
It was very un-reliable, so I looked for a better pilot valve, The BTB snapvalve
Guess what, it worked :twisted:
By adjusting the spring tension, I can have different ROF and power (high ROF low power or low ROF high power).
It rocked off the blow-forward bolt and barrel :lol: so I didn´t get a chance to shot it :roll: but soon...
[youtube]http://www.youtube.com/watch?v=z9dmmX9Krfk&feature=g-all-u[/youtube]
Now:
I want a blow-back reloading system, but got a problem: How do I keep the bolt shut when the projectile is inside the barrel and open the air reach the piston that is attached to the bolt? Take a look at the diagram you will know that I´m talking about.
I think I will need to find the right spring and play with the area differential between the bolt (barrel ID) and the piston (what ever needed :lol: for the system to work). Or some short of lock system, I had one in mind but kind complicated for my taste :P
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 04, 2012 4:47 pm

Looking good there wyz!

The only shame is the amount of air you're wasting through the pilot, it would be cool if that could be channelled into a reloading mechanism to do some useful work. I say that if you've gone through the trouble of making a "snap valve", think about using that as the main valve instead of just a pilot.

As to your blowback mechanism, drawn as it is it would actuate before the projectile left the barrel. Instead of a bolt, I would close the breech hole with a sleeve so it is unaffected by barrel pressure, I had drawn this up a while ago:

Image

I drew it with cartridges but you could leave these out if you catch my drift. This is how the FX Monsoon works, it needs 100 bar but at the same time that's because it also has to cock a hefty hammer spring which in your case doesn't apply.
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Unread postAuthor: wyz2285 » Sun Nov 04, 2012 6:02 pm

Good idea, I'll try out and see how bad would the leak be.
Yeah I'd love to use the pilot air for something, but it happens the same time as the opening of the QEV... Wait, I could use it to actuate a push forward bolt, so no power will be lost by the blow forward bolt :idea:
To the drawing board!
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 05, 2012 12:29 am

Yes, I can see that working... just make sure that the pilot air is pushing on a piston with a larger diameter than the barrel in order to make sure the air coming from the QEV doesn't blow it back.
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