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constant flow 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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constant flow full auto :)

Unread postAuthor: jackssmirkingrevenge » Tue Jan 06, 2009 10:51 am

The older members will remember my quest for a full auto valve from a constant air supply that sometimes were epic fail and other times came closebut not quite.

I've long been a proponent of self-made fittings, but recently spotted a couple of adjustable safety valves and decided to buy them for the heck of it to see what they could do. Long story short, I hooked one up to a blowgun attached to my compressor and after tweaking the spring tension a little:

[youtube]http://www.youtube.com/watch?v=13BHdjUD69Y[/youtube]

I think it's safe to say you can expect another attempt at an auto project pretty soon :D
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Unread postAuthor: POLAND_SPUD » Tue Jan 06, 2009 11:01 am

so when are you going to turn it into a gun...

I've never really undestood your persistence with all this constant flow thing... could you explain what are main advantages of it or how powerful gun you can buld with it??

BTW you should have titled the topic as 'I has constatant flow fullauto' :wink:
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 06, 2009 11:26 am

POLAND_SPUD wrote:so when are you going to turn it into a gun...


It exhausts from two slots, all I need to do is block off one of them and attach the other to a blow-forward breech, given the joys of epoxy casting that shouldn't be too much of a chore :)

I've never really undestood your persistence with all this constant flow thing... could you explain what are main advantages of it or how powerful gun you can buld with it??


I suppose it's carried over from starting out with cloud or vortex BBMGs, where all you need to do is inject air from a blowgun into the system et voila, full auto. While the rate of fire is obviously less, incorporating some sort of "pulse" valve into the loop will usually give you the benefit of faster opening time and more flow.

The valve has 1/4" porting so it should be perfect for a 6mm BB/pellet machinegun :)
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Unread postAuthor: jitup » Tue Jan 06, 2009 11:36 am

very cool. maybr I will give something a try (maybe not, I am working on quite a few things)
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Unread postAuthor: ALIHISGREAT » Tue Jan 06, 2009 12:11 pm

sounds pretty cool, although i suspect performance won't be mind blowing, hopefully the flow is adequate for airsoft bbs though?
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 06, 2009 12:14 pm

ALIHISGREAT wrote:hopefully the flow is adequate for airsoft bbs though?


That's what I'm hoping, working on a way to attach it to an existing 6mm blow-forward breech as we speak :)

Here's what it's looking like, one port blocked off and a flattened brass tube on the other port to feed into the breech, all that's left is to encase it in epoxy for strength and we should be good for testing in 24 hours :)
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Unread postAuthor: psycix » Tue Jan 06, 2009 3:28 pm

Impressive!
So easy and yet you converted a constant flow to a pulsed one.

On the valve you used:
What kind of safety valve is it?
What is it normally used for?



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Unread postAuthor: ALIHISGREAT » Tue Jan 06, 2009 3:56 pm

we should be good for testing in 24 hours


hopefully this one won't explode :wink: :D
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Unread postAuthor: PVC Arsenal 17 » Tue Jan 06, 2009 4:38 pm

Saladtosser did this many moons ago.

A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.

Wow... I was an idiot back when Atlantis posted this...
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Re: constant flow full auto :)

Unread postAuthor: THUNDERLORD » Tue Jan 06, 2009 4:54 pm

jackssmirkingrevenge wrote:The older members will remember my quest for a full auto valve from a constant air supply...

...I think it's safe to say you can expect another attempt at an auto project pretty soon :D


I almost forgot :roll:

I hope you keep us posted.
Just ducked into an internet connection, and with earphones, the sound effect is awesome when played in combination with this!
Anyway, I'll be waiting for the follow up on this
BTW, more details on the safety valve, where can I get one ?
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Unread postAuthor: iknowmy3tables » Tue Jan 06, 2009 5:12 pm

PVC Arsenal 17 wrote:Saladtosser did this many moons ago.

A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.

Wow... I was an idiot back when Atlantis posted this...


using a saftey relief valve as a pilot has been done plenty of times before, and it's also been used as a pilot for full auto, but this is different it's just using the relief valve as a pulsing valve for a full auto bbgun, previously this has not been done before because of difficulties in making the valve pulse while maintaining a strong output in those pulses, but If jack's has tweaked this right then there is a lot of potential for this

edit:
BTW Jack you have pretty good craftsmanship, but for me I find getting the back of the bolt alined to pop in and out of the input pipe tricky so I'm recommending this design
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 07, 2009 12:31 am

PVC Arsenal 17 wrote:Saladtosser did this many moons ago.


Not quite the same thing is it though, he's using the pop-off as a pilot. The guy who had done something similar to this was Brian the brain with his snap valve.

A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.


I'm quite confident it will, it does move a lot of air - you can see the blowgun recoiling in the video - and we're talking 1/4" porting for a 6mm barrel.

The valve was purchased off eBay so is no longer listed, but it's nothing special, works just like any other pop-off only the top is threaded to allow you to adjust the spring tension. alternatively one could buy a standard pop-off with a fixed pressure and change springs.

BTW Jack you have pretty good craftsmanship, but for me I find getting the back of the bolt alined to pop in and out of the input pipe tricky so I'm recommending this design


Good idea there but for now I'll be using the one I made here ;)

Image

and it should work something like this:

Image

*crosses fingers*

hopefully this one won't explode


wanker. :D
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Unread postAuthor: i-will » Wed Jan 07, 2009 1:55 am

so how strong is each air burst? that recoil kinda gives me an idea. what kinda fps do u think u'll get with 6mm barrel and 0.2g bbs? i trust that u've been doing this kinda thing long enough to give a reasonable estimate. i'm sorry if u think this is a dumb question.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 07, 2009 1:59 am

No clue what performance will be like to be honest, but I'm very optimistic. Now that it's directed through one port only it should be pretty significant. Can't wait to get home and have a play with it, I'll post results as soon as I have them :)
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Unread postAuthor: frankrede » Wed Jan 07, 2009 7:57 am

This looks to be promising, and with an even better blowgun you could maybe up the pressures?
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