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shut-off valve suppressor

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Unread postAuthor: POLAND_SPUD » Sun Feb 26, 2012 4:57 pm

slide valve & You can't really hear the difference between shut off removed (first shot) and added (second shot). The shut off is clearly working though, you can hear the "fshhhhhh" sound of the air leaking out after the second shot. At such low pressure the the pilot being vented also makes a bit of noise
that's the biggest disadvantage of slide valves - they don't have threaded exhaust ports
so forget about perfectly silenced pneumatics if you can't attach another one to the exhaust[/quote]
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Unread postAuthor: wyz2285 » Sun Feb 26, 2012 5:12 pm

that's the biggest disadvantage of slide valves - they don't have threaded exhaust ports
so forget about perfectly silenced pneumatics if you can't attach another one to the exhaust

My semi system does not have this problem, the quantity of exhaust air is too small and can be effectively suppressed by the handle with a slight modification :wink:
I´m gonna build my own once I got time :twisted:
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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 Feb 27, 2012 1:48 am

POLAND_SPUD wrote:forget about perfectly silenced pneumatics if you can't attach another one to the exhaust


A detent pop-off or QDV style valve would not have the exhaust problem, and be more efficient ;)

In fact this design promises to work best with elongated projectiles, are you there Petitlu :D
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 27, 2012 1:20 pm

Hybrid test at 8x, fail. The BB lodged in the insert tube and blew it out. Clearly I'm going about this the wrong way in terms of the usual underengineering, as well as not incorporating an expansion chamber in order to lower stress on the BB.

Looking at the high speed footage though, I have one niggling doubt. I filmed it originally at 420 fps and then slowed it down even further:

[youtube]http://www.youtube.com/watch?v=-4PHkQAkLwI&feature=plcp&context=C327d0a9UDOEgsToPDskKpCjATUAwqv2zOgXjoWzv9[/youtube]

You can definitely see something going into the hole after the paper is blown away, and to me it looks much more like a lead pellet than a brass tube with a BB embedded it. As well as that, the pellet simply bounced off the wooden backstop so nowhere near the penetration I would have expected.

I'm forced to conclude that the BB/tube combination blew out before the pellet. Thoughts?

Here's the aftermath, note the discolouration on the paper:
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Unread postAuthor: wyz2285 » Mon Feb 27, 2012 1:57 pm

I'm forced to conclude that the BB/tube combination blew out before the pellet.

If that happened, it´s obvious that the bb is blew out.
Maybe because the barrel isn´t tight enough comparing to the lead pellet, also the pellet maybe too heave and a considerable quantity of gas were able to passed though it and shut-off the suppressor.
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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: Brian the brain » Mon Feb 27, 2012 2:29 pm

I'm forced to conclude that the BB/tube combination blew out before the pellet. Thoughts?


Possible.
So far we have learned that it needs to be stronger or the pressure acting on it should be lowered.

We won't know if it's any good unless you add an expansion chamber to it.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 27, 2012 3:05 pm

Brian the brain wrote:We won't know if it's any good unless you add an expansion chamber to it.


A major problem I'm seeing aside from the strength of the system is that the exit hole is identical to projectile diameter, and there is only 0.5mm difference between ball and projectile.

I'm thinking the next step should be a smaller diameter version, say 3 or 4.5mm, if I'm stuck with a 6mm BB as a blocker.
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Unread postAuthor: Brian the brain » Mon Feb 27, 2012 3:57 pm

Sounds like a plan!

Another option would be to try a metal bb.
Won't hurt to try.
Won't hurt me anyway... :D
It certainly won't clog up the exit too soon.

Dang!
You should've muffled the slide valve earlier.

I hope this doesn't turn out to be another long time quest like the full-auto-valve
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 27, 2012 4:23 pm

Brian the brain wrote:Another option would be to try a metal bb.
Won't hurt to try.
Won't hurt me anyway... :D
It certainly won't clog up the exit too soon.


That's a good point, if the BB is indeed being picked up too early then a heavier BB will certainly help to mitigate this. My worry is that it would not be picked up by the gasses at all.

Dang!
You should've muffled the slide valve earlier.


Well if it doesn't work for high mix hybrids then it's not worth trying ;)

I hope this doesn't turn out to be another long time quest like the full-auto-valve


Not really, as discussed in private I have made other systems work very well, so this is just an interesting alternative. Also, these days thanks to my machine investments prototyping is a lot less painful ;)

edit: going for a prototype with an expansion chamber and an 8mm steel BB as a blocker, keep watching this space ;)

edit II: done, testing tomorrow.
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Unread postAuthor: POLAND_SPUD » Mon Feb 27, 2012 7:17 pm

if the BB is indeed being picked up too early then a heavier BB will certainly help to mitigate this
lol can't you machine it out of acrylic and see for yourself if it's being picked up earlier or not? :wink:
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 28, 2012 2:23 am

Unfortunately the only place I can buy acrylic here only opens in the mornings so I haven't yet been able to stock up. Also it will be interesting to see if being exposed to a hybrid mix will actually reduce its transparency. Certainly in the clear tennis ball launcher the combustion mix didn't affect it.

Here's what the current prototype looks like inside, with a 5.5mm barrel, 8mm ball bearing blocker and 7mm muzzle opening. Instead of being in a tube, the ball rests between the two front baffles like this.
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 28, 2012 2:45 pm

No joy with this one, as suspected the heavy steel bearing wasn't picked up by the gasses...

I'm calling this one plausible, but it needs tweaking.
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Unread postAuthor: warhead052 » Tue Feb 28, 2012 2:54 pm

Jack, you can order plastic 8mm airsoft bbs. They are made for the larger bore airsoft guns, not as common, but they are available.
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 28, 2012 3:39 pm

I said it needs tweaking, not that I'd be doing the tweaking ;)
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Unread postAuthor: warhead052 » Tue Feb 28, 2012 4:00 pm

Haha, I may give it a try. It looks like it is possible, considering your video of the qev slide combo with the suppressor. I think what you were hearing was the exhaust of the slide valve, try it with a silenced pilot valve.
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