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silencer testing!

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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silencer testing!

Unread postAuthor: ALIHISGREAT » Sun Oct 28, 2007 10:04 am

today i built my silencer for my unfinished pnuematic paintball cannon, i use 3/4" pipe as an outer barrel with some b&q 22mm easyfit pipe as an inner barrel so i drilled some nice spiral porting on the innter barrel cut some plywood discs for the silencer ends and used 1.5" pipe as the body, it works well and reduces the volume and makes a cool tss sound and releases the vapour slowly which is really cool, now i'm off to try some wadding, would you recommend packing it loosly or tightly? and i'm planing on using cotton wool, will it be suitable?
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Unread postAuthor: hyldgaard » Sun Oct 28, 2007 10:10 am

With the ones i have experimented with, the tighter the wadding was packed, the more efficient it was, untill a certain point were it stopped working as a silencer.
My advice: try packing it tighter and tighter untill you find the point were it is most efficient :)
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Unread postAuthor: Zen/// » Sun Oct 28, 2007 1:22 pm

You can also use steel wool. 8)
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Unread postAuthor: knappengineering » Sun Oct 28, 2007 2:06 pm

I found that cotton batting(the one used for the insides of quilts) works well. It helps that my mom is into quilting. :lol: :D
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Unread postAuthor: ALIHISGREAT » Sun Oct 28, 2007 2:44 pm

cool thanks i will try with different densitys of cotton wool tomorrow! any other suggestions, also do you guys know what works better, baffles or wadding?
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Unread postAuthor: Novacastrian » Sun Oct 28, 2007 8:04 pm

ALIHISGREAT wrote:cool thanks i will try with different densitys of cotton wool tomorrow! any other suggestions, also do you guys know what works better, baffles or wadding?


Use both.
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Unread postAuthor: jackssmirkingrevenge » Sun Oct 28, 2007 8:55 pm

Novacastrian wrote:Use both.


Agreed, but if you have to choose, go for baffles.

cut some plywood discs for the silencer ends


cut a couple more et voila, le baffles ;)

You can also use steel wool.


I would recommend this for combustions where the steel wool helps to dissipate the heat of the propelling gasses and therefore lower the pressure, but for pneumatics softer, denser materials are a better idea.
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Unread postAuthor: Marco321 » Sun Oct 28, 2007 10:09 pm

What is more effective? A silencer with baffles and wadding but with it over the barrel and the barrel has holes or slits. Or a silencer with just baffles, but over the end so no barrel goes inside it.
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Unread postAuthor: Lentamentalisk » Sun Oct 28, 2007 10:40 pm

Marco321 wrote:What is more effective? A silencer with baffles and wadding but with it over the barrel and the barrel has holes or slits. Or a silencer with just baffles, but over the end so no barrel goes inside it.


the latter works great if your ammo is perfectly round and not coming out with lots of spin, but if it isnt round, it will instantly begin to tumble, causing it to get caught in the baffels.

My question. If you are using a barrel shrouding method, covering the entire barrel, but only with holes in the last foot, then should you use wadding, or just let it act as a pressure dissipating chamber with nothing in it?
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Unread postAuthor: jackssmirkingrevenge » Sun Oct 28, 2007 11:58 pm

Marco321 wrote:What is more effective? A silencer with baffles and wadding but with it over the barrel and the barrel has holes or slits. Or a silencer with just baffles, but over the end so no barrel goes inside it.


Ideally there is no contact with the projectile in the silencer. Looking at firearm silencers, the only times when a perforated barrel is used is in the case of shotguns, where the sabot opening up in the silencer would destroy the baffles, and when gas needs to be bleeded off to slow down the projecile like with the MP5SD. As mentioned above, spudguns rarely use stable enough ammo to dispense with the perforated barrel, unless you're shooting BB or similar spherical ammo.

If you are using a barrel shrouding method, covering the entire barrel, but only with holes in the last foot, then should you use wadding, or just let it act as a pressure dissipating chamber with nothing in it?


To get a pure volumetric silencer, it would have to be so large that it would be impractical. In practice, silencers are almost always smaller than they should be, so they need all the help they can get - so wadding is a good thing :)
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Unread postAuthor: Marco321 » Mon Oct 29, 2007 12:22 am

Thanks again Jack.
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Unread postAuthor: Lentamentalisk » Mon Oct 29, 2007 12:22 am

jackssmirkingrevenge wrote:
If you are using a barrel shrouding method, covering the entire barrel, but only with holes in the last foot, then should you use wadding, or just let it act as a pressure dissipating chamber with nothing in it?


To get a pure volumetric silencer, it would have to be so large that it would be impractical. In practice, silencers are almost always smaller than they should be, so they need all the help they can get - so wadding is a good thing :)

I'm talking about a 1/2"x4' barrel shrouded in a 1.5"x4', for a 1.5"x2' chamber... would that still hold true?
Wouldn't the wadding greatly decrease the ability of the air to flow into it?
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Unread postAuthor: jackssmirkingrevenge » Mon Oct 29, 2007 12:32 am

Assuming you're using 100 psi, then your shroud diameter would have to be increased to 2.75" for ideal volume.

Wouldn't the wadding greatly decrease the ability of the air to flow into it?


The air coming out of your barrel makes noise because it's travelling fast - the more you slow it down, the less noise it will make. Assuming it's not too tighly packed, air will flow through the wadding and because of the drag that it causes, will lose velocity while doing so. The downside is that finding the right density of wadding for ideal results would take a lot of trial and error.
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Unread postAuthor: ALIHISGREAT » Mon Oct 29, 2007 2:45 am

its very hard to get the ideal volume, although i should get close to it on my 6mm sniper's silencer.

[url]cut a couple more et voila, le baffles
[/url]

but the silencer ends are a bit too small because i have no imperial hole cutting drill bits so i just wrapped the ends in masking tape and duck tape to seal them.
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Unread postAuthor: jackssmirkingrevenge » Mon Oct 29, 2007 2:52 am

As suggested earlier, you can purchase some balsa wood and cut it easily using a craft knife, that will give you lightweight yet strong baffles (especially if you laminate two discs together with perpendicular grain direction)
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