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Reinforcing Copper Pneumatic?

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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Reinforcing Copper Pneumatic?

Unread postAuthor: KamranGo » Fri Feb 08, 2008 7:58 pm

Hey guys, I was interested in building my first copper gun (ideally it will be pretty small, compact, have a breach-loading or interchangeable barrel system, and probably will shoot marble sized projectiles) because it can be pressurized to higher PSI's than regular PVC. The only thing that I worry about is that since copper can be pressurized to such extreme PSI's, and because it is also quite malleable (easily dented and thus weakened) I feel as if I would be essentially holding a small pipebomb when i go to fire it. Is there any way to reinforce the copper externally that might prevent/catch/slow shrapnel in the event of the gun failing? Or at least to protect the copper from being vulnerable to external damage?

Or is this really a pretty irrational fear to have? I'm not familiar at all with working with the material, so I don't know if it requires any special tools or if it is much more difficult to work with than PVC.

On another note, I know with PVC most people don't go much above 125 PSI when pressurizing their guns. However, with copper i've seen some pretty extreme ranges used on these forums. Given that this will be my first copper gun, what PSI do people recommend I set as my max PSI so that I will be well within the maximum pressure capabilities of the materials?
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Unread postAuthor: paaiyan » Fri Feb 08, 2008 8:04 pm

It's a fairly irrational fear I'm afraid. As long as you're using safe pressures you're fine. As far as I know, pressure rated pipe is rated for a reason. As for max pressure, the max pressure they put on the pipe is actually well below the burst pressure, so you're actually safe a tad above the listed pressure.

But if you're feeling cautious, just don't go above it. I don't really know of a way to make it safer in the event of a catastrophic failure though.
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Unread postAuthor: bigbob12345 » Fri Feb 08, 2008 8:05 pm

For copper the max pressure I would use in type M is about 300psi type L 400psi type K 600psi.I know thats under what they are rated but you always want to maintain a large safety margin.
BTW your avatar is really weird
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Unread postAuthor: Necrosis » Fri Feb 08, 2008 8:18 pm

The fear of death is an irrational fear.
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Unread postAuthor: paaiyan » Fri Feb 08, 2008 8:19 pm

Necrosis wrote:The fear of death is an irrational fear.


... Not quite what I was getting at.
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Unread postAuthor: Necrosis » Fri Feb 08, 2008 8:25 pm

From what I have seen on the discovery channel, pressure rated pipes are tested to about 3 times their operating pressure before they are let out.

But the discovery channel might be wrong.
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Unread postAuthor: paaiyan » Fri Feb 08, 2008 8:26 pm

I don't know how much higher they are tested, but I do know it's a significant amount higher. Enough to make me feel safe.
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Unread postAuthor: Hawkeye » Fri Feb 08, 2008 8:28 pm

Make sure you use clean unblemished pipe to start with and then make a shell for it that will protect it in the event of dropping it or dinging it against something.
You could make a nice shell from good quality wood.
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Unread postAuthor: bigbob12345 » Fri Feb 08, 2008 8:29 pm

The fear of death is not an irrational fear
Hey guys guess what Im going to go take some DWV pvc up to 1000psi and hold it next to my head because the fear of death is irrational.
Yeah thats why the fear of death is not irrational because if you think it is
YOU WILL DIE.
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Unread postAuthor: paaiyan » Fri Feb 08, 2008 8:31 pm

Going off-topic but actually, the fear of death is quite irrational. Everyone dies, there's no point in being afraid of it. You can't live your life in fear of death, or you won't be living at all.

That's all I've got to say
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Unread postAuthor: Necrosis » Fri Feb 08, 2008 8:32 pm

We all die in some point in our life, so fearing it is futile.

But it was more of a joke than anything really, Don't be in a rush to live...

edit The cake hatted bunny beat me to it.
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Unread postAuthor: bigbob12345 » Fri Feb 08, 2008 8:37 pm

paaiyan wrote:Going off-topic but actually, the fear of death is quite irrational. Everyone dies, there's no point in being afraid of it. You can't live your life in fear of death, or you won't be living at all.

That's all I've got to say


That is true but I think you have more to live for if your 20 than if your 90.If you are 90 I would agree with that statement because you never know when your going to go to sleep and not wake up.But if your 20 do you just want to see if you can jump across the grand canyon no you do that when your 90.
And this is completely on topic Im just questioning the answer to the question asked.
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Unread postAuthor: Necrosis » Fri Feb 08, 2008 8:47 pm

For the other question, you do need special tools for copper (or metal in general).

You'd need a metal file, a soldering torch , a metal saw, and some soldering tin (maybe some soldering acid too).

Or if you want to use screw on fittings you could leave out the soldering stuff, but solder fittings are much cheaper and they in fact, are stronger.
But they require some skill to fuse together.
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Unread postAuthor: peeeto » Fri Feb 08, 2008 8:53 pm

:roll: ...gettin back on topic, just make sure you include a safety valve on you r pressure chamber - you can order them to popoff at different pressures. if you lose sleep about that one being off-spec or defective, put 2 of em on.

wood surround is a good idea too (i.e. stock ;)

also, McMaster has a good selection of larger copper tube (pipe) --> smaller male NPT thread couplings (for example, 1-1/4" pipe socket to 3/4" male NPT) what dia. copper do you plan on for the chamber?

[edit - added:] i'm using 1-1/4" dia. - i found it to be expensive and a little hard to get.

at L*wes or H*me Dep*t, it's about $80 for a 10' length for Type L, and they don't sell it by the foot. at McMaster's, the cheapest you can get is a 2-ft length of Type M for $19... i found a local hardware store that sells Type M for $6/ft. when i went in to buy, i asked for 2 ft and they had a 35-1/2" length that the guy gave to me for the price of 2 ft :)

those little hardware stores (lol Ace hardly little) have saved me so many times when i need a small part or small quantity of something (sadly, not such a great selection of brass fittings, though...)
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Unread postAuthor: paaiyan » Fri Feb 08, 2008 10:21 pm

Any particular reason you were putting *'s for O's in Lowes and Home Depot?
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