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I need help with plans

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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Unread postAuthor: BrianMigs » Sat Feb 02, 2008 5:50 pm

Is there a thread or something somewhere that will show me what all these different parts look like?
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Unread postAuthor: daberno123 » Sat Feb 02, 2008 5:51 pm

Hey whaddya know, I have a 3" to 1" bell reducer on my cannon, crap. LOL

I have taken it up to 70PSI multiplt times, do I have a ticking time bomb?



no probably not. I actually used 4" to 1" bell reducers on one of my guns and took it up to 100 psi probably over 60 times without it failing. I eventually saw they were DWV and replaced them with bushings. Still, change them to bushings for safety.
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Unread postAuthor: iknowmy3tables » Sat Feb 02, 2008 5:57 pm

even the brushing you have to be careful, truth is most of us are screwed when it comes to buying any parts above 2" in sch 40 you might find an end cap if your lucky be sure to read the label on the rim
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Unread postAuthor: MrCrowley » Sat Feb 02, 2008 6:06 pm

BrianMigs wrote:Is there a thread or something somewhere that will show me what all these different parts look like?


Not really.

I'll list a few pressure rated fittings in pictures:
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Unread postAuthor: schmanman » Sat Feb 02, 2008 6:49 pm

MrCrowley wrote:
schmanman wrote:
MrCrowley wrote:Just a warning, Sch 40 doesn't mean it's pressure rated. It's a thickness rating, not a pressure rating.

What you need to look for is 'NSF-PW' on the pipe or fittings, which is always pressure rated.


I love it how crowley knows more about our plumbing system than most americans do.

I find it humorous. :P


I get it from you guys, so you better be right :)

'Spose it's like a language, and you just pick it up as you go.

And it's very handy if you speak the native language of the country you reside in, if you know what I mean.


Some guy at a hardware store yesterday was trying to sell me this crappy car compressor, he said he used it on forklift tyres, which are (according to him) very high pressure.

I ask how high it pumps, (while catching a glimpse of '250PSI' written on the box) and he said, 'oh about 300BAR'.

I just started laughing and asked if he knew his BAR and PSI, he said he did and kept saying forklift tyres are very high pressure. Then I told him 300BAR is about 4500psi, which you need hydraulic fittings for and i'd like to see a plastic pump get 1/10th that.

It still had no effect on him, he must not realise how high of a pressure 4500psi is, and the box of the pump had '250PSI' written about 10x all over it.




yep, It is like going to france when you speak no french. (which I did in 4th grade, all I can say is JESUS CHRIST!) sorry if that offended anyone.

If you are going to be one of the top posters on a mainly american site, you had probobly better know the pipes and such.




ha! I have a story like that!

when I was building the swat, nobody belived the valve was going to work. heck, nobody thought a sprinkler valve would work with air. I even went to a place that builds pneumatics systems for the major american automakers, and the u.s government! they said no too.

shows what they know.
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Unread postAuthor: DYI » Sat Feb 02, 2008 7:45 pm

You get stuff like that everywhere. There's a local radio station where I live trying to convince people to fill their tyres with nitrogen in the winter because it "doesn't expand and contract with temperature changes like air does". It makes me wonder whether they're thick enough to believe it themselves, or if they're just having a good laugh fooling the ignorant masses and making a pretty penny doing it.

And then there's the plumber saying that 3" Type M copper tube can't take 250 psi... When it is rated for 435 psi, and has a burst pressure of over 2.5kpsi.

People at my local hardware stores, however, are fairly intelligent, as is the local welder. They've caught on to the concept of piston valves, triggered burst disk valves, and hybrids as soon as I explain them in most cases.

And to the original poster, I think you need to make a DWV launcher and run it on O<sub>2</sub>/C<sub>2</sub>H<sub>2</sub>, and see what happens. Then you can make the contribution of an interesting video of you and your launcher getting pwned, rather than signing up to ask a question that you could have answered for yourself simply by using the search function.
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Unread postAuthor: Ragnarok » Sat Feb 02, 2008 8:08 pm

pizlo wrote:We should compile all of this into a "bible" and make newbs read it.

That's what the spud wiki is supposed to do. Doesn't really work.

I think we all have stories about different pieces of misinformation that people have.

I don't have one strictly about pipe materials, but a favourite of mine was the occasion when we'd whisked a launcher down to the local Army Cadet detachment back when I was still a member.
One of the other cadets volunteered to be shot on the principle that vegetable matter couldn't possibly be dangerous. It was suggested he might like to see what the effects were on an inanimate target first, and he should make his decision after seeing that... suffice to say, he no longer felt like being shot with it.

The language analogy is a good one, but first, I've been reminded of those appalling Nissan Micra ads that combined words, and called it speaking Micra - for example, simple and technology became "Simpology".
The Micra has also been described as shiny and bright, and that would become... wait a minute.

It's quite accurate, because when you first start, it's a bit like trying to communicate by just speaking louder and slower - I think a lot of people get that, as evidenced by the "halp i want 2 build a sniper i have no idea where to start" type posts.
You get people with a good basic understanding, a bit like lower school French. Some people take it to High school level, and that's the level of the semi-regulars, people that will drift in and out.
There are your "experts" - the people who are pretty fluent, perhaps native speakers. If you gave these people the right materials, they could build any type of launcher without breaking a sweat, and without needing to look for plans. (I'm tri-lingual. I've grown up speaking English, bad English* and engineer.)
Then you get people like JSR, who makes up his own words when a regular one isn't good enough for him, but he then pronounces them wrong. :D

Now, the question is, do you speak Potato?

*Ok, I stole this joke. What I actually speak is a language I created entirely from scratch, and it has all kinds of defining features. Only two people in the world speak it, but my friends have realised it's normally just used for swearing and insulting people.
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Unread postAuthor: pizlo » Sat Feb 02, 2008 8:24 pm

Vioshe
That is yes in the semi developed language of my friends :wink: I don't really think it was meant to be typed.
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Unread postAuthor: Ragnarok » Sat Feb 02, 2008 8:47 pm

It's a heck of a lot more complex than that. A simple yes changes depending on your gender and who you are speaking to.

These are phonetic pronunciations, the written form is slightly different.

Arcne is the basic form of yes.

That becomes Arcnou if you are a male talking to a social superior or being polite, Arcno when speaking informally to a peer, Arkneh (further back in the throat) if you are using it in a dismissive or derogatory form, and just Arc if you are responding to your name or that someone has your attention.

If you're female, there is yet another list of the forms.

A member of the opposite sex isn't considered a peer in conversation, it is typical to use the polite form, if talking to a group - you have to use the majority gender (which can make a strange conversation if someone keeps moving in and out of the room), etc, etc.

I didn't make it simple. I took all kinds of interesting linguistic features from different languages and mashed them all together. I should probably write the whole language down some time.
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Unread postAuthor: BrianMigs » Sat Feb 02, 2008 11:33 pm

so it is possible to get a 3" to like 1-1/2" bushing reducer or whatever it is at my local hardware store correct?

That, and my male adapter to my elbow are the only DWV parts on my gun.
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Unread postAuthor: MrCrowley » Sun Feb 03, 2008 12:22 am

I doubt your local store will have a 3"-1.5" bushing.

You may have to order one of www.mcmaster.com
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Unread postAuthor: jimmy101 » Sun Feb 03, 2008 1:55 pm

I'm surprised no one mentioned that there is a good possiblity that the reason the gun destroyed itself is because it had dual chambers.

In general, multiple chambers are a bad idea. You really should try to get to the same chamber volume with a single chamber. All the mutliple chambers do is add extra fittings (which decrease air flow) and shift a bunch of the weight of the chamber off the barrel's axis, which is not good.

If you are doing multiple chambers you have the same strength problem that over-n-under guns have; you have take care of the recoil energy of the barrel. If you don't the gun will rip itself apart, particulary with heavy ammo.

Multiple chamber gun can certainly be built, Joel made a couple very large guns with multiple chambers, but you have to do something to strengthen the design. PVC fittings, even if they are pressure rated, were not designed to take shearing loads.
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Unread postAuthor: jimmy101 » Sun Feb 03, 2008 1:59 pm

MrCrowley wrote:I doubt your local store will have a 3"-1.5" bushing.

You may have to order one of www.mcmaster.com

Your local store may have 3"-2" and 2"-1.5" bushings.
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 04, 2008 2:28 am

Ragnarok wrote:Then you get people like JSR, who makes up his own words when a regular one isn't good enough for him, but he then pronounces them wrong. :D


Such are the perils of working on the cutting edge of language, some words are bound to fail :P but it's a bit like the way evolution works, throw as many solutions as you can at the problem at hand, one of them is bound to work sooner or later :p
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Unread postAuthor: BC Pneumatics » Mon Feb 04, 2008 5:17 pm

Of course, there is one way to get into the hobby that is both cheap and safe:
http://www.bcarms.com/product_info.php?products_id=93
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