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The [Insert safety concern here] Cannon.

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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The [Insert safety concern here] Cannon.

Unread postAuthor: Intel Xeon » Sat Mar 17, 2007 10:02 pm

Ok, so this was my first cannon attempt and I say that the attempt kinda succeeded. Modded Rainbird Sprinkler Valve, 2"ID 25" sch40 chamber. Interchangeable 2"ID 10" long and 3/4"ID 4' long sch 40 barrels.

Working pressure of 75 psi with "t3h b!k3 pu^^p uv d00m"

Taht ish lyke teh nuubs kanon!

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My cannon is a wannabe gangsta'


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Unread postAuthor: frankrede » Sun Mar 18, 2007 12:10 am

that gun has DWV fittings not made for pressure but it should be fine at under 75psi.
But from what I see you have potential in this hobby.
I can tell you did (some) of your homework.
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Unread postAuthor: schmanman » Sun Mar 18, 2007 7:58 am

nice job on your first. really short 2" barrel though, go longer.
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Unread postAuthor: Intel Xeon » Sun Mar 18, 2007 8:05 am

everything is actually sch40 except for the 2" barrel couplings (which actually are just sleeved over the pipe,I removed the lip inside) and the coupling that attaches the cleanout. So, if anything fails, the only problem will be the cleanout shooting back, correct?
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Unread postAuthor: imablackskater » Sun Mar 18, 2007 9:01 am

nice first you should be alright at 75. by the way what do you shoot
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Unread postAuthor: mark.f » Sun Mar 18, 2007 1:43 pm

Nice "barrel flex-preventative system". 8)
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Unread postAuthor: Pete Zaria » Sun Mar 18, 2007 2:00 pm

Intel Xeon wrote:everything is actually sch40 except for the 2" barrel couplings (which actually are just sleeved over the pipe,I removed the lip inside) and the coupling that attaches the cleanout. So, if anything fails, the only problem will be the cleanout shooting back, correct?


Sch40 is a wall thickness measurement - NOT a pressure rating.
"NSF-PW (xxx PSI)" is a pressure rating.

Three different types of SCH40 pipe the exact same size can have 3 very different pressure ratings.

2" SCH40 DWV PVC (what you have) is made for Drain/Waste/Vent and is not made for pressure. Even worse, if it does fail, it has the potential to fail in a very violent manner, throwing lots of little pieces of PVC shrapnel around.
2" SCH40 NSF-PW PVC (what you really should use....) is made for pressure and has a rating stamped on the side of it. It's much safer. If you dropped it while it was pressurized, it could still shrapnel, but it's much less likely than with DWV pipe.
2" SCH40 DWV cellular-core ABS (perfect for combustions) is made of black ABS plastic, which is very "streachy" and "giving" compared to PVC. Smack a piece with a hammer and you'll see what I mean. If ABS fails, it "rips" open cleanly without sending shrapnel everywhere, making it a perfect choice for combustion guns - but a very bad choice for pneumatics (like yours) due to its lack of a pressure rating.
There are even more types of SCH40 pipe (CPVC, metals, etc....) but you get the idea.

Yes, if your gun fails, the most likely scenario is that the back cap would blast off. If you dropped it while it was pressurized, you'd probably be f**ked.
Keep it under 75 or 80psi, as frankrede said. I've tested ABS DWV pipe to 125psi (remotely) and it didn't fail, so odds are yours won't either - but you're playing odds. I would definitely keep the pressure relatively low. And be damn sure not to drop it while it's pressurized.

Other than the use of some DWV parts, great job. Nice design, nice craftsmanship, nice valve setup. I hope you stick around and post a few more guns.

Peace,
Pete Zaria.

PS - I <3 AMD :)
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Unread postAuthor: Intel Xeon » Sun Mar 18, 2007 2:04 pm

>_< yeah i meant Pressure rated. All the pipe and fittings have a pressure rating with nsf-pw. just the end cap is connected with dwv.

I was a forum lurker for quite a while and studied up for my first cannon :P

EDIT: I shoot crayola poster markers (very nice seal) potaotes, large grapes, cherry tomatoes, and I mold ice bullets occasionally. Pretty much anything that fits in the barrel. Oh, and I found these slightly oversized marbles at A.C Moore and they fit perfectly in sch40 3/4"

For the 2" I use potatoes (obviously)1.5" pvc 'Rockets', small onions, and once i shot like 500 steel bbs with a paper cup for wadding.
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Last edited by Intel Xeon on Sun Mar 18, 2007 2:39 pm, edited 1 time in total.

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Unread postAuthor: Pete Zaria » Sun Mar 18, 2007 2:08 pm

Damn, I just wasted 5 minutes of my life :x .

No worries.

If the only DWV part on it is the back cap and coupling - saw the f***er off. It's obviously the weakest link in your gun, so put an NSF-PW end cap on there. Or at least a pressure rated female adapter and end plug.

Good stuff :) Hope to see a few more guns from you.

BTW - what Xeon do you have, and do you overclock?

Peace,
Pete Zaria.
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Unread postAuthor: Intel Xeon » Sun Mar 18, 2007 2:43 pm

It's just my online handle. My laptop has 2.6ghz Intel Centrino dual core.
And no, I don't overclock because my chipset doesn't allow that. I could just use copper wire and physical overclock it but I don't want to :P .
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Unread postAuthor: spudthug » Sun Mar 18, 2007 6:21 pm

if im not mistaking that pipe u have has drinking water in big letter on it?? i have some of that and mine is rated to 600 psi .... if u could build a stirrup pump and get fittings and glue rated to that then holy sh*t..but its unlikely and idk if i have the same pipe as u...
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: zeigs spud » Tue Mar 20, 2007 7:51 pm

o.o very nice first! thats a nice bit o' spuding got there!
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Unread postAuthor: noname » Tue Mar 20, 2007 8:09 pm

"All the pipe and fittings have a pressure rating with nsf-pw."

Either not true or you did a shitty job cementing, no offense.
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