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My First Spud Gun

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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Unread postAuthor: nicholai » Sun Nov 26, 2006 10:28 pm

yeah a lot of people make their first pneumatic cannon using DWV parts, its not as safe as using NSF-PW fittings but it wont injure you if you take the proper precautions.

1: Dont overpressurize the cannon, a fitting popping off at low pressre is not as dangerous. Since it LOOKS like ABS (solid black pipe) not PVW (white pipe) its not rated for pressure, the benefit from ABS is that the pipe will not typically shatter like PVC so if it does get hit under high pressure it typically rips lengthwise with the pipe/fittings, where PVC will shatter.

2: Probably should fire it from a distance, make a little project box from parts at radio shack : three 9v batteries w/ clips, a pushbutton switch and a long cord, or pneumatically modify the valve and add a long hose and ball valve at the end to fire it.

3: IF you do have to drill and tap a fitting into air chamber do it over a fitting where the fitting and pipe overlap, this will give the threads more plastic to grip, also use teflon tape on the threads.

So before any of these dink heads chew you out for using DWV they or I should explain to you why NSF-PW parts are safer. NSF-DWV parts are intended for draining water from your toilet, sink, or shower and are not intended or rated to hold any pressure. NSF-PW parts have a tighter fit and have a longer depth to hold more pipe surface.

The design of the two fittings look different in apperance
NSF-PW fittings typically look streamlined, no pipe stops are visible on the outside (they are on the inside)
NSF-DWV fittings have a shorter area to grip the pipe and the pipe stops are visible from the outside and inside of the fitting.

The cannon looks overall pretty nice, you butted the two elbows pretty close together, not bad for your first cannon. Maybe throw a cool paint job on it, pimp it out with some neon lights :)
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Unread postAuthor: -Skate- » Mon Nov 27, 2006 10:03 am

Haha, Thanks loads for the help man...

We did have a problem with the elbows as we had to remove the pressure gauge before we could unscrew the solenoid. That sort of sucked.

Mostly the problem is that Home Depot only had DWV pipe. What stores sell SCH-40?
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Unread postAuthor: PVC Arsenal 17 » Mon Nov 27, 2006 2:19 pm

Lowes is pretty good for NSF-pw parts up to 2"
Some places vary, but mine always has what I need.

For the odd stuff, plumbingsupply.com and sprinkler.com are bound to have it.

Ask spudstuff aboutthe place he buys from. He said it's cheaper than anything. I think it was something like aurorasupply on eBay.
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Unread postAuthor: -Skate- » Mon Nov 27, 2006 7:13 pm

About five minutes ago I shot a couple potatoes. That was really fun considering I haven't shot potatoes before. They are my prime ammo right now.

The only downfall is I couldn't see how far it went. It just sort of disappeared into nothingness.
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Unread postAuthor: Dom » Mon Nov 27, 2006 7:41 pm

-Skate- wrote:
pyrogeek wrote:Since you have to use it, pressure test it to "X"PSI and fire it remotely. Then just fill it to like 1/2 that at the science fair. And preferrably fire it remotely their and keep people away.
For future reference though, use Sch40 or higher PVC for pneumatics. Combustion can use either Sch40 or higher, or ABS (although it's not recommended.)

I don't like how that is going from like 3inch(barrel) to 1 inch(valve) to like 2inch(barrel). Maybe you could get some 1inch ABS and make a new barrel that would screw onto the chamber, and convert it to a combustion since it would be a shame to just throw all of that away.


I'm not allowed to use it AT the science fair, I have to use it and test it FOR the science fair.

They don't want me blowing it off at the school.


Oh, and I tried it with a tomato. WORKED LIKE A CHARM.

I don't know what's so bad about it... We are staying at about 60 PSI for safety and it's doing great.


ABS can "handle" pressure.. but not REPETITIVE pressure.. read here -> first time it will work like a beauty but after a dozen shots or so, it will start to weaken to a critical point.

As for the wrapping in high quality wire and ducttape... waste of money, really. Something under pressure that needs to escape, if it breaks, it BREAKS. Nothing, except maybe a real steel wire or concrete, will stop it. It has been aborded on this forum many times, just look around.
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Unread postAuthor: SpudStuff » Mon Nov 27, 2006 7:41 pm

Yes I get my crap from several places. Like you said Aurora Supply on eBay has good prices. They relist things I believe every month. Mc Master has high prices but can ge good if you cant find specialty parts. Also, the phone book for irrigation stores. They often have good prices if you buy the entire box of fittings. That can be usefull if they are common fittings, like 4" threaded adapters.
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Unread postAuthor: SpudBlaster15 » Mon Nov 27, 2006 7:54 pm

Come on guys, stop being so paranoid. ABS pipe (as long as it is not cell core) and DWV ABS fittings are perfectly acceptable materials for use in the construction of a relatively low pressure pneumatic.

Certain individuals have repeatadly pressurized ABS pipe to in excess of 100psi without incident. Thats not to say I would want to do that on a regular basis, but it does prove that the material can easily withstand mild pressurization. Add to that the fact that if it does fail, it tears rather than shatters, and you have a more than adequate cannon building material.

With that said, great job on the cannon.
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Unread postAuthor: SpudStuff » Mon Nov 27, 2006 8:24 pm

This is freakin rediculus. A mod should lock this topic.
ABS is NOT an acceptable material for Pneumatic guns.
No questions asked. It is not pressure rated in ANY way. Being cellular core makes it even worse. Always make sure the fittings on a pneumatic say NSF-PW on them.
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Unread postAuthor: SpudBlaster15 » Mon Nov 27, 2006 8:44 pm

Most ABS is NOT cellular core, and solid wall ABS is FINE for relatively low pressure pnuematics, like I said.

It is amazing how often SpudStuff is wrong.
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Unread postAuthor: SpudStuff » Mon Nov 27, 2006 8:49 pm

Um... No, you are wrong there. Almost all ABS at stores is Cellular Core. It even says it in big bold letters. Solid Wass ABS looks the same but is extremly rare. You cannot see the bubles.
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Unread postAuthor: SpudBlaster15 » Mon Nov 27, 2006 9:18 pm

You are truley a moron. Let me clarify.

ABS cell core is not commonly found at hardware stores.
Solid wall ABS is commonly found at hardware stores.
Pressure rated solid wall ABS is extremely rare.

Do some research before making idiotic remarks.
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Unread postAuthor: SpudStuff » Mon Nov 27, 2006 9:24 pm

Can someone non retarted comment? This guy has no clue what he is talking about....
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Unread postAuthor: SpudBlaster15 » Mon Nov 27, 2006 9:29 pm

I dont know what to say to you. I have never met anyone so stubborn. Please, try to prove me wrong, I think you will be surprised...
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Unread postAuthor: -Skate- » Mon Nov 27, 2006 9:38 pm

JUST STOP ARGUING.

I GET IT. ABS SUCKS.

Seriously. I know that and I have learned that ABS is not the way to go, so you guys should stop arguing.
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Unread postAuthor: SpudStuff » Mon Nov 27, 2006 9:49 pm

Good Point! We should stop arguing until someone comments.
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