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First Pneumatic, Q's

Posted: Wed Aug 22, 2007 5:48 pm
by CannonCreator
My little brother (6 years old) Has enjoyed watching me make cannons, and shoot them. He just asked me in the morning when I woke up if I can give him money to make a cannon. He had very good designs, so I took him to home depot, And we got everything. He just put it all together (under my supervision) and right now the cement is drying.

I have Never made a Pneumatic Cannon before, and after looking at the threads, Im begining to wonder, If the ammo is going to be able to get anywere(from my cannon knowledge, I thought it would work).

Specs:

34 1/2" long, 2" diameter chamber

30 1/2" long, 3/4" diamater barrel


He is planning to shoot darts, and some taped up bolts that perfectly fit the 3/4" barrel. Anyway Just tell me what you guys think. I haven't Made a Pneumatic before, nore even shot one. So How do you guys think it will do?

Posted: Wed Aug 22, 2007 5:51 pm
by Pete Zaria
1) What kind of pipe are you using? PVC, ABS? Is it pressure rated? Do you know how to tell?

Most hardware stores only carry DWV pipe in my experience which is only safe upto about 75psi. The pipe needs to say "NSF-PW" and a pressure rating ( xxx PSI ) to be used above that.

2) What kind of valve are you using? With a ball valve, don't expect anything real exciting. A sprinkler valve, especially a 1" modified one, will be pretty impressive.

Peace,
Pete Zaria.

Posted: Wed Aug 22, 2007 5:52 pm
by hi
ohh yea, even with a ball valve its gonna shoot pretty well. ive made ball valve pneumatics about half that size and they are still very powerful.

Posted: Wed Aug 22, 2007 5:53 pm
by scatdawg
your chamber/barrel volume ratio should be fine. what are you using for the valve?

Posted: Wed Aug 22, 2007 5:57 pm
by CannonCreator
Ya it has a ball valve, and it is 280psi pressure rated PVC (im not that stuid to use ABS with a pneumatic)

Posted: Wed Aug 22, 2007 5:58 pm
by DYI
If you're wondering about its C:B ratio, it should be fine. It should preferably have a MUCH longer barrel if you want high performance though.

What you can expect all depends on the pressure you use, and what kind of valve it has.

EDIT: just saw above post, deleted part about DWV.

Posted: Wed Aug 22, 2007 6:00 pm
by scatdawg
should work just fine. make sure you let the cement set up several hours just to be completely safe. i also always shoot new cannons at low pressures and gradually work my way up the pressure scales. remember safety first. good luck

Posted: Wed Aug 22, 2007 6:01 pm
by MisterSteve124
What about your fittings? Are they pressure rated? Other than that it looks fine.

Posted: Wed Aug 22, 2007 6:05 pm
by CannonCreator
Ya every pipe/fitting on the gun is PVC, sp ya everything including the fittings is pressure rated. My brother is very anxious right now, so were going to go make some more ammo. Thanks guys!

Posted: Wed Aug 22, 2007 6:14 pm
by DYI
Just make sure to wait at least 24 hours after applying the solvent cement to fire it. That stuff dries quickly, but takes a long time to cure.

Posted: Wed Aug 22, 2007 6:38 pm
by Redcoat
Darts and bolts should work fine.Just make sure with the darts that you put a stopper behind it so that the full amount of pressure is exerted upon the dart.
I.e. Cotton Wool.

Happy SPuddin'

Posted: Wed Aug 22, 2007 6:56 pm
by CannonCreator
K thanks guys! and all the ammo we have ready right now is perfect diameter, so theres no lost pressure. Thanks again!

Posted: Wed Aug 22, 2007 7:39 pm
by potatoflinger
Do the fittings say nsf-pw? (That's good)

Posted: Wed Aug 22, 2007 10:47 pm
by MrCrowley
CannonCreator wrote:Ya every pipe/fitting on the gun is PVC, sp ya everything including the fittings is pressure rated. My brother is very anxious right now, so were going to go make some more ammo. Thanks guys!
Just because its PVC,doesn;t mean its pressure rated. Please post the pipe specs, e.g NFS-PW 280PSI @73F
Make sure all the fittings are rated also.

Did you use primer? You failed to mention it so im a bit worried you didn't. If you haven't used primer I recommend not using the cannon, especially when a 6year old kid is involved. Personally I think he's too young, but its up to you and your family.

I also recommend you take the solvent welding course(don't ask, just search). Letting your 6yo brother assemble it, probably isn't the best thing.

Side note: ABS is fine to use in a pneumatic, if it is pressure rated. I know alot of amature spudgun websites out there, say not to use it at all, but they have no idea what they're talking about.
Pressure Rated ABS is one of the best spudgun materials out there if you can find it and afford it.

Posted: Wed Aug 22, 2007 10:52 pm
by CannonCreator
MrCrowley wrote:
CannonCreator wrote:Ya every pipe/fitting on the gun is PVC, sp ya everything including the fittings is pressure rated. My brother is very anxious right now, so were going to go make some more ammo. Thanks guys!
Just because its PVC,doesn;t mean its pressure rated. Please post the pipe specs, e.g NFS-PW 280PSI @73F
Make sure all the fittings are rated also.

Did you use primer? You failed to mention it so im a bit worried you didn't. If you haven't used primer I recommend not using the cannon, especially when a 6year old kid is involved. Personally I think he's too young, but its up to you and your family.

Yes I know how to to put PVC together, I used PRIMER and CEMENT, and my borther isn't allowed to use it by himself only with me or my dad. And its sad how much he knows about guns, so we decided to let him vent some anxioty of making cannons off.

I just checked, the fittings are 150psi pressure rated PVC.