My New Cannon BIG BOY and Some Questions with Pics!

[Braddubya]

This is my first Pneumatic Cannon and I think im going to call it Big Boy





Beer can to show the scale




This is only a rough testing stage. I plan to build a better barrel/chamber sparator and to paint it.

I know the pressure chamber is much larger than it needs to be but they made me buy 5 feet of it and I think it looks cooler this way! Although it does take some time to fill...it makes up for this in the sound and kickback

I was planning to go the modified sprinkler route but when I was looking at all the fittings I needed (At the menards I went to the were no large change reducers) to go from 4" to 1" then back to 3" I could see that it was going to be cobbled and VERY restrictive. So instead I went with a 2" ball valve which actually actuates fairly quickly and with some further modification may actuate close to a sprinkler valve (Let me know if you think this could be true as I do not know the speed of a sprinkler valve and am only guessing).

I wrapped a bungee cord around one end of the valve handle and then looped it back around the gun to the other end of the handle. It snaps open very fast and when pressureized it dups the large resivour almost instantly.

Closed


Open


let me know what you think.

I also built this intending to launch water ballons but so far even when using a fabric wadding at 20psi it just shredds the balloons....any ideas?

[jrrdw]

Ok, before you hear to much I'll say it. You have some non-pressure rated parts on your cannon. As for the differance between the speed of a ball valve and sprinkler valve it's pretty much night and day in favor of the sprinkler valve.

The bell reducers have shorter sockets then couplers and flush bushings, risking pop out there. Same thing with the 90 degree fitting.

Hell of a first try!

Welcome to Spudfiles.

[Gippeto]

let me know what you think.

I think you should rename it "Bomb".

DWV isn't safe on a pneumatic. You should change out your reducers, and elbows before continuing.

All fittings should be marked NSF-PW.

My .02


Beaten again.

[sputnick]

As has been said, its a big air powered bomb. I would be VERY careful with that thing.

As for the water balloons, try lower pressures until something works, although I think it is most likely the friction of the rubber on the pipe, try wrapping the balloon in fabric in such a way that it would come off before hitting somebody

Overall, would have been an intense cannon, save for the valve, and EXTREME danger level of using non pressure rated pieces.

[DR]

There's more than a slight chance, that your cannon will rupture; There's way too much stress on the U-shaped fitting.

The duct tape should be removed from the muzzle end of the launcher, and supports should be made to run the length of the launcher.

DWV fittings are not only "non-pressure rated", but the pipe does not go in nearly as far as pressure-rated reducing components. ( The spigot ends are much shallower ).

Between tweaking the u-joint by taping the barrel to the chamber... along with the added stress of the bungie cord, the DWV Reducer (on the Chamber Side ) could very well rupture.

[ALIHISGREAT]

well... it sure is big... but the un-safeness cancels that out... as already mentioned, swap out those parts then give use some damage picz

[jonnyboy]

Well as others pointed out there's dwv on there but just cut off all the fittings except the endcap then rebuild with nsf-pw.If you can't find that big of sizes at the store you can order from here or here.

At the menards I went to the were no large change reducers) to go from 4" to 1" then back to 3"

You can use bushings instead of bell reducers and usually come in the sizes you need or if not you can just go 4-2 bushing then 2-1 bushing.

Oh and you should tap your quick connect through two layers of pvc so it would go on the side where the end cap and chamber overlap.

Hope I helped.

EDIT-can't beleive i missed the dwv pipe!

[MrCrowley]

Okay so now you have had a bunch of people telling you not to use Cellular Core and DWV you are probably wondering what pressure rated fittings look like and how to identify them, so read this:
http://www.spudfiles.com/spud_wiki/inde ... _Rated_PVC



Nice cannon otherwise.

[Velocity]

DWV does not worry me nearly as much as the fact that the pipe is cellular core. Cellular core is essentially plastic foam, and it has a VERY high chance of rupturing, ESPECIALLY when used in a pneumatic. Please, for your own safety, DO NOT FIRE THAT CANNON AGAIN. Spending more money for a safe creation is DEFINITELY going to be less than the hospital and medical care you might need when that cellular core cannon fails.

[Braddubya]

well this completely blows. there goes 60 bucks god d#$%it

this is all they have at menards and im not going to pay to ship 2 5' long tubes from some random internet site location so how am i supposed to get this stuff

[Braddubya]

on McMaster they want $25 for a 5' piece of 4" pvc! Is that a joke?

and is there any real way of getting this crap apart now that its glued?

Also what the heck am i supposed to look for?! it says schedual 40 and i thought that was it but apparently not

[john bunsenburner]

Either buy from BCarms or frm ebay, or use metal, but for your own safety please dnt use that cannon, it could end up in some serious damage.

P.S. Where i live they is one size of pvc, its not pressure rated and costs about 40$ for 3 feet...

[MrCrowley]

You should be thankful you have such low prices in America. I'd pay about $170USD for 6' of 4" PVC. The price doesn't seem that extreme to me, but you probably can get it cheaper at a Home Depot or Lowe's.

BTW, McMaster isn't some random internet site, they are professionals and you wont get forked about by them. They're very reliable. I'm sure they can ship in 5' lengths as well.

I don't see why you would want to take it apart in the first place, the only fitting/pipe that might be pressure rated is the ball valve, and there's no way to save it now.

BTW, edit your posts instead of double posting. We don't allow double posting on Spudfiles, if you have something more to say, edit your last post or wait until someone else posts.

[MaxuS the 2nd]

Schedule-40 is just a wall thickness. Bugger all to do with pressure ratings.

[Braddubya]

how can i tell if its pressure rated? Is there a code on it of some type or will they all just say the pressure?