Cannon blew up, rebuild time.

[ShowNoMercy]

So I dragged my air cannon out of my room today, charged it to 50 and BOOM blew out at the coupling. Shot like 3 feet of 4 inch pipe down the driveway and my supah valve into my leg. Anyway, I need to rebuild it now. So should I just make the same huge tank and keep it low pressure or shrink the chamber and operate at 100psi? The only constant here is the valve, other than that I am open to ideas.

[hi]

I had a similar experience, only my whole valve exploded. it made me not use pvc in a piston valve anymore.

I did build a smaller one that worked great, i shot it hundreds of time, then lost interest and it sat in the garage for about 2 months. then i dragged it out again. i started to fill it, but the plug in the pilot section was leaking so i tightened it with a pipe wrench and the tee cracked. im glad it cracked then and not when i shot it.

I'm a firm believer that isnt very safe to use with a piston valve. it works fine for a while, but a year or two down the road it seems to always fail. i now tend to only use metal pipe, except for on combustions. i have no problem using pvc, but i've learned to only use it on small guns. it seems to very slowly get weaker and weaker.

plus lets face it, this really isnt what its for, it just happens to be good for building spudguns out of.

i hope your "new" gun works well.

[ShowNoMercy]

I was thinking a smaller, somewhere around a foot long of 3 inch PVC, chamber and a longer smaller bore barrel, maybe 1 1/2 inch. And then maybe rig something to have an inboard HPA tank.

[psycix]

I would like to see some pictures, a properly built gun doesnt blow at 50 psi!
Why did it blow? Unproper glueing? DWV?

[ShowNoMercy]

Nope, I am guessing that the 4 inch coupling just had a weak spot in the glue. Lot of surface area to bond and all. But I tried to service my valve and I can't get the piston to come out of the tee. Any ideas?

[jackssmirkingrevenge]

I can't get the piston to come out of the tee. Any ideas?

Bigger hammer

Why not build a burst fire golfball launcher?

[F.E.A.R._Sniper]

you mean like the capabilities that the vogt's have gotten so far JSR?

i would love to have some detailed drawings and diagrams of one of those

[jackssmirkingrevenge]

I would be more inclined to scale up this design, a sort of massive BBMG with a chamber just big enough to hold 10 or so golf balls.

[ShowNoMercy]

I was thinking something along those lines. Golfball barrel, maybe 4 feet long, smaller chamber and something that I can carry easily. Def not the Vogt pattern though, my HPA is not nearly big enough.

[Mr.Sandman]

is your leg okay? ive had that happen with one of my drop piston launchers. i did not epoxy it right and the ballvalve shot at my leg and broke my shin it was so painful!

[jackssmirkingrevenge]

the ballvalve shot at my leg and broke my shin it was so painful!

As in, literally broke the bone?

[ShowNoMercy]

Well it was only like 50psi and the valve wasn't sealing right so it wasn't a huge amount of pressure. And it takes a lot to accelerate a supah valve, their kinda bulky. Still can't get the damn thing apart, What should I use as a drift? Piece of wood?

[rna_duelers]

I had a barrel explode on me in cold weather,sent pieces of PVC in every direction some about the size of a mobile phone.I wish I got some pictures of it,could you get some pictures of your blown apart cannon?I want to see how the coupler failed.

Can you pull your supah apart by any chance and get as many photo's as possible of it's inner workings?I know there a a few pictures floating around but a few more can't hurt. As for getting it out,jacks on the money,bigger hammer and maybe some KY jelly.

[ShowNoMercy]

I got it apart, used a 9oz C02 tank as a drift and a rubber mallet. As for pictures, sorry its all back together. And the coupling just shot off in one piece. Most likely a weak spot in the glue.