SpudFiles

This is the air cannon that I built as a marshmallow gun. Origonaly it had a PVC chamber, but it broke so I replaced it with metal. Eventuallty I will replace the valve with a sprinkler valve. The ball valve on the barrel serves as a breach loader.

1/2 bore
200psi and under operating pressure
I make ammo by taking a hook cutting off the bent end sharpening the cut off end and casting lead on the threaded end. I use 1/2" copper as the mold for the lead.

ummm..... you broke a pvc chamber??

Did you use DWV fittings? (non pressure rated)
Did you use the proper glue?

PVC is very strong, and would not fail if you used pressure rated fittings and assembled it correct-ally.

Good job. Is this your first pneumatic? What is the target you were shooting at? It looks like a panal from a truck but I can't tell...

jhalek90 wrote:ummm..... you broke a pvc chamber??

Did you use DWV fittings? (non pressure rated)
Did you use the proper glue?

PVC is very strong, and would not fail if you used pressure rated fittings and assembled it correct-ally.

Pffft, PVC aint strong. actually, it's crap.
http://www.spudfiles.com/forums/viewtop ... tml#282339

take that back PVC is bestly!

also im not too sure what ot say about you barrel, im not familiar with the pipe type so i coundt tell you if it was too much pressure

The PVC chamber consisted of an about 6" piece of 1.5" pvc and two endcaps. I drilled a hole in either end and tapped it to 1/4" npt, one end was screwed on to the valve and on the other end i screwed a pipe nipple and a ball valve with a quick disconect fitting. When the gun was pressurized (200psi) i accidentally dropped it and the pipe exploded from the valve being ripped out of the end. This is my second pnuematic, no pictures exist of the first.
The target is a fender fron a car. I have no idea what kind of car.

The drop probably cracked it and the pressure did the rest, something similiar happened to me

My guess was that you messed up wile tapping the pvc. Also may I ask why you were using 1.5 pvc at 200 psi?

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SpudBlaster15 wrote:I have a couple NSF-pw PVC launchers, and honestly, they're a little frightening to hold and fire. I'm always expecting them to explode into a hail of shrapnel.

Yeah that's exactly what I am scared of... but it is rather rare. Unless you're stupid and put it up to like 200 psi.

seriously, Ive never taken one past 80 and usually operate at 60

I used the pvc at 200psi because the pressure rating was something in the range of 355psi. That is more that 150psi over my maximum operating pressure. I was going to put a meal chamber on the gun anyway so I could use higher pressure, but the broken chamber just accelerated the process. When the chamber did explode the piece that hit my leg did nothing more than leave a red mark.

I intend to make another all metal gun soon to use at 600psi. The valve will be either QEV or a power washer handle. Can someone who has GGDT run a simulation to compare a 3/8 power washer handle to a 3/8 QEV, I can't download GGDT. The chamber would be 3/4" by 6" and the barrel would be 1/2" by 36". I dont need insane performance and either way I have to buy the power washer handle eiher for the main valve or for the pilot, I want to see if the money for the QEV would be worth the extra perormance.

You don't select valves like that when modeling a gun in GGDT. It would be hard to model the two and tell the differences, at least for me.

metalmeltr wrote:I used the pvc at 200psi because the pressure rating was something in the range of 355psi.

Some PVC is rated as high as 1000 psi Ive heard but since its brittle and temperature affects it, its never a good idea to take it above 120 psi ands best to stay at 100 or lower