pic: Team 540 Air Cannon

[Rob2713g]

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[Otaku]

As I said in the other thread,

PVC = horribly unsafe. I would make it out of ABS if I were you.

[Qbranch]

I tried to cut the plastic out for use as a pressure vessel and just use it as a barrel... then use 1~2 of the craftsman pressure tanks instead, and manifold them together (if i use two) to increase the flow rate (they have a single 1/2" port)

However, i keep having trouble figuring out what kind of threads go with what.. NPT, NPTF, BSPT, I seem to go in circles and get confused.

Anybody out there good with pipe threads?

-q

[Herodotus]

This may have been addressed in another thread but couldn't you make the PVC safer by wrapping it in duct tape?Wouldn't give it more strength, but I would think it would prevent sharp shards of PVC from being sprayed everywhere in the case of rupture.

In any case, it's looking pretty good. We worked on an air cannon last year but haven't done any more with it. This year we're doing something else with the pneumatics.

[Protronie]

Originally Posted by Qbranch

I tried to cut the plastic out for use as a pressure vessel and just use it as a barrel... then use 1~2 of the craftsman pressure tanks instead, and manifold them together (if i use two) to increase the flow rate (they have a single 1/2" port)

However, i keep having trouble figuring out what kind of threads go with what.. NPT, NPTF, BSPT, I seem to go in circles and get confused.

Anybody out there good with pipe threads?

-q

Tanks usually (99.9%) come with NPT threads so NPT or NPTF fittings will work with them. FYI NPT & NPTF threads are interchangeable with use of PTFE tape.



Finding fittings that use BSPT threads in the US might be a problem.

Finally my apprenticeship years as a pipe fitter/ boiler operator come in handy here

[Leav]

Originally Posted by Otaku

As I said in the other thread,

PVC = horribly unsafe. I would make it out of ABS if I were you.

Though PVC creates shards, and ABS only ruptures (and does not explode), It has been thoroughly researched by people at the the SpudTech forums (now closed) and now the people at Spudfiles, and Sch 40 and Sch 80 PVC are a tried and tested way to create Pneumatic spudguns.

Duct tape tears easily and in our tests it was unable to stop an exploding PVC tank (we went to twice the rated maximum pressure, and slammed the tank with a remote activated 10lbs sledgehammer). In fact the shards we so quick when they exited through the duct tape that they also went through the plywood box the canon was in.


in a second test the gun was wrapped in an old pair of heavy duty Jeans. (the leg part), and when it exploded the jeans held the shrapnel.



At any case pneumatic spudguns are VERY DANGEROUS!
they can be fun but they should be treated even more carefully than a real gun, because a gun can only fire in a single direction, a spudgun might explode if handled the wrong way!!!

be careful!!!!!!

-Leav