Coaxial Piston cannon [VIDEO]

[Brian the brain]

Oh...you might wanna rethink the title as this is a T-valved cannon..not a coax.

Coaxial means the chamber and barrel share the centerpoint.
The barrel is completely inside of the chamber.

Please don;t ever get used to this cannon..in the way that you feel safe because it has handled a certain pressure before.

It's gonna go one day or another...

i decided to build a cannon that would shoot ice/sand/ etc...

PVC gets brittle when cold.
I have personally held a cannon with ice ammo at the time it blew.
It cut my finger to the bone ( pretty much) and bruised my thigh severely.
Turned green/yellow and purple in a day or two...Before it was just black.

This was with a pressure rated cannon ( 250 psi working pressure!!) and no constructive mistakes to speak of..

DON'T EVER SHOOT ICE OUT OF A PVC CANNON!
I mean it.

All was fine until my brother pulled the pilot BV...
A very big and heavy 4" block nearly hit his head.This was the piston housing...and part of the Tee.

Only the barrel was cold, but once it blew it tore the valve apart, wich was about an inch thick of pvc where the pipe met the fitting.
It came apart like porcelin.

Excuse the all capitals..I truely believe this has the potential to mame or kill someone...

[Joelduf]

Do you think it would be possible or even helpful to wrap the pvc joints in fiberglass sheeting (with adhesive etc....) to make it stronger?

[MrCrowley]

Do you think it would be possible or even helpful to wrap the pvc joints in fiberglass sheeting (with adhesive etc....) to make it stronger?

Not worth the hassle or cost in my opinion. Much safer just building it right.

[jackssmirkingrevenge]

Do you think it would be possible or even helpful to wrap the pvc joints in fiberglass sheeting (with adhesive etc....) to make it stronger?

It's possible but infinitely more practical to just make the whole thing out of suitably rated parts.

[Joelduf]

It would cost about 20$, it seems. Much better than a new cannon. I am also a VERY patient person, and hey, I'll learn how to wrap things in fiberglass while I'm at it, right?

[jackssmirkingrevenge]

Well I suppose if you wrap it in enough layers...

[psycix]

It wont end up pretty and compact.
It would be much cleaner and safer to build a cannon out of rated parts.

If you are really patient, just save up some money and do it the right way.

[Joelduf]

More news: I have fiber-glassed the DWV thickly which no doubt has strengthened it. Also, this will prevent the cannon from shattering, instead producing a tearing action. Finally, i have set my limit at 70psi, which is very much satisfying enough for my tastes, seeing as it can launch QUITE heavy projectiles even at 20psi with great speed.
Problem Solved.

Example: It shot a baseball through 2 sheets of 1" particle board at 20psi.

[jackssmirkingrevenge]

It shot a baseball through 2 sheets of 1" particle board at 20psi.

You can't say things like that without showing us a video

[Joelduf]

Too bad i ran out of particle board to shoot, as far as i know.

[jackssmirkingrevenge]

Too bad i ran out of particle board to shoot, as far as i know.

That's the problem with a new launcher, things around the house previously considered "I'll need this some day, better store it" become "what the heck, I was going to throw it out anyway"