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Explosive pvc failure

Unread postPosted: Sun Jul 12, 2009 10:59 pm
Author: skyjive
So I just finished the soldering and threading and my shiny new copper marble MG was complete. The only thing lacking was a copper fitting to cap off the magazine, which pressurizes when the gun fires. Since it was 11 PM and all hardware stores (even Home Depot!) were closed, I screwed on the only thing at hand, a pvc endcap with a schraeder glued in the middle, hooked up my CO2 tank, and tested the gun. The first 3 shots were an unqualified success. The on the fourth shot, instead of a marble hitting the backstop downrange, there was a crack and fragments of pvc went flying past my head, one hitting me in the face, another in the shoulder (no harm done, thankfully). Here is what rapid pulses of 120 psi CO2 does to pvc weakened with a hole drilled for a schraeder:

Image

This is the first time any gun component has failed under pressure in my experience, and I just thought I'd share it. Tomorrow I will cap off the magazine properly with copper and do a write-up for the MMG if it still works.

Unread postPosted: Sun Jul 12, 2009 11:41 pm
Author: theBOOM
Hm did the PVC damage you at all???

Any blood :?:

Unread postPosted: Sun Jul 12, 2009 11:51 pm
Author: THUNDERLORD
:lol: Pic looks like a m@sturb#t!on toy... size extra small. :lol:

I liked part where the PVC flew past your head...

Next time maybe no pressure magazine equipped with PVC end cap???
I remember one PVC failure vid with a cardboard box backstop and everyone was skeered but when you look close none of the PVC penetrated the carboard.

Congratulations on the failure...Good thing you didn't shoot your eye out.
Not even a good Darwin machine.
I bet your launcher is a piece of sh!t!!! :P :lol:

Unread postPosted: Mon Jul 13, 2009 1:02 am
Author: jackssmirkingrevenge
THUNDERLORD wrote::lol: Pic looks like a m@sturb#t!on toy... size extra small. :lol:


It does?! Looks pretty hardcore to me, what with the protruding shards of PVC and whatnot :shock:

skyjive, if you have the resources, how about some testing? ;)

Re: Explosive pvc failure

Unread postPosted: Mon Jul 13, 2009 1:58 pm
Author: Technician1002
skyjive wrote:So I just finished the soldering and threading and my shiny new copper marble MG was complete. The only thing lacking was a copper fitting to cap off the magazine, which pressurizes when the gun fires. Since it was 11 PM and all hardware stores (even Home Depot!) were closed, I screwed on the only thing at hand, a pvc endcap with a schraeder glued in the middle, hooked up my CO2 tank, and tested the gun. The first 3 shots were an unqualified success. The on the fourth shot, instead of a marble hitting the backstop downrange, there was a crack and fragments of pvc went flying past my head, one hitting me in the face, another in the shoulder (no harm done, thankfully). Here is what rapid pulses of 120 psi CO2 does to pvc weakened with a hole drilled for a schraeder:

Image

This is the first time any gun component has failed under pressure in my experience, and I just thought I'd share it. Tomorrow I will cap off the magazine properly with copper and do a write-up for the MMG if it still works.


It looks like the magazine launched into the loading cap. Maybe a bumper between a tube of projectiles and the target is in order. :D This is most likely a projectile damage, not a pressure damage.

Re: Explosive pvc failure

Unread postPosted: Mon Jul 13, 2009 2:31 pm
Author: jackssmirkingrevenge
Technician1002 wrote:This is most likely a projectile damage, not a pressure damage.


Agreed, happened to me with Tee magazines - as the mag empties, it effectively becomes a vertical barrel :?

Unread postPosted: Mon Jul 13, 2009 3:07 pm
Author: skyjive
Ah of course, that makes sense. But now with a copper endcap I don't think any marbles will make much impression (though I'm definitely keeping my face away from the mag now).

Unread postPosted: Mon Jul 13, 2009 3:09 pm
Author: jackssmirkingrevenge
You'll be surprised, I'd definitely put some sort of rubber/spring buffer.

Unread postPosted: Wed Jul 15, 2009 3:35 pm
Author: LCTChamp
PVC, cold, and high pressures don't work well together. I'm just glad you didn't get hurt.