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4 Shot Repeater Marble Rifle

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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What size ABS pipe do you think is safe to use under 150 psi?

1.5"
1
8%
2"
1
8%
4"
1
8%
No ABS is safe to use
9
75%
 
Total votes : 12
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Unread postAuthor: clemsonguy1125 » Tue Jun 29, 2010 8:48 pm

I found this, It was in some sort of Airsoft Launcher, fuel or pressure was not mentioned.
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Unread postAuthor: Technician1002 » Tue Jun 29, 2010 9:28 pm

Due to the two points of failure and not just a ripped seam, I am guessing a solid propellant was used, IE not safe for SF. This is not a pneumatic failure. This may be low pressure irrigation pipe. It does not look like cellular core.
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Unread postAuthor: jor2daje » Tue Jun 29, 2010 9:30 pm

I would still rather have that sort of failure, than sharp shards.
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Unread postAuthor: Immur4323 » Tue Jun 29, 2010 9:58 pm

I have never seen sch40 abs pipe that was not cellular core. Besides I've seen someone who has pressure tested 2" abs up to 250 psi.
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Unread postAuthor: Technician1002 » Tue Jun 29, 2010 11:37 pm

Solid Sched 40 ABS is used in industry. It is not sold in big box stores for general public home plumbing jobs.

Low density PE ( irrigation pipe ) looks a lot like the blown up sample photo. It is much thinner. I am still guessing the light interior color is the result of a propellent not permitted here. Looks like powder burns and residue.
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Unread postAuthor: spudamine » Wed Jun 30, 2010 12:09 am

pressure rated solid wall ABS is available in europe upto 200psi at 4":
http://www.pipestock.com/abs-pipe/abs-pipe-class-e-inch/?cat=1
in this case it's clearly safer to use the ABS due to the reasons mentioned by tech, it's still sold for use as water pipe though and Unfortunately it's also more expensive :(
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Unread postAuthor: clemsonguy1125 » Wed Jun 30, 2010 9:26 am

Image
This only substance in this was water.
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Unread postAuthor: Crna Legija » Wed Jun 30, 2010 10:11 am

clemsonguy1125 wrote:Image
This only substance in this was water.



are you talking like yoda

ps: im drunk and hi
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Unread postAuthor: SpudBlaster15 » Wed Jun 30, 2010 2:48 pm

Technician1002 wrote:Solid Sched 40 ABS is used in industry. It is not sold in big box stores for general public home plumbing jobs.


It is up here in Canada. Actually, it's almost impossible to find cellular core ABS here; most of the pipe sold at hardware stores is solid core.

Anyway, there's no question that ABS is the better material for gas pressure applications. I've likely built more ABS cannons than anyone on this site, and though a couple have suffered failures, not one has ever produced fragmentation. I'm currently using ABS in an application that has the pipe experiencing extreme shock loads and pressures in excess of 600PSI, and it has held up well. Used in the same manner, PVC would have turned to shrapnel on the first shot.

As for this cannon, it's borderline safe for very low pressure. With the use of cellular core pipe (Not recommended for pressure, regardless of which thermoplastic you use), and the ABS to PVC joint on the chamber, you're really pushing the line. I'd consider rebuilding the launcher using only one material.
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Unread postAuthor: clemsonguy1125 » Wed Jun 30, 2010 3:20 pm

Ok I dont want to completly hijack this thread(which seems to have alreadly happeded) but are the DWV fittings for ABS, like the reducers, Ive been convinced solid core is safe and I want to use a reducer on an ABS Advanced Combustion
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Unread postAuthor: SpudBlaster15 » Wed Jun 30, 2010 4:06 pm

ABS DWV reducers are fine for combustion cannons. I have a couple advanced combustion chambers which use reducers to transition to the barrel diameter, and they have held up well.
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Unread postAuthor: Technician1002 » Thu Jul 01, 2010 12:09 pm

This failure is from a bad glue joint. Either the coupling or pipe was contaminated, the joint put together crooked, old glue used, or not enough glue was used. The joint blew apart. Only a small portion remained bonded to the coupling. The tooth missing from the pipe is still glued in the coupling.
Image

A pipe failure looks like this.
Image

This failure is the barrel on an oxy-propane cannon. The page did not state if this was cellular core or not.

The original page is here;
http://www.sentex.net/~mwandel/cannon/my_cannon.html

This page is the one that got me to try pressure testing ABS Cellular Core in the first place. I like the failure mode over PVC.

I have not been able to find any ABS damage photos in a normal combustion, only exotic mixes. If you find a true pipe failure under normal conditions, please let me know.

Edit, the guy with the split pipe also made a marble gun. Again he used ABS for the chamber.
Image
His page on the marble gun is here;
http://www.sentex.net/~mwandel/cannon/air_gun.html
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Unread postAuthor: SpudBlaster15 » Thu Jul 01, 2010 12:56 pm

Technician1002 wrote:I have not been able to find any ABS damage photos in a normal combustion, only exotic mixes. If you find a true pipe failure under normal conditions, please let me know.


This is what an ABS pipe failure looks like on a normal combustion.

Solid core:

Image

Image

I had a picture of a fragmented cellular core ABS combustion, but I can't seem to find it at the moment.
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Unread postAuthor: Technician1002 » Thu Jul 01, 2010 3:38 pm

Do you have a photo of the label on that pipe? I have used both Cellular Core ABS and solid ABS. Solid does not have the 3 layer construction. Two layers of the pipe are showing in the photo. That pipe is Cell Core.

BRB.. I'll grab a photo of the end of a piece of Cell core for comparison.

This Oxygen enhanced Spray-N-Pray is Cellular core. All fittings are DWV. Enjoy. This video was found after I built my ABS cannon. This video is why I tested to 100 PSI this year for the first time.

[youtube]http://www.youtube.com/watch?v=WFGdK1YeuQw[/youtube]
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Attachments
ABS crack edit.jpg
Layers of Cellular core are showing
ABS crack core.jpg
ABS co-extruded pipe. It contains 2 solid layers with a bubbly layer in-between. The bubble size varies between manufactures. I have seen the stuff with very foamy size bubbles. The tiny bubble stuff has a gray appearance like the photo above shows.
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Unread postAuthor: SpudBlaster15 » Thu Jul 01, 2010 4:14 pm

That line is a burr left by the pipe cutter which was used by the hardware store to cut the pipe to length. There's no actual layer separation. It's solid core, manufactured by Ipex Inc.

Technician1002 wrote:Do you have a photo of the label on that pipe?


Not that particular section, but this one was cut from the same 12' length.

Image

And just for kicks, I do have a close up of that pipe's wall cross section.

Image
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