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what material?

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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what material?

Unread postAuthor: spudman. » Sun Oct 19, 2008 8:46 pm

my 4" abs chamber cracked.
is there anything more durable around the same cost.
i dont need the cannon to explode in my face.
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Unread postAuthor: jrrdw » Sun Oct 19, 2008 8:58 pm

4" PVC pressure rated of course.
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Unread postAuthor: jimmy101 » Mon Oct 20, 2008 10:50 am

Spudman: Please, when you post try to include enough info so people can figure out WTF you're asking about.

What kind of cannon was it? Ghetto combustion, advanced combustion, pneumatic, hybrid ...?

Jrrdw's answer is good for the first three types of guns, suicide for the fourth.
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Unread postAuthor: Demon » Mon Oct 20, 2008 12:03 pm

I dont understand why peoples makes abs cannon or coke bottle one's...
they are running after trouble!
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Unread postAuthor: Ragnarok » Mon Oct 20, 2008 12:09 pm

Demon wrote:they are running after trouble!

Not if you can find pressure rated ABS, which kicks seven shades of purple out of PVC, because it's failure characteristics are MUCH safer - it doesn't shatter into pointy shards.

ABS is the superior material to PVC, but finding it pressure rated is difficult, so the normal practise is to dissuade from using it, because a lot of muppets don't check whether it's all rated.

A lot of people still think SCH40 is a rating - it isn't, it's a measurement system.
It's like me telling you a car has a 2 litre engine when you asked the question of how much torque it outputs - sure, it gives you a rough idea, but it's far more complex than that.
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Unread postAuthor: Demon » Mon Oct 20, 2008 12:21 pm

lot of people still think SCH40 is a rating - it isn't, it's a measurement system.


I know ,but generally, the number of psi it can take is writed just beside it...
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Unread postAuthor: Ragnarok » Mon Oct 20, 2008 12:25 pm

Demon wrote:I know ,but generally, the number of psi it can take is writed just beside it...

Yeah, that's your rating. SCH40 on it's own is no guarantee.
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Unread postAuthor: ALIHISGREAT » Mon Oct 20, 2008 12:31 pm

yes but rag is saying, not all SCH40 is pressure rated and not all people know that...
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Unread postAuthor: Demon » Mon Oct 20, 2008 12:31 pm

Yeah, that's your rating. SCH40 on it's own is no guarantee.


24" PVC schedule 40 can only take 120 psi...
but 1/8 can take 800 psi!

EDIT: ALIHISGREAT again posted 10 sec before me!!!
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Unread postAuthor: Ragnarok » Mon Oct 20, 2008 12:48 pm

Demon wrote:24" PVC schedule 40 can only take 120 psi...
but 1/8 can take 800 psi!

Again, that's only RATED SCH40 - as ALIHISGREAT puts it, not all SCH40 is rated - in fact quite a lot of it isn't - and not everyone knows that, treating SCH40 as a guarantee of safety.
All it tells you is that the pipes were nominally made to certain dimensions, it doesn't guarantee quality control or flaw free parts.
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Unread postAuthor: CS » Mon Oct 20, 2008 1:26 pm

Demon, nice comparison. However remember those are pressure ratings, not actual failure pressures. Just saying that because in most situations those pipe sizes can take more then there pressure rating.

As Jimmy asked - what type of cannon was this?

Ragnarok, I've notice pressure rated ABS suggested for years on this forum, but has anyone actually used it in a cannon?

Failure characteristics are awful important in the event of a failure, but we hope that never happens. Rather I would suggest ABS because it is light weight. One of my first guns I had a little ABS chamber with an unsleeved GB barrel and that thing was light weight. But capable of sending a GB 400+ yds on a squirt of axe.

I see that 4" sch. 40 has a nominal Wt./Ft. of 2.118, but can anyone find the same measurement for 4" ABS? Would only be used for illustrative purposes, but I can't find the measurement posted anywhere.
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Unread postAuthor: Ragnarok » Mon Oct 20, 2008 2:09 pm

pimpmann22 wrote:Ragnarok, I've notice pressure rated ABS suggested for years on this forum, but has anyone actually used it in a cannon?

No idea. I know where I could get hold of it if I wanted to, but I don't have much reason to - I've grown very attached to my small bore copper.
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Unread postAuthor: DYI » Mon Oct 20, 2008 6:48 pm

I'd recommend you find yourself some solid walled ABS pipe, and avoid tapping holes into it or weakening it from its usual state in any way. If you're worried about it, just seal off the chamber and test it to 200 psi or so.

Pressure rated PVC is also fine for combustions, as long as you don't get really unlucky and find a faulty piece that managed to slip through quality control. It's probably a good idea to test ANY plastic pipe you buy to at least 1.5 times its rating if you plan to be holding it in your hands while it's pressurized with gases.

And speaking of pressure rated ABS: I found a 22" long chunk of SCHEDULE 120, 10" ABS pipe just recently. Not enough to do much with, but I'd be mucho happy if I could find a decent sized piece of it - most kickass handheld combustion ever :D (hell, it could even be a hybrid, the walls are like 3/4" thick...).
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Unread postAuthor: TurboSuper » Mon Oct 20, 2008 7:38 pm

For a basic combustion even normal DWV ABS is fine as long as it isn't cellcore. I saw a site where a guy fired it off with acetylene and it only cracked after a good while. What were you doing to the stuff?
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