Cell Core PVC

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
stevethecat
Private
Private
Posts: 3
Joined: Tue Jan 02, 2007 10:11 am

Wed Jan 03, 2007 9:57 pm

Hello, I built my first spud gun yesterday. Its a simple combustion gun, and i was pretty proud of it.

I was going to test it today after work, but when reading the wiki on this sight i saw that you should never use cell core pvc because it cant take any pressure.

I got to thinking about my gun and, as luck would have it, about 3 inches worth of my 13 inch chamber is 4 inch cell core pvc.

I intended to rebuild the gun, but when i went back to lowes today and, everything bigger than 2 inch pvc is either very thin wall, or its cell core.

So i have 2 questions for you guys.

1. Where can i find sch-40 pvc over 2 inches.

and

2. Would it still be ok to use the gun i made even with the cell core portion? Arent combustion guns pretty low pressure compared to everything else, or do they still make to much pressure for cell core?




PS: I didnt let this little setback deter me. Since i couldnt find the parts i wanted, im decided to make an over/under style combustion gun with 2 inch pipe as the chamber and 1.5 inch pipe as the barrel.

Its going to have about a 40 inch barrel and a 34 inch chamber, that should give the chamber about 106 cubic inches of volume and a 1.5:1 chamber to barrel ratio.

Its not the 150 that the other gun had in the chamber, but at least theres less chance of exploding. (and thats always a nice point)
pyromanic13
Corporal 5
Corporal 5
Posts: 913
Joined: Wed Oct 19, 2005 7:54 pm

Wed Jan 03, 2007 10:14 pm

cell core... I'd go for it with a combustion...
Movie dialogue: "The good die first."
Tom: "But most of us are morally ambiguous, which explains our random dying
patterns."
User avatar
Canuckicks
Private 2
Private 2
Posts: 33
Joined: Sun Dec 24, 2006 8:24 pm

Wed Jan 03, 2007 10:26 pm

Cell core should be fine for a combustion gun but just for peace of mind i would cover your gun in some duct tape or another adhesive so that if it does fail there is some protection from the flying PVC shards (this is known not to be very effective but it is still worth it) your new gun sounds good but the small diameter chamber will make it hard to fill and ignite properly
User avatar
jjjd
Specialist
Specialist
Posts: 117
Joined: Wed Nov 29, 2006 12:39 pm

Thu Jan 04, 2007 12:04 am

duck tape Does Nothing! people always say something like that, just wrap it. it will not help at all, and yeah i would do it with what u got, and if u are looking for the sch 40 pvc order from www.Mcmaster.com(only if u live in the states,im in canada and they dont ship here)
User avatar
MrCrowley
Moderator
Moderator
Posts: 10078
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Been thanked: 3 times

Thu Jan 04, 2007 12:11 am

or you could put an old jean leg over the cell core partion,it wont do alot but it could save your eye or you getting a flesh wound if it blows.
stevethecat
Private
Private
Posts: 3
Joined: Tue Jan 02, 2007 10:11 am

Thu Jan 04, 2007 7:20 am

Thanks for the help guys.

Ill mount the igniter on the gun today after work and hopefully get some pictures up.
User avatar
frankrede
Sergeant Major 2
Sergeant Major 2
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Has thanked: 1 time
Been thanked: 1 time

Thu Jan 04, 2007 6:23 pm

cell core if perfect for combustiuons dont listen to them they dont know wat they are talking about.
Current project: Afghanistan deployment
User avatar
Pete Zaria
Corporal 5
Corporal 5
Posts: 954
Joined: Fri Mar 31, 2006 6:04 pm
Location: Near Seattle, WA

Thu Jan 04, 2007 6:27 pm

We need to know if it's cell core PVC or cell core ABS.

Cellular core PVC will shrapnel if it explodes, and since it's cell core, it's more likely to blow anyway.

Cellular core ABS isn't a problem - I've personally tested it to over 125psi without failure. When it's made to fail (at over 150psi in my case) it doesn't grenade and shrapnel at all, it rips open clean lengthwise down the pipe.

Peace,
Pete Zaria.
User avatar
frankrede
Sergeant Major 2
Sergeant Major 2
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Has thanked: 1 time
Been thanked: 1 time

Thu Jan 04, 2007 11:32 pm

Its cell core pvc, hence the writing and topic name.
Current project: Afghanistan deployment
User avatar
mark.f
Sergeant Major 4
Sergeant Major 4
Eritrea
Posts: 3638
Joined: Sat May 06, 2006 11:18 am
Location: The Big Steezy
Has thanked: 58 times
Been thanked: 60 times
Contact:

Donating Members

Fri Jan 05, 2007 6:45 am

Just do yourself a favor and get some solid core pipe. May cost a little more, but at least you'll feel safe shooting in chilly weather, (I've used my solid-walled PVC guns below 40 degrees fahrenheit). Also, it's too much of a structural hazard! The pressure might not break it, but stress from the weight of the barrel or slight impacts could spell the end of this gun.
stevethecat
Private
Private
Posts: 3
Joined: Tue Jan 02, 2007 10:11 am

Fri Jan 05, 2007 8:32 am

Ok, i put the ignition system on and shot the gun once last night (would have been more but its to loud for that time of night).

Thankfully nothing exploded.

Cold weather really isnt a problem, even this time of year. I live in midwest GA and besides the occasional odd cold snap days, it doesnt really get all that cold. There have only been about 5 days so far this year that i couldnt wear a t-shirt outside.
User avatar
benstern
Corporal 5
Corporal 5
Posts: 908
Joined: Wed Sep 21, 2005 8:24 pm

Donating Members

Fri Jan 05, 2007 2:19 pm

Go to the local ace hardware to find pressure rated pipe and fittings up to 4"
Post Reply