Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 40 users online :: 5 registered, 0 hidden and 35 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Is this dangerous?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Is this dangerous?

Unread postAuthor: ilcmuchas » Sun May 04, 2008 9:18 pm

Heres the deal, I built a spud gun today (which ive done before with sucess) I used sch 40 PVC, I have a 13 inch long 4 inch diameter combustion chamber, and a 1 1/2 inch diameter 42 inch long barrel. Now my problem is I wasnt able to find pressure rated connectors but the guy at home depot assured me that it would be ok, and after reading on some websites about people using ABS which isnt pressure rated (correct?) for spud guns and getting away with it that it was prolly ok.


The only thing Im scared of is that my connectors ad about 4 more inches to the combustion chamber, and Im making a pretty sharp change from 4 inches to 1 1/2 diameter, is this a little too risky since my reducers and bottom cap arent pressure rated? Thanks in advance
  • 0


ilcmuchas
Private
Private
 
Posts: 3
Joined: Sun May 04, 2008 9:07 pm
Reputation: 0

Unread postAuthor: jook13 » Sun May 04, 2008 10:17 pm

the problem I see if I am reading it right is the transition from pvc to abs. they dont bond together correctly.

you can buy pressure rated abs but not at home depot. it is really expensive.

I wouldnt use it if you tried to glue abs to pvc.
  • 0

I like to play blackjack. I'm not addicted to gambling, I'm addicted to sitting in a semi-circle.
User avatar
jook13
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 434
Joined: Mon Jan 21, 2008 10:39 pm
Location: Prescott Arizona
Reputation: 0

Unread postAuthor: biggsauce » Sun May 04, 2008 10:39 pm

Just use some DWV parts. Idon't think they make a 2" to 1.5" bushing, but if they do, use that and a 4" to 2" reducer.

Or, a 4" coupler, 4" to 3" bushing, and a 3" to 1.5" bushing. If they have that at the Depot...

I wouldn't try an ABS and PVC mix...
  • 0

User avatar
biggsauce
Captain
Captain
 
Posts: 338
Joined: Thu Jun 07, 2007 9:42 pm
Reputation: 0

Unread postAuthor: D_Hall » Mon May 05, 2008 12:09 am

Note that there ARE cements specifically formulated for bonding ABS to PVC.... But you have to pay attention and read the lable.
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: BigGrib » Mon May 05, 2008 2:26 am

I believe what ilcmuchas was trying to get at was not using ABS and PVC but the fact that people who build ABS cannons sometimes don't use pressure rated parts for their cannons. For me, I have always used cell core ABS, which is not pressure rated, but have used pressure rated parts. As far as reducers go, I usually advise against using bell reducers just because the formation of which is a weaker structure. The use of a bushing is more recommended just because of the structure is a lot stronger. To get from 4" to 1.5" is quite tricky. I would use a 4" to 2" bushing set in a 4" coupler glued to your chamber. Then in the 2" hole you can use a 2" to 1.5" bushing or use a 2" threaded fitting and the go to a 2" to 1.5" deal or something like that.

If you are worried about using non rated parts you should switch over to ABS because my opinion on that is that ABS is safer than PVC for combustions just because ABS rips on it's seams and PVC shatters, which I have first hand experience with. There really is no need to worry however. I have installed on my biggest combustion cannon I have a pressure gauge with a secondary peak needle that stays at the peak pressure. I have never had it peak over 100 psi so I don't think it'll be a problem.
  • 0

Yea, that's definitely going to get you at least a tazer.

<a href="http://www.youtube.com/watch?v=AkMkGOpAF4s">DONT TAZE ME BRO.. DONT TAZE ME... AHHHH</a>
facebook.com/biggrib
User avatar
BigGrib
Colonel
Colonel
 
Posts: 652
Joined: Mon Oct 01, 2007 11:43 pm
Location: TriCities, WA
Reputation: 0

Unread postAuthor: ilcmuchas » Mon May 05, 2008 4:24 am

Im not mixing ABS and PVC, I have all PVC but the couplings are not pressure rated and im wondering if that dangerous because especially since im going from a 4 inch combustion chamber to a 1.5 inch barrel.

BigGrib I used a 4 inch coupler and then the bushing style (not the cone style) reducer for 4 to 3 and 3 to 1.5 do you think thats a safe enough reduction, even with non pressure rated coupling, reducer, and end cap?
  • 0


ilcmuchas
Private
Private
 
Posts: 3
Joined: Sun May 04, 2008 9:07 pm
Reputation: 0

Unread postAuthor: TurboSuper » Mon May 05, 2008 5:18 am

As long as it's a good ol-fashioned spray-n-pray, you should be able to get away with it.
  • 0

"If at first you dont succeed, then skydiving is not for you" - Darwin Awards

TurboSuper
Brigadier General
Brigadier General
 
Posts: 986
Joined: Thu Jun 16, 2005 1:44 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: jimmy101 » Mon May 05, 2008 11:29 am

Basically all PVC combustion guns use at least one non-pressure rated fitting. Cleanout plugs are rarely pressure rated, they are strickly DWV parts.

So, I wouldn't worry about a DWV bell reducer. Most people do avoid the clearly DWV shapped parts where the OD at the socket is greater then the OD outside the socket area. Evil non-pressure rated fittings that look like it: Image
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: ilcmuchas » Tue May 13, 2008 3:09 am

ended up working great, good noise, awesome range compared to my last one. Thanks for the reassurance.
  • 0


ilcmuchas
Private
Private
 
Posts: 3
Joined: Sun May 04, 2008 9:07 pm
Reputation: 0

Unread postAuthor: FLONE » Fri May 16, 2008 3:13 pm

ilcmuchas wrote:ended up working great, good noise, awesome range compared to my last one. Thanks for the reassurance.


Perhaps not related to your original question, a 4" x 13" chamber can handle more barrel length, even with pray and spray. You'll be amazed at the distance. Good luck.
  • 0


FLONE
Private
Private
 
Posts: 18
Joined: Fri Apr 25, 2008 4:34 pm
Reputation: 0

Unread postAuthor: Boom_erang » Fri May 16, 2008 3:35 pm

True - I have a 42"x2" barrel and a 4"x8.5" chamber on my main gun, and it throws pretty far. Your chamber is oversized, which is OK if you want a loud gun, but wastes some of the power of the combustion.

-B
  • 0

User avatar
Boom_erang
Corporal
Corporal
 
Posts: 61
Joined: Fri Apr 25, 2008 2:26 pm
Reputation: 0

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'