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 38 users online :: 4 registered, 0 hidden and 34 guests


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

Registered users: Bing [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

Steel pipe questions

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
Sponsored 
  • Author
    Message

Unread postAuthor: ramses » Thu Oct 15, 2009 6:53 am

-_- wrote:some people make epoxy plugs in side male end caps
and have there spark gap(or spark plugs from cars)there.


You will need two wrenches, or a wrench and a vice large enough (I had to go to my dad's shop to put my 2" together.

Sparkplugs JB welded into bushings make nice ignition systems, the downside is that the chamber can sometimes be "hot", giving you a shock instead of firing the gun. They are made to withstand hundreds of shots from a full auto, ~12x hybrid.
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: kjjohn » Thu Oct 15, 2009 7:08 pm

found most of the parts I'll need on McMaster, but the pressure ratings are a little confusing. I already asked about the large pipes and got a good answer, but after looking at the small fittings, I found that most aluminum and steel fittings (elbows, reducer, etc.) are only rated for 150psi. Considering that this cannon will produce between 300 and 500 psi, will it be safe to use these fittings?
  • 0

User avatar
kjjohn
1st Lieutenant
1st Lieutenant
 
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Reputation: 0

Unread postAuthor: Reactor4 » Thu Oct 15, 2009 7:32 pm

yes, the pressure produced from combustion inside the cannon will be at high levels for milli seconds, the pipe fittings can also withstand more than they are rated for, and the rating is based on a constant pressure at specific temperatures. You'll be fine. :D
  • 0

User avatar
Reactor4
Specialist
Specialist
 
Posts: 58
Joined: Fri Oct 02, 2009 9:56 pm
Reputation: 0

Unread postAuthor: kjjohn » Thu Oct 15, 2009 7:54 pm

thanks for all the help, hopefully you'll see my hybrid in the showcase within the next few months.

edit: Actually, I have one more question. :) I am planning on having a compressed air tank on board the hybrid so that I don't have to go to the compressor for each shot, but I can't find any air tanks that are cheap enough or light enough. I was thinking I could maybe just use steel pipe, but it would have to be able to withstand up to 400psi continuously for long periods of time (until it ran out of gas). Would it be safe to do this, or would the high pressures cause it to fail?
  • 0

Last edited by kjjohn on Thu Oct 15, 2009 8:17 pm, edited 1 time in total.
User avatar
kjjohn
1st Lieutenant
1st Lieutenant
 
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Reputation: 0

Unread postAuthor: D_Hall » Thu Oct 15, 2009 8:10 pm

Moonbogg wrote:2" sch40 aluminum, assuming it is the standard 6061-T6 will easily handle 500psi.


However, be advised that welding 6061-T6 will make it MUCH weaker. So if you're using threaded fittings, fine, but if you're welding do NOT use the rated pressure (if there is one).
  • 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: Reactor4 » Thu Oct 15, 2009 8:55 pm

it should be fine to use steel pipe as an onboard air tank. you might want to look at the sch.80 steel pipe on McMaster, as it will provide a safe rating for 400 psi, along with the use of corresponding fittings. (on mcmaster, when you go to the fittings page for steel, you can select sch. 80 when you click on the type of fitting you want. The fittings' catalog page will also tell you the rating, as you probably know.) Glad to help! :D
  • 0

User avatar
Reactor4
Specialist
Specialist
 
Posts: 58
Joined: Fri Oct 02, 2009 9:56 pm
Reputation: 0

Unread postAuthor: kjjohn » Sat Oct 17, 2009 5:40 pm

D_Hall wrote:However, be advised that welding 6061-T6 will make it MUCH weaker. So if you're using threaded fittings, fine, but if you're welding do NOT use the rated pressure (if there is one).


Brazing aluminum will not have the same effect, will it?
  • 0

User avatar
kjjohn
1st Lieutenant
1st Lieutenant
 
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: kjjohn » Wed Nov 04, 2009 5:39 pm

Will 3" schedule 40 steel pipe be able to withstand a burst of 900-1200 psi? (not continuosly, just the combustion pressure)
  • 0

User avatar
kjjohn
1st Lieutenant
1st Lieutenant
 
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Reputation: 0

Unread postAuthor: D_Hall » Wed Nov 04, 2009 6:50 pm

kjjohn wrote:Brazing aluminum will not have the same effect, will it?

While I've not done the research, I would be *shocked* to learn that it doesn't have the same effect. In the event that sentence was unclear due to the use of negatives I'll restate: Yes, I believe brazing aluminum will have the same weakening affect on T6 aluminum that welding has (but can't swear to it since it's not a problem I've expressly studied).


edit: Did some googling. My google-fu is weak and I didn't find exactly what I was looking for, but I did find that welding 6061-T6 reduces it's strength by about 25-30%.
  • 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: kjjohn » Wed Nov 11, 2009 7:09 pm

I just discovered that I can buy aluminum pipe for about 1/4 the price on Speedymetals than I can on McMaster, but it isn't threaded. How do I put it together since aluminum cant be welded or brazed? Could I possibly use a metal filled epoxy?
  • 0

User avatar
kjjohn
1st Lieutenant
1st Lieutenant
 
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Reputation: 0

Unread postAuthor: xequa » Fri Feb 12, 2010 12:53 pm

Any ideas on where to get 3" steel pipe? I'd like to make a full steel cannon so it'll withstand the pressure of launching a 2.5' long slug of drywall cement. But with that kind of weight, I'd like the whole gun to be made of steel so that safety is well in hand. Any ideas?
  • 0


xequa
Private
Private
 
Posts: 23
Joined: Fri Nov 16, 2007 10:12 am
Reputation: 0

Unread postAuthor: ramses » Fri Feb 12, 2010 1:25 pm

mcmaster...

If it's pneumatic, you can probably get by with good barrel braces and some kind of "stock" to distribute the recoil from the back of the cannon to whatever.
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: metalmeltr » Fri Feb 12, 2010 3:36 pm

kjjohn wrote:I just discovered that I can buy aluminum pipe for about 1/4 the price on Speedymetals than I can on McMaster, but it isn't threaded. How do I put it together since aluminum cant be welded or brazed? Could I possibly use a metal filled epoxy?

Aluminum can be welded. All you need is a MIG or TIG welder. If you have more welding quetions go to the forum at www.millerwelds.com
  • 0


metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: ramses » Fri Feb 12, 2010 4:33 pm

welding and probably brazing reduces strength 30%.

You could try to find or make compression fittings, or solder it.

or epoxy, especially if this is a pneumatic.
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: Moonbogg » Fri Feb 12, 2010 8:28 pm

If you aren't welding, use bolted connections OF COURSE. Please do not glue your hybrid together and expect to live.
  • 0

User avatar
Moonbogg
Major General
Major General
 
Posts: 1375
Joined: Mon Oct 13, 2008 10:20 pm
Location: whittier, CA USA
Reputation: 0

PreviousNext

Return to Construction Materials/Ammo Discussion

Who is online

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

Reputation System ©'