your tubing welds (pics)

[havik180]

Anyone have pics of projects or practice welds they did involving tubing ? Also for those of you with experience with tubing what tips can you give for mild steel tubing ? I seem to have trouble with overheating the metal and blowing holes in the metal. Is the trick to stop/start a few times or what ?

[Revlimit]

Havik...what's the tubing's wall thickness? Are your joints tight or poorly fit? Are you using tig, mig, or stick? Rev.

[arcdawg]

http://millermotorsports.com/mboard...ttachmentid=453[/url]

chrome moly broke at 5800psi

dawg

[havik180]

Havik...what's the tubing's wall thickness? Are your joints tight or poorly fit? Are you using tig, mig, or stick? Rev.

It was 1" tubing with about 1/16" wall thickness (mild steel), the joints weren't water tight but there wasn't a big gap either (best I could do with a bench grinder)and I was using my MIG ,c-25 w/ .030"

[Blondie_486]

Havik,

You might want to try dropping to .023 wire and turning your heat down. Then run a quick root pass then go back and put a good weld down.

What is this going to be used on?

My personal preference for welding tube joints is TIG. But then you have to use what you have available.

[eric75]

Why the root pass?

[Revlimit]

Havik, I assume you don't have tig access since that would be my choice. 1/16 wall is pretty thin, and like Blondie said, I would try a small wire. You can still get good penetration at a lower Amp setting. With the thin stuff like that you can try the start/stop method or even spot...spot...spot all the way around. It just depends upon your application. You wouldn't want to do that on a race chassis for example. Rev.

[stinkinlincoln]

where I work we use MM251s w/.035 wire and trimix gas, pretty hot for 1/16 wall but I have welded several exhuast pipes with this setup. I turn it down as low as the machine goes and travel downhill fast!! . I have also found that if you turn the wire up some you can putdown a series of hot tacks moving downhill, I have butt welded exhaust tube this way it works good. Of course I wouldn't do this on structural stuff. Downhill always minimizes penetration, it just may be prone to crack. Oh yeah, my welds don't leak either. They actually look way better than most of the crap I've seen done in muffler shops.

[Blondie_486]

Eric 75,

Actually that's a good question.

The purpose of the root pass would be to fill in the gaps as he stated he did the best he could with a bench grinder and there's bound to be a few. Additionally it provides a bed for the second pass so it won't fall through when you turn up the heat for penetration and to wet it into both surfaces being welded.

It's something I learned long ago when I did X-Ray welding. Everything had to be beveled and have a gap in it and we'd start with a 3/32 rod and burn in a root pass then turn the heat up and run 1/8 rods to fill up and if the material was thick enough graduated to 5/32 rods. Some of the other welders used to use 1/4 rod but I held off at 5/32

Blondie

[havik180]

So would it be better to "push" or "pull" the bead when welding say a roll cage or a tubular chassis ?

[Blondie_486]

Havik,

Most of the welds will be out of position anyway and most people run MIG downhill so you're probably pulling most of the bead anyway so I don't see what it'd hurt to pull the whole bead. Start at the top center of the joint and run down to the center bottom on one side then the other side the same way. I'm a little backwards myself and start at the bottom and work to the top, but this is a personal preference thing, it's what I'm comfortable with. Although I am trying to master running MIG downhill

Also my preferred way to weld roll cages and tubular chassis is TIG but then you have to use what you have on hand. Presently though I don't even have access to TIG, but hope that will change in the future. Now in my younger days I have built quite a few dune buggies and stick welded them all with 7018. MIG is an acceptable method of welding roll cages and tubular chassis and will pass NHRA inspections on mild steel applications. I guess I'm personally not as comfortable with MIG welding as I am other welding methods.

Well good luck with your project and hopefully it'll turn out great.

Blondie

P.S. If you're having problems with getting the bead to wet in using the C-25 gas you may want to try 95-5 (95% Argon 5% Co2), that's what we're using at work and it wets in nice compared to the straight Co2 we were using at the shop I worked at prevoiusly.