Tig welding exhaust (stainless)

[Mklock]

For your butt joints are most guys using filler or just fusion welding them? About to modifiy mine and do a full exhaust for the E30. I'm having a weird problem with using filler. I've not tried fusion yet though.

[Gmfwd]

Fusion is okay if the fit-up is spot on. Mine never is so I use filler.

Next time I want to try Solar Flux as a argon purge alternative.

[Mklock]

Okay, I'm still getting the feel for it, just need an auto dark helmet to perfect this. I'm running like 30-40 amps and it works okay but still making holes once in awhile lol.

[SilburE36]

I’m using 308 filler. Good fit up really helps. Seem stainless wants you to be FAST. Floor the pedal, get your puddle and it’s GO TIME. Otherwise you hang around and burn a hole.

I’m running about 50 amps on .065”, messed around with pulse a little, seems to help.


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[vollosso]

So even with perfect fitup it’s best to use a touch of filler. Lay a straight edge over your fused weld if you think otherwise.

I work small increments 3/4” at a time.

Hot and fast. With stainless heat concentrates.

After I cut every joint I take and belt sand them so they fit clean without burrs.




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[Mklock]

Thanks guys, I'll try all this. It will really help my next few projects. Didnt realize you had you haul a$$ with it so much. Yeah, I always feel uncomfortable when doing pipe too, always re positioning n crap.

[TheJuggernaut]

Thanks guys, I'll try all this. It will really help my next few projects. Didnt realize you had you haul a$$ with it so much. Yeah, I always feel uncomfortable when doing pipe too, always re positioning n crap.

Yeah, if you think about it, when you're welding around a circle, the moment you move the torch, you're already at a different angle (off on a tangent). So you really need to learn to change the torch angle with every step. Not only will it make your welds look nicer but you'll also have a much more consistent weld because the penetration and nugget size will start to taper as you start blowing heat at an angle. If your puddle starts looking more like a spearhead than a dime, stop. And use the weld appearance to judge your heat and speed. If you can't make it look silver or at worst straw, you need to move faster. And there's almost no such thing as too much argon. Ideally you want to have a fairly large gas lens with 25cfh (or more depending on the lens) chugging through, with significant pre and post flow (esp post). If your welder doesn't let you configure that, before the postflow stops, stab the pedal to initiate a new cycle. And if you're not comfortable going quicker/colder, then like others said, do a bit at a time and let it cool. Once you heatsoak things sufficiently, there's almost nothing you can do to not get a cooked grey weld which is trash.

Also do all you can to get a proper purge going, let it run long enough and don't seal things airtight, leave a small vent up high to push the air out. When you're first starting the weld, the seam is enough but as you start to close it off, you'll want the hot gas escaping elsewhere or your last quarter inch of weld will turn into an Old Faithful geyser. Solar flux does the job when other options aren't practical but you should limit it to that, it's not a substitute. The back side of the weld still won't be as good as a properly purged one.

[vollosso]

To add to the above it’s easy to mistake too little heat for needing to move faster.

If it takes too long to puddle you’re already welding at a disadvantage. The heat has already built up too much.

You should be able to weld a 3/4” bead start to finish in I don’t know <4 seconds? It should puddle very quick.

You’ll find as you go up in heat, improve torch angle and then match speed and filler your welds improve drastically.

Usually blowing a hole is from built up heat not too many amps. Food for thought.


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[vollosso]

Oh also I set the amperage like 25% high to get a quick puddle. 100% in to start the weld then I come back to 60% and get her back in to the correct heat.

If you have to reposition a lot you need to get a more stable base and become more comfortable. Weld smaller sections and really focus on angle. If you can only weld 1/4” at a time just make it a routine until filler and torch become second nature.

Sometimes I’ll weld a bit then pause let the post flow run and before it ends get back at the next section. If you’re welding hot enough and at the correct speed the metal doesn’t ever over heat. I have welded a 4” exhaust most the way around with only completing the post flow and setting the welder down maybe 3 times?

Anyway that’s my thoughts.


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[TheJuggernaut]

Yep, welding amperage and heat input are not the same thing. Heat input is the integral of the amperage. Hitting it hard and moving out adds up to much less heat than camping out forever at lower amps. I like welding very thin stuff with an initial pass using the pulser set to about 150, with 5% dc and 20-30% bg current, and WAY more amps than should be used on that thickness. Lets me fusion weld 1/16" alu and camp out as long as I want without blowing through.

[someguy2800]

If you like to take pictures of pipes with a DSLR and Instagram filters and need people on the internet to think your cool do fusion welds. If you don’t want to have to fix it after it cracks use filler.

[TheJuggernaut]

If you like to take pictures of pipes with a DSLR and Instagram filters and need people on the internet to think your cool do fusion welds. If you don’t want to have to fix it after it cracks use filler.

Depends on the application. Edit: I assumed you're replying to me but for the OP (exhaust), agreed. But for intakes and such, I have no problem with the fusion welded, unpurged Ti and shit. They could just as well use HVAC ducts.

[someguy2800]

Depends on the application. Edit: I assumed you're replying to me but for the OP (exhaust), agreed. But for intakes and such, I have no problem with the fusion welded, unpurged Ti and shit. They could just as well use HVAC ducts.

No I was replying to the OP. I use filler on almost everything, especially exhaust stuff.

Filler is a also a useful tool for controlling heat as well since that topic was being discussed as well.

[TheJuggernaut]

No I was replying to the OP. I use filler on almost everything, especially exhaust stuff.

Filler is a also a useful tool for controlling heat as well since that topic was being discussed as well.

Yeah for anything stressed, be it load or temperature swings or both, absolutely. Filler as temperature control is a great trick too, especially when fitup is questionable on thinner stuff, lay the rod in the gap and light up on it.