[Chips O'Toole]

Do I need a helium mix for welding stainless, or is my usual argon/CO2 okay? Seems like I get a lot of spatter.

[Coldman]

Has to be pure argon for stainless


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[Chips O'Toole]

It sounds like I'm going to need a whole bunch of tanks if I want to use both MIG and TIG on ferrous metals, stainless, and aluminum.

[cj737]

It sounds like I'm going to need a whole bunch of tanks if I want to use both MIG and TIG on ferrous metals, stainless, and aluminum.

You can do it all with 2: 100% Argon to TIG steel, aluminum, etc. 75%/25% MIG for steel, 100% Argon to MIG aluminum.

Helium is not required, but helpful with Aluminum TIG.

I use 3: 100% Argon, 100% Helium and a 75/25 for steel MIG. I use a Y connector on the TIG to allow any ratio of He with the Ar.

[Chips O'Toole]

That is really helpful. Thank you.

[Otto Nobedder]

MIG welding stainless steel can be done with 75/25 Ar/CO2 as with mild steel, but you've already noticed the spatter, and the color is dark. 98/2 Ar/O2 makes better welds. I personally prefer tri-mix, 90/7.5/2.5 He/Ar/CO2, but the customers spec it, and pay for it. (Also, our customers make it, so they're basing the choice on an engineering decision.)

Steve S

[Chips O'Toole]

I found a dude on Craigslist selling 125 cu. ft. argon tanks for $120, so now I have one in my garage. We'll see how it works.

[Chips O'Toole]

I was about to try using the pure argon with stainless, but I saw a Youtube video where some guy said MIG-welding stainless with pure argon gave really bad results. Is argon really the way to go? I will eventually need the bottle for TIG anyway, so it won't be wasted, but I would like to use the right thing for MIG.

[Coldman]

At welding school we used 100% argon for thin 304 when migging. Seemed OK at the time. Maybe the school didn't want to bone up for expensive gases.

Miller site says use trimix only.

Our big gas manufacturer here in Oz says to use:
Stainshield for up to 1/4" thickness - 98.5% argon and 1.5% oxygen
Stainshield Heavy for thickness greater than 1/4" - 35% helium in argon + 2.5% carbon dioxide.

Personally I think C25 would be a mistake as there would definitely be carbon pickup altering the composition and properties of the surrounding parent and fill.

[Coldman]

If its getting too complicated the other alternative is that there is now a gasless fluxed core wire available:
https://www.amazon.com/Blue-Demon-stain ... B00G5GHUBU

[PeteM]

I was about to try using the pure argon with stainless, but I saw a Youtube video where some guy said MIG-welding stainless with pure argon gave really bad results. Is argon really the way to go? I will eventually need the bottle for TIG anyway, so it won't be wasted, but I would like to use the right thing for MIG.

I tend to blame the indian rather than the arrow. I've used argon once and it worked just fine. The rest of the time was with tri-mix, as per the codes and specs, but Jody among others have used argon with great results.

[Poland308]

Think they use 95/5 at the shop.

[Otto Nobedder]

Try 100% argon for short-circuit MIG. Any position. Love to hear your results.

[Chips O'Toole]

I decided to try the pure argon, since I already had it. I am attaching a photo. This is a flea market 1 1/16" wrench I'm turning into another bottle opener. Does the weld look okay?

I didn't get any spatter, really. I got a lot of soot, though, and the welder made a racket. For some reason the gas seemed to hiss really loud, which I never noticed before. I don't see how that can be right, though. I guess I just wasn't paying attention to the sound when I used 75/25. The pure argon kept blowing crap (soot, etc.) right off the wrench. The soot would attach, and then the argon would blow it off in sheets.

I don't understand why I can't control the wire better. I have it on a very low feed rate, and it seems like it still piles up in a big hurry.

I learned one new thing: don't use rare earth magnets close to a weld. I threw a few small magnets on the work to hold it in place while I tacked it, and I left them on while I finished the job. I found them on the floor later, demagnetized.

If you're wondering why I'm ruining wrenches, I just felt like repurposing junk tools to give me an excuse to weld.

[Chips O'Toole]

Here it is cleaned up.

[cj737]

The issue you were having was more likely due to the magnet than the gas. Magnets pull the arc all over the place. This can also disrupt the shielding gas (makes it behave like theres a breeze blowing across your work). That weld cleaned up very nicely.

Repurposing junk tools to experiment and learn with is a great and inexpensive way to learn new techniques.

[Chips O'Toole]

The magnet problems came as a surprise to me. I've used magnets for tacking many times in the past without difficulty, so I figured it was okay to leave magnets in place while finishing a weld. They were in a place where it was not that easy to remove them, so I just kept welding.

[Otto Nobedder]

The magnet problems came as a surprise to me. I've used magnets for tacking many times in the past without difficulty, so I figured it was okay to leave magnets in place while finishing a weld. They were in a place where it was not that easy to remove them, so I just kept welding.

You will ruin magnets by overheating them. The rare-earth ones are the most sensitive to heat, but you can destroy any magnet by leaving it too close and welding past it.

Steve S

[exnailpounder]

The magnet problems came as a surprise to me. I've used magnets for tacking many times in the past without difficulty, so I figured it was okay to leave magnets in place while finishing a weld. They were in a place where it was not that easy to remove them, so I just kept welding.

You will ruin magnets by overheating them. The rare-earth ones are the most sensitive to heat, but you can destroy any magnet by leaving it too close and welding past it.

Steve S

If you think magnets screw up mig welds, try tig welding near a magnet.