Stainless Question

I did a little repair work for my church Monday. I welded a piece of stainless on our hot plate (buffet table), that holds the glass. I can't say that I have ever welded any stainless. It blacked up on me pretty good, and after I got the hang of it I put down an ok bead. I was using 2% thorated tungsten and 3/32 rods. I know I needed thinner rods. No one keeps any stainless rods in stock, I bought 3 pieces at a local machine shop. The guy asked me what alloy I was welding on. I told him I had no clue, and I was just supporting a piece of plexi glass. My questions are

What do I need to do so the metal will not black up?
Do I need different rods for different stainless?
Is there a good middle of the road stainless?
What tungsten should I use?
Is there a certain way I should hold the torch?

By the way I was using my handy dandy Power Arc 140 ST

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Originally Posted by SeanMurphy265

I did a little repair work for my church Monday. I welded a piece of stainless on our hot plate (buffet table), that holds the glass. I can't say that I have ever welded any stainless. It blacked up on me pretty good, and after I got the hang of it I put down an ok bead. I was using 2% thorated tungsten and 3/32 rods. I know I needed thinner rods. No one keeps any stainless rods in stock, I bought 3 pieces at a local machine shop. The guy asked me what alloy I was welding on. I told him I had no clue, and I was just supporting a piece of plexi glass. My questions are

What do I need to do so the metal will not black up?
Do I need different rods for different stainless?
Is there a good middle of the road stainless?
What tungsten should I use?
Is there a certain way I should hold the torch?

By the way I was using my handy dandy Power Arc 140 ST

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You need a larger cup and higher argon flow for stainless.
1/16 308L filler should be good for food service stainless which is usually 304 or 316.
!/16 2% thoriated will work, if you only have 3/32 then grind it to a finer point.
Hold your torch the same 85 degrees and 15 degrees for the filler rod.

Stainless holds heat so your work can overheat if you try to weld too much at once.

[QUOTE=zoama585;18513]You need a larger cup and higher argon flow for stainless.
QUOTE]

I was wondering if this might be a shielding gas problem. Doesn the black appear on the top surface by the weld, and does it scrape or brush off? I recall a while back there was a discussion of back-ourging stainless steel tubing to prevent black oxidation on the underside of the weld, but this is different.

[QUOTE=DaveO;18514]

Quote:

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Originally Posted by zoama585

You need a larger cup and higher argon flow for stainless.
QUOTE]

I was wondering if this might be a shielding gas problem. Doesn the black appear on the top surface by the weld, and does it scrape or brush off? I recall a while back there was a discussion of back-ourging stainless steel tubing to prevent black oxidation on the underside of the weld, but this is different.

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Just about any metal will soot up without sufficiant shielding gas. For stainless to remain "stainless" in needs good shielding. You can checkout some stainless welding videos at weldingtipsandtricks.comr on youtube.

Before feeling too bad about it, restaurant equipment is hard to weld, particularly used stuff because it is usually deposited with layers of grease or residue and it will black up...If it was used occasionally, maybe not, but anything that sees food service regularly get nasty to weld.

That's funny- I would have thought that manually cleaning and brushing beforehand would clear that up. Other posts have talked about using acetone, for instance, to pre-clean aluminum for welding... is it the same for stainless? Does the black crud come off? Seems like black stains would make the food way less appealing.

the black stuff cleaned up easy, I used 3/32 2%thorated, and the point was dull. I can't remember what cup size I am using.