Thank you, Ernie. He was using C25 (my mistake), but today he picked up
a little bottle of ar-co2-he, followed your suggestions about stickout
and lower wire feed speed, and things are looking much, much better. He
did have to turn up the current some, not down, but I'm sure that's just
a matter of balancing the wire feed speed and welding speed that he is
using. The beads look clean but there is a little "halo" of black
sooty-looking stuff alongside of each bead. Is that just as good as it
gets, or is it possible to make it look as clean as TIG?

--
Regards,
Carl Ijames

"Ernie Leimkuhler" wrote in message
...
In article , Carl Ijames
wrote:

Basically, how do you do it? We need to weld up some structural
304SS
pieces (3/8" rod welded to 16 ga C channels, and other stuff of
similar
size) and TIG would just take forever. Our welder is great with MIG
and
mild steel, and TIG on aluminum and stainless, but so far hasn't had
any
success with MIG and stainless. He is using 308 wire (0.035 I
think),
pure argon shield gas, and dc reverse polarity (I think; whatever is
normal for TIG and SS). Practice beads on 16 ga sheet have way too
much
heat and penetration. Any advice and experiences would be very
helpful.
Thanks.

--
Regards,
Carl Ijames



Wrong gas.
You want a Helium or Oxygen Tri-mix.
Argon-CO2-Helium, or Argon-CO2-Oxygen.

Argon is way too cold for MIG on Stainless.

Pure Argon is used for MIG aluminum.

You can run a C25 gas (75% Argon, 25% CO2), but the welds will be
really gray, and you will get more spatter.

Keep the wire stickout as short as possible.
You want the contact tip flush or even a little pround of the gas
nozzle, not recessed.

Stainless steel wire is really bad at conducting power, so you have to
keep it as short as possible, and use a really hot gas mix.

He will have to weld fast or just dial the machine way down.
Try 16 volts, and 160 Inches /Minute.