Originally posted by fastcougar:
I haven't been happy with my 304SS welding and then I realized something ... I have been using 308SS wire with plain 72% Ar, 25% CO2. I remember reading that a high volume of Helium should be used in the gas mix when using MIG on SS. So, I did some quick research and sure enough, MIGing on 304SS should use what's called a Tri-mix of 90% He, 7.5% Ar & 2.5% CO2.

So, today at lunch, I went by the local gas supplier and picked up a small bottle and let me tell you, this [censored] is expensive! $65 deposit on the bottle, $100 fill for a "small bottle" roughly 3' hight cylinder ... I will check the capacity tonight. That's a lot of money just to lay down a nice bead, but it must be done. Ar/CO2 with 308SS filler wire will cause a contaminated weld, which will weaken the weld and cause it to be more prone to cracking/failing. It's a compromise I'm not willing to live with ... I'm a perfectionist.

Now, I know you must be thinking "but you are only tacking this" ... well, if my fabricator comes back to me with an estimate that is too high for my liking, I'm prepaired to build these myself with my MIG, but I must first perfect my skills. This doesn't mean laying a "good bead", for me, this means laying down a "great bead" that is structurally sound and not contaminated.

I can't wait to get started on more practice this weekend! I just need to pick up some more Acetone for prep work ... I ran out



Try 98/2 a mixture of 98% Argon and 2% Oxygen. Much cheaper, reduces the carbon buildup and allows as good weld bead.
I was going to get tri mix but my welder supplier explained that it worked well and for the money worked very well. I also found info online about it.
Save yourself the cash... and remember that you can also use it to weld normal mild steel, so you can jump back and forth with differnt types of wire with it; making it even more convenient.
Yes, you are welcome.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black