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NSDesign
11-07-2004, 03:46 PM
I am a welding newbie and have two questions about welding stainless. Material is 304 structural shapes 1/8 and 1/4 thick. I was thinking 308L .030 solid wire. I have a Hobart Handler 175 and am running 75/25 shield gas. Application is mostly decorative, the welds need to hold and look good, but will not be holding 10,000lbs over a gaggle of nuns and infants.

First - can I get away with the 75/25 or do I have to have tri-mix? What should I expect?

Second - is there anything else wrong with my plan (wire, welder, etc.) I have heard a wide range of stories - Everything from how impossible it is to weld stainless without professional size gear and talent, to "it welds just like plain steel, don't sweat it."

Before I shell out the bucks for material, I would love to make sure it will all work out.

Thanks,

Alan

aboard_epsilon
11-07-2004, 04:03 PM
LOOKS GOOD TO ME
the only thing you have to remember is to crank up your amps more than mild steel or you wont get the ss to flow out and it will be beady.
usually about 10-15 percent more.
not sure about your gas .as the gas here in the uk i use is argoshield-5 this stuff seemed to work ok.
175 amp welder is plenty enough .
there again im only an amature ...but Ive had good results.
all the best...mark

JRouche
11-07-2004, 04:32 PM
Hello, I actually prefer to weld stainless, it welds very clean. I have not MIG welded stainless though. When MIG welding steel I use the argon/CO2 mix. But when welding aluminum with the wire box I use pure argon just as when TIG welding. So I wonder if you wouldn't use pure argon for the stainless also? JRouche

[This message has been edited by JRouche (edited 11-07-2004).]

klemchuk
11-07-2004, 06:17 PM
I've done tons of stainless with a mig setup. Use trimix or argon! 75/25 just won't cut it. best of luck

wierdscience
11-07-2004, 08:59 PM
I'll second the tri-mix,also it helps to purge hollow tubes with gas while welding.
Gap weld everything,don't fit the parts up tight,it will pull more than MS or Al.
A wire brush and a bottle of alumi-brite work good for cleaning the soot you sometimes get off the surface of the weld.

ibewgypsie
11-07-2004, 09:06 PM
Mig and a auto-dark helmet.. I posted some stainless tattoo machines I made a week or so back..

David

maddog
11-07-2004, 09:34 PM
Straight Argon

JRouche
11-07-2004, 10:45 PM
After consulting with one of my welding guides (Modern Welding) I would use the tri mix, maybe.

It states the mix helps prevent undercutting, provides arc stability, has a smaller heat affected zone along with minimum distortion.

Like I said, I don't (never have)used MIG for stainless (love to use TIG though) so I am just passing info along. The mix they specify is 90% Helium, 7.5% Argon, 2.5% CO2.

Is that what "tri mix" is?

Personally I don't use Helium anymore due to the cost and the better performance I get from Argon when TIG welding, heliarc no-more. JRouche

maddog
11-08-2004, 10:33 AM
Helium makes more heat. I use helium/
argon blend for real thick aluminum,
(over 1" thick)

Straight argon works as well as anything
and is cheap. Unless you're welding real
thick metal, I'd stick to straight argon.

Forrest Addy
11-08-2004, 02:43 PM
Stainless can be a little tricky when welding high confidence pressure pipeing like in nuclear reactors but at our shade tree level stainless is a piece of cake.
Stainless welds so easy, it almost welds itself.

I'm not a MIG expert but your set-up sounds in the ball park. Try a few samples. Refine your process as you practice with it before you move on to the production work.

If you want to be sure you work stays birght ofer years in the weather, be sure your weld preps are spotlessly clean. The least amount of organic material can bleed carbon into the weld puddle that will leave a blood rust site.