What gas for stainless mig?

[BrokenBiker]

getting ever closer to buying my mig now, have had my overtime cleared in work but not sure if it's coming this month or next month but is definitely coming so now I am looking to what I will actually be welding.

Now most of it is going to be 1-5mm (but mostly 1-3mm) mild steel or stainless where it would be welded with a mild steel wire ( welding new stainless exhaust parts to mild steel systems for a friend) but I will also occasionally be welding stainless box section and sheet for my father.

So for the mild I will be going with argoshield light, and was thinking of getting a rent free bottle f what ever is needed for stainless as the welds will be mostly on show so want them spot on

What gas is best for this (up to 3mm stainless, probably 316 as we can get this quite readily for not a lot of notes)

Won't be doing a huge amount so a rent free bottle should last a while and my father will be paying for gas and filler anyway so I'm not really worried about cost

 

[steviec_lj]

The best? Almost pure argon. Something around 98%, with 2% CO2.

Having said that though, we used Argoshield Light and never experienced problems.

 

[BrokenBiker]

Ah fair enough. Might try it with argoshield light first then. That is only 3% co2 iirc

 

[matt1978]

Argoshield light is 5% Co2 and also has 2% Oxygen, the balance is Argon.

Regardless of what anyone else says, you shouldn't use a mix of more than 2.5%-3% Co2 for Mig welding Stainless Steel. This can either straight Co2 and Argon or a Argon, Helium, Co2 mix. There are also Argon with 2.5% Oxygen mixes, but the most common is either the 2.5-3% Co2 or the Ar/He/Co2 mixes.

That doesn't mean that for what you want to achieve, Argo light won't do a good enough job. BUT its not the correct way nor the correct mix.

Depends on what quality level you need to achieve.

 

[BrokenBiker]

Well the welds will mostly be just to hold things in place and won't be taking much wore weight than an empty petrol tank off a motorbike, and the rest of the stuff is for things like a stainless steel pond guard and I made him a stainless door frame to hang a heavy wooden door for his shed, but I stick welded that with dissimilar rods that I nicked from work ages ago

 

[Richard.]

Do you have DC Tig Bb.
That would be perfect for 1-3mm stainless. And for exhausts its a ton nicer than mig

 

[BrokenBiker]

No, I did have until it was nicked last year. The joints on the exhaust won't be visible. Basically my mate has a small set up doing exhausts and buying and fitting alloys and lowering kits etc for people that don't know what they are doing. All I will be doing is waiting for him to cut the existing exhaust just after the cat and then welding in a pre bent exhaust and a flexi then welding mounts on. He is currently using a guy that uses gasless for it but he isn't very reliable so I have said I will take his place when I have a mig again. I did a few for him with gasless when he started first and they came out ok but not a patch on a proper mig, and as its welding stainless to mild there is t much point in using stainless wire. He has all the kit for bending the pipe and he buys in pre made silencers etc so it's just tacking up on the car, dropping it down and welding it up. He is a good guy to work for, has everything clean and ready so I just turn up, weld, collect my money and leave