Most versatile welding gas?

[ericjon262]

I'm looking into buying a new MIG welder next week, and I was wondering what type of Gas I should get. I plan to weld anything from stainless to aluminum (I know spoolgun...) to iron! anyone have a recommendation?

Thanks-

Eric

[onefastV6]

From what I have researched, the recommendations are as follows to get the best weld:

For aluminum 100% argon
For stainless 90% helium, 8% argon, and 2% CO2
For mild steel 75% argon, 25% CO2

I am not sure if there is a "one gas fits all", but I would be curious to know what you find out.

[unchained01]

+1 and what kind /brand of welder ? Small portable 110 volt or shop style 220 volt ?

[ericjon262]

220V, Lincoln pro mig

http://www.lowes.com/pd_256723-1703-K2481-1_4294772337__?productId=1072947&Ntt=welder&pl=1&currentURL=%3FNtt%3Dwelder&facetInfo=

I'm getting a pretty good deal on it, $350-$400 (hoping $350!) I'll need to get a bottle too though, and I'd prefer to buy one instead of two or three... I'll most likely get at least 2 bottles, one for stainless, and one for aluminum, I don't see why I couldn't weld mild with straight argon instead of the 75/25 mix.

[unchained01]

Yeah thats a hell of a deal almost 50% off !!

[geoffinbc]

That MIG welder wont do any "real" fab work. Its better suited for body panels. Get a Miller 212 or Lincoln 216 at minimum. Either one of the 250 series is an awesome welder for a guy starting out in fab.

and 85/15 gas is what I would recommend. Less spatter and the option of spray transfer. The use the same gas with a flux core wire for welding stainless. Aluminum requires 100% Argon or a Argon mix with 2% Helium. Helium will increase wetting but as you increase helium spatter increase and so does arc instability.

[geoffinbc]

I'll most likely get at least 2 bottles, one for stainless, and one for aluminum, I don't see why I couldn't weld mild with straight argon instead of the 75/25 mix.

You don't weld SS or Mild steel with straight argon. Argon gives horrible arc stability and poor bead appearance. It is acceptable for down-hand spray transfer welds. But they are only used for gauge steel. Get a 85/15 blend and use flux core when you want to weld SS. Its cleaner, stronger and easier to weld then straight MIG on stainless.

[ericjon262]

my main concerns right now:

welding up my headers (stainless)
budget.

Most of what I weld is sheet metal, so I feel like this should be adequate for the time being.

[geoffinbc]

What grade?

304 can just be welded by that machine. You can run 0.030" 308LSi MIG wire with a 90%He/7.5%Ar/2.5%CO2 Tri Mix this will get you short circuit transfer at 17-19V which that machine is capable of. It has a max of 20V output which is why I would relegate it to sheet metal use.

If it is 409 stainless you can use a low alloy wire with 85Ar/15CO2 or 309LSi with the same gas I mentioned above.

The 308LSi or 309LSi wires are low carbon with silicon to reduce carbon buildup in the weld and heat affected zone. This will increase the resistance to cracking and increase corrosion resistance versus a standard 308 or 309 wire.

[geoffinbc]

If your looking for a smoking deal on welders then check craigslist. Here there is an $8000 (when new) TIG machine for $2200. It is in mint shape and has a cart too. There are MIG machines that are $3200 new for $1200. Welders don't really go bad until they get old and a board might have a fried component. Usually you can order a replacement board for a few hundred and plug it in yourself. I use these machines every day and there is nothing worse than a machine that does not have the power you need. It is even worse when your trying to learn.

[ForcedFirebird]

I agree. You need at least a 180amp machine to build stuff, those small welders are good for body work etc.

We just picked up Hobart Handler 190, awesome machine for the money, local welding supply sold it to me for $730 tax and all, out the door.

I only have 2 125cf bottles, they are expensive to purchase, but cheap to refill. I use c25 for the MIG, it welds stainless fine, and 100% argon on the TIG.

[ericjon262]

I agree. You need at least a 180amp machine to build stuff, those small welders are good for body work etc.

We just picked up Hobart Handler 190, awesome machine for the money, local welding supply sold it to me for $730 tax and all, out the door.

I only have 2 125cf bottles, they are expensive to purchase, but cheap to refill. I use c25 for the MIG, it welds stainless fine, and 100% argon on the TIG.

FWIW, the welder I'm looking at goes up to 180 amps, doesn't go over that though.

[geoffinbc]

Its not amperage alone that dictates what you can or cant build. In MIG welding you need to increase the wire feed speed (biggest effect on amperage) along with voltage. These two parameters dictate the total weld energy input. Energy is what you need to make things happen. The problem with these small welders is they typically have a maximum voltage output of 20V give or take a volt. This is what really screws you when you want to weld thick steel. You can go ahead and increase wire feed speed to try and get a good bead size and more amperage but what you end up with is barely any penetration and a skinny bead that appears to just sit on top of the steel rather than be melted in. Down the road you end up with cracking and tears in your weld.

You can bandaid this situation in a pinch by using thin wire (0.023 or 0.030), a minimum of 200*F preheat and 250*F inter-pass temp and instead of trying to lay down one big pass do two or three small passes with cleaning in between. How do you know when you are at 200*F? Drip a bit of water on the weld zone and look for a rapid boil or even spit on it! No nasty lung butter loogie though! Preheat can be a problem if your working inside on roll cages or brackets though.

[ForcedFirebird]

180amps being fed by 120v still won't cut it. A local built his cage using a 120v welder, then loaned the welder to my other bud to put a cage in his car. When I saw how little penetration he had, I demonstrated a weld on a piece of cage, whacked it with a hammer and it literally broke right off. He is now nervous about piloting the race car that had the crappy welded cage. Would suck to be impaled in an accident by the very object that's supposed to save you.

[geoffinbc]

While I agree with your point it is not input voltage that is the determining factor. It is the output ratings you need to watch. While a typical 120V household plug is a limit on output because of the typical 15A breaker rating. In the end its all about whats at the gun.