Sorry weldequip, you are wrong! What kind of steel? Plate? Cold drawn tube? Forged? Theres possibly two or more gases for a start! What kind of aluminium? Extruded? Alloy sheet? Hot / Cold forging? Die Casting? Theres more...
My own personal answer to this question would be one gas! Why? Because I wouldn´t even think about using a MIG for Stainless, Aluminium or Copper!
There is only one way to weld. Correctly. If a budget doesn´t allow the use of the correct method, then either give the job to someone who can do things in the correct manner, or wait until the budget allows. Remember this. Be it amateur or pro, lives could possibly depend on a weld holding! Dont know what anyone else thinks, but life is precious.
Weldequip, I suppose that you can say that your original answer of two bottles was correct, on the condition that the second bottle can be filled with the gas of choice. Can that be done now in the UK? So to find a compromise, two bottles are enough, two gases aren´t!
Regarding steel plate and cold drawn tube. For mild steel plate, I find the optimum method MIG. For Cold Drawn tube, both MIG and MAG are No-Nos! The optimum method here would be Oxyacetylene (braze-weld, not fusion). For one to the other, Oxyacetylene again.
Though it is possible to MIG weld stainless steel, and some types of Aluminium for that matter, I always TIG weld them. The results are better, and I have the equipment anyway!
For me, Cold Drawn tube and Mild Steel tube are two completely different materials. Therefore the only thing that I am differentiating between is the materials. But you do have to be careful, and know exactly what you are welding. Remember that certain grades of Mild steel are classed as High Tensile! Also, certain (for lack of a better word) authorities will only allow Cold Drawn to be brazed!
As far as stainless goes. Yes, it is possible to Mig weld it. Yes, the results can be acceptable. But, a perfect TIG weld is both neater and more reliable than a perfect MIG. If you ever get the chance to comparison test the two, you will see exactly what I mean.
Aluminium. If we are talking say some sheet material, or some extruded, then both MIG and TIG are ideal. It basically depends on the operator. But if you are talking say a sand casting, such as a cylinder head, TIG is ideal, whereas MIG cant be classed as more than "not realistic!" Though even here, MIG may be better than some of the other methods we used "back in the day!"
Mild Steel with a tensile strength of over 260MPa is in fact classed as High tensile! Plate and cold drawn are NOT always the same steel!
No its not, the usual definition is 500 or 600 Mpa but even that is unofficial. In old money 260 Mpa is 19 tonnes / Sq in for those that remember when we used to class HT as 30T +
As I have said before on this site, Manganese Molybdenum should be SIF Bronze welded!
I was referring to small quantities of Mn Mo etc in Steel
Rally cars. If they are using Chrome Moly tubing, then it should be TIG:ed!
I agree and ive never posted otherwise but YOU posted earlier that it had to be BRAZED
OK, I´ll change the "No-No" to simply "No."
is that any different, its still wrong
The only urban myth on this website is that MIG is best for everything!
Is that what I posted....please read thoroughly
I think it is a fact that for amateurs the Mig is the most versatile welder of all is it not? I`ve welded up a stainless bed frame with MIG. The wife and I aint broke it yet. You can`t test critical welds better than that!!
Alex