noob tig / mig question

[JonnoD]

Hi all,
I am looking at buying a welder for general fab work at home. I have done a bit of arch and mig welding as well as some oxy in the past.
My question is are there any things that tig cant do that mig will. Also an i correct in thinking that you can weld ali weth a tig that can do ac. Cheers

[rockcrawler31]

Hi all,
I am looking at buying a welder for general fab work at home. I have done a bit of arch and mig welding as well as some oxy in the past.
My question is are there any things that tig cant do that mig will. Also an i correct in thinking that you can weld ali weth a tig that can do ac. Cheers

Tig can weld virtually anything to anything.

But the draw backs are -

prep and cleanliness need to be better, but most tig machines will also do arc which is fine with a bit of contamination
more expensive gas, and uses a bit of it
needs more than one hand to weld so not as easy where you have to hold the part in place to tack
not as suitable for larger thickness metals. You can do it but the multipass gets old where a single pass with an arc would be easier
much slower process per inch of weld

advantages

you can weld out of position like vert up, overhead, 6G a lot easier and get a better weld
YOU control the process and can guarantee penetration and fusion
potentially a lot neater once you get practiced

and yes, with AC you have the capacity for alloy