Are you are installing your patch panels with butt welds, so it is like new when done (like it should be)?
I recommend TIG welding for that. No more than about 1/2" at a time, immediately use hammer and dolly to smooth the surrounding area and use the heat of the weld to help you heat shrink as necessary.
I have not tried MIG welding for the same operation, the guy I am learning from says that it can put to much heat in the panel. It is also often an uglier weld and requires more grinding. Yes a TIG weld is softer and easier to work than a MIG weld.
I am not a professional, and I have only been TIG welding for a few months but almost everyday at work. I am getting excellent results with TIG welding body panels, and I would not try to MIG them unless that is all I had to weld with.
Grigg
