[Tim Hancock]

Legion, if you are serious about welding mainly thin walled tubular structures, you would be best served with a tig welder, but it takes a bit more time to master. A mig welder typically is the easiest for the average Joe to rapidly learn to use in his garage though. When making relatively short welds on "thin walled" tube clusters, a mig will either start out cold then right as you finish be just right, or will start out just right, then become too hot. With tig, you can vary the heat as needed to keep perfect penetration thru-out the weld. The larger the tube diameter (and weld length) the less of a problem this becomes, but I can tell you that on smaller tubing, a mig welder just will not be able to do as good of a job if the welds are critical.

I learned to weld solely by practising on scrap, reading books and by talking to pros. I had my fill of "school" in my teens and 20's.

BTW, Finch used to run a weld departement making aircraft engine mounts and he claims that only 4130 rod should be used when welding 4130 parts (I agree if the part is later to be heat treated). Well tell that to the Indy teams and aerobatic aircraft manufacturers who use ER80S-D2 on all of their thin walled 4130 tubular structures that will be used in the "as welded" condition. IOW, even the experts will disagree somewhat sometimes and it pays to do your own research.