Posted by Sam in Ohio on Sunday, September 14, 2003 at 5:29AM :
In Reply to: Mig Welding advice needed posted by Rick on Saturday, September 13, 2003 at 3:26PM :
I'm only a novice, but this is my experience: If the two materials you are welding are mismatched, they will have different melting points. One will burn-away before the other melts. I have experienced this welding thick patches into rust-thinned running boards. For best results, use same guage and carbon content metal. This may mean cutting more than just perforated metal out, but also the thin stuff nearby. (I have read that one can judge similarity of carbon content by looking at color of sparks when grinding a piece) Rightly or wrongly, I have held on to some good sized pieces of scrap PW sheet metal to use as patch material. Someone once posted on a forum that Volkswagon Fox panels are of similar composition to some vintage metal (but I would assume much thinner)
As far as gas setting, there should be a chart with your machine (10 would seem like a good start). The numbers given are only accurate if there is no wind. If I am outside, I double the setting and try to shield the wind if possible.