I'm looking at purchasing a 78 Chevrolet truck which has some modest rust which would most likely need to be taken care of via replacement sheetmetal and welding. I'm a decent welder (a little better than a hack). I understand how to strike the arc, create a puddle, and generally get two pieces of metal to permanently stick together.
One of the issues I have when welding thin sheet metal like you find on vehicles is, the metal is too thin and I end up blowing through it (burning holes in the metal where I'm welding). This makes a huge mess because if I really want to get it done right, I then have to cut it all back out and basically start from scratch. To this point, most of the welding I've done on this type of sheet metal is only just trying to get metal to stay put and to heck with the aesthetics. Well, if I get this truck and want to do the sheet metal work on it, I'll need to do a better job and get it right on the first go.
My questions are:
- How do you avoid blowing through the sheet metal on vehicles?
- What techniques are best suited to providing the best overall finish?
For reference, I'm using a light duty mig welder. I have four power settings and a wire speed range from 0 to 10 (arbitrary, I know). It is a 240vac welder @60Hz. I use flux core wire which is .030" thickness. I'm do have .035" thick wire which I will go to when the .30" runs out (pretty soon).