Mig welding thin to thick

[kamaroman68]

Question???? When mig welding say 1/8" thick mild steel to say 1/16" mild steel you would still use the heat/wire speed setting for the thicker metal correct??? If so when welding the two do you start the bead on the thicker and just kinda roll it onto the thinner metal??? When welding ss to mild steel does it require a different approach than regular mild steel? And finally when welding ss 304 to ss 304 does this require different heat/speed ratings than normal mild steel. Example: My welder recommends using a certain wire speed and heat for 1/16" mild steel. Would the same settings apply welding 1/16" ss 304 but of course using different wire. Thanks Chris

[parsonsj]

Geez Chris, you can sure pack a lot of questions into a paragraph!

I've done this many times, and here's how I do it.

Use the higher settings for the thicker metal. Sideswipe the bead into the thinner metal as you go. Careful, or you'll burn a hole. If you do burn a hole, go to lower settings, fix the hole, then go to higher settings and continue.

If you're welding ss to mild steel, use ss wire and tri-mix gas.

Stainless MIG welding has a different "feel" but the technique is exactly the same. I find that ss seems to want more heat for the same penetration, but be careful, or you'll ruin the anti-oxident properties with too much heat.

jp