Welding thin metal

[David]

What is the best technique when butt welding automotive sheet metal? I've been playing around on an old Firebird and noticed a few things while welding with a .30 flux core.

1...pushing the puddle back on itself get great penitration with little spatter.

2..a very thin gap is better

3.. vertical welding is a b&^ch( I think it's more being out of position than anything)


Would changing to gas change anything other than the constent cleaning of the flux residue?

Thanks
David

[Guest]

Lap weld with the new metal underneath. Tack every inch or less. Weld vertical downhill, torch toward the weld. Dolly the weld bead after and lead it in. You will get less warpage than a straight butt weld.

[David]

Thanks Rocky, I'm just playing around to improve my welding habits before attempting the body work on a more important restoration where a lap seam wouldn't pass mustard in a show. Otherwise I would lap the seams. I've gotten perfect welds at times and other times it would just ball up. The MIG was given to me and is an older Millermatic unit. It could just be time to find a new unit with new electronics and controls.

Thanks
David

[Mike Sherman]

I have done this a few times for some of the local enthusiasts. Bare wire is definately better. I prefer the smallest wire you can get and a 75AR/25CO2 gas. Clean your metal as best you can without making it too thin, if you can't lap it a Rocky said, then leave very litttle gap, tack it alot say every inch and pull the weld. I often will use an exagerated pulsing action. This is the specialized welding technique every welder will sooner or later have to learn when he burns through a thin piece or fills a hole. It works very well on automobile sheet metal. Pull the trigger, stop (don't move), keep your helmet on, let the red cool out of the puddle, pull the trigger again. You will develope a rhythm and it will progress nicely. People who weld on cars more than me may well have a better technique, if so I am also interested in how they do it. Good luck.

[Tim135]

Welding on autos

I used to do auto body work professionally for 15 years. I used a panel stepper tool for patching holes or welding on patch panels. It is a vise grip with jaws , that when compressed along the edge of the panel, will step the edge down about the thickness of the panel itlself. This allows you to lay the patch panel on the step which is slightly lower or inset thereby allowing your new panel or patch to lay flush with the old panel. These tools can be ordered from most auto body supply stores. It's been many years since I bought mine but it was around $30. They also make a pneumatic panel stepper if you feel the need to install big panels or patches. Hope this helps.