Stovebolt.com Forums The Shop Area Paint and Body Shop Thin metal welding frustration

I had a frustrating day today trying to weld in a patch panel in the footwell side panel. Metal is so thin there I kept blowing holes. Just had to quit for the evening

What do you do when the metal is so thin?

Get shorter on the trigger. If if still blows holes work it back to good metal and then close the hole.

Cut that thin stuff back till you get to solid metal. It's not worth chasing the holes all over the place.
Once you get to solid metal, use quick blips on the trigger. Even with good metal, you don't want to run beads like you would when welding 1/4 inch or thicker steel. Check the sticky thread up at the top of the forum on MIG welding sheet metal.

Thanks guys. I think now I got it solid. It's just going to be paper thin in places

I second that you’re on some sort of residual, thin, rusty spot. They are a pain to stop blow through.

If accessible, a copper backup plate will work wonders for you. I have a chunk of 1” copper pipe that I’ve cut up in various ways. I’ve used it in its original circle 2-3” long, uncurled sections, created little square L shapes, wrapped a flat piece over a dolly, and even put some over a piece of flat bar. The heavy metal acts as heat sink for the weld, the copper prevents sticking, and overall greatly reduces blow through and it also creates a nice flat backed weld that is easier to planish if need be.

They are handy.

Thank you Fox. Yeah I learned about that trick and have a flattened piece of pipe. I wish I could get it behind that thin metal but not possible.

Sometimes it's going to be necessary to put a scab patch over the thin spot and metal-finish the bulge that's created by the thicker area. A little metal finishing and a thin layer of Bondo can hide a multitude of cobble work. The nice thing about sheet metal work is "If it looks good, it IS good!"
Jerry

Get an oxy-acetylene rig and learn to braze or scab patch as Jerry says and use a silver-bearing solder like Stay-Brite. It will be as strong as goat's breath and the joined part will never rust.

The trouble with solder is that the metal has to be CLEAN for it to stick. Brazing alloys are a little more forgiving, as they usually require the base metal to be dull red, which usually means the rust is burnt off.

After looking at it again today I'm taking your advice Kevin. I'm going to order a new patch panel and patch a larger area in order to get to thick(er) metal. I don't want to leave it like it is. Not happy with it.

Thanks