If you use a piece of 1/4 inch by 1 inch or heavier bronze, brass or copper and clamp it to the outer surface and weld the crack from behind, you will end up with a relatively smooth surface with few pits and no splatter to contend with. Will require minimum grinding and you can grind from the back side. save you a lot of time. you may have to move and clamp the backing metal several times depending on the curvature or length of the crack being welded . The weld will not stick to the non ferrous metal
F Y I... The weld won’t stick to copper, but you may find it will occasionally stick to brass or bronze.
H.F. sells a copper welding "spoon" for backing welds, as noted in Dennis' post, for weld filling holes, and for heat sinking. Good tool for little money.
Now THAT'S a great trick! I'll remember it the next time I want to avoid an "unsightly" weld. Thanks!
I have used pieces of copper water pipe as backups to weld up holes on curved surfaces with good luck. If the diameter of the pipe is too small, just split the pipe and open it up to suit. Hold it on with c clamps or vice grips as required. Cheers, Bill
It's called a heat sink! Mine is a piece of 1/4" thick copper, 4" long and 1" wide. One face is slightly radiused so that it will closely follow the underside curve of a T fender, the other remains flat. I find it allows me to keep the heat up in the weld so less weld material is left proud to be ground off later. At the same time it reduces the likelihood of burning a hole in sheet metal.
William, your copper pipe idea has merit. It would be easier to make conform to different curves.
Allan from down under.
The Flap Discs in your 4-1/2" angle grinder are magic for smoothing welds in sheet metal.