Got me a little mixed up there Ralph, you say your using "flux core"? So you must have a MIG welder (Metallic Inert Gas) flux core is a MIG wire. Then you say you don’t have the bucks for a MIG welder in the next sentence. Do you mean that your using a little AC stick welder and rods with flux around the outside????
I think Stu is correct, probably just the flux sticking to the copper. Don’t use anything but copper, the thicker the better, if it’s to thin then you can melt it and it will stick. The reason copper is used for a back up is that it conducts the heat much more rapidly than the mild steel, the heavier the copper the better the heat sink! Use enough heat for the thickness of material and you certainly can melt copper. I’ve welded copper many times as an instrument welder at a National Accelerator Laboratory. Flattened copper pipe will work for small holes but it’s relatively thin and if you filling a large hole and have a small piece of tubing you can melt it. Once again, remember, you want a “heat sink”, the thicker the better, the larger the area the better!
Brass---Not good, it contains low melting temperature alloys.
Aluminum---Not good, much lower melting temperature than the mild steel parent metal.
Denny Graham
Sandwich, IL
