The piece of bronze I use the most is 2"x3"x1/4" with two corners 90°. Another corner is rounded lightly about 1/4" and the other corner rounded about 1/2". Depending upon the job I'll use whichever corner works best or if I'm able to I'll use the piece behind the piece to be welded. This weekend I needed to fill a 1/4" x 20" gap on a 1967 El Camino quarter. I couldn't get behind the quarter so i lightly wedged the sharp 90° into the gap starting my arc on the bronze piece where it touched the base metal of the quarter then running the bead over to tack to the other side of the gap. Jumping around to avoid hot spots. Took about 15 min until each tack was about 1" away from the next...quarter panel maybe 100°F. Let it cool about 15 min then filled in between each tack until only 1/4" between tacks. Let cool again then filled in between every other gap. Cooled then welded. 100% seal welded with no distortion. You'll see after you screw around awhile. Don't overheat...warm to the touch. BTW gas is best for shielding but if you have to use flux core wire be sure to neutralize the acidic flux with TSP (Trisodium Phosphate). Buy a box of TSP at a hardware store and mix per instructions. A cup of liquid mix will go pretty far. Another F'n Old Guy trick.
