I have always struggled with soldering wires to transformer lugs, especially lugs with multiple wires attached. It seems like between the thickness of the transformer lug and the multiple wires (in my current struggle, three thick wires on the same lug) that the mass of it all creates to much of a heat sink. I've been trying to solder this all together with my hakko fx-880d with a 1/4" chisel tip. I've got the hakko cranked up to 630F, but I just can't get the whole shebang heated up enough for anything better than a cold joint which (of course) fails immediately. How do folks usually tackle this type of challenge?