[EricVanWyk]

Big copper wire is a pain to solder, as it is essentially a giant heat sink. The secret is to get the entire thing hot. I'd recommend baking it in the toaster or microwave until it gets good and crispy, and then quickly use the iron to get it the rest of the way there.

As fair warning, you are not using the right tool for the job. I use a 500 Watt Iron for things easier than this.

I would try wrapping the joint with some bare wire to give your solder something to stick to. Might give it a slightly better chance.

Good luck, you'll need it, especially if you think I was serious about the microwave