[MrForbes]

for heavy wire like that you might want to use a soldering gun. Small soldering irons work great for electronics work (circuit boards) but not for heavy stuff like that.

You do need to have the parts hot enough that the work melts the solder, otherwise it will not bond. And for the job you're working on, a blob of solder holding the ends of the wires will probably work ok. however, if you could rearrange the shape of the wire so the wire ends have some overlap at the solder joint, it will be easier to build and stronger.