Seat springs--repair

[MS Fowler]

I have a few broken seat springs. My proposed repair is to cut similar pieces of spring from an old seat and wire them over the breaks. My question is what kind of wire should I use? Steel or copper? Lots of turns of fine wire, or feww turns of coarse wire? I think if I used fine copper, I could flow some solder over the repair and sort of seal the copper, making it a tube-like connector.

An alternate method would be to use aluminum bar stock, and drill out holes corresponding to the broken ends of the wire springs, and insert the ends into the aluminum bar.