How the heck do you get resin core solder to adhere to spring steel?
bob

Surface prep past heat treat scale to bare scuffed fresh steel and thoroughly degreased.
Depending on thickness and length, could be cooling as a radiator and not enough heat for solder to flow. Resin to steel first for surface wetting, and may end up heating enough to ruin any spring to the spring steel.

Tnx; ruining spring isn't a consideration.
bob

Both surfaces to be joined and using a spring clamp to maintain pressure while heating part to solder flow and adding more to fill gaps. But generally all solder problems come from contaminated surface and/or not enough heat.

This was VERY thin stuff, think tape measure thin. Decided my pin point pencil tip iron didn't heat things enuff and will buy a chisel point iron before I do this again. For the sake of expediency I drilled holes and used pop rivets. It worked!
bob

I could solder copper wires just fine but when I tried to solder to steel it never worked. My father told me it required acid core solder. I might have been trying to solder to something too thick to heat up properly. In years since I've soldered steel electrical wire to copper electrical wire and it worked just fine.

Will break at holes otherwise....thin stuff just preheat and dip in melted solder pot for tinning, then clamp and heat...torch probably better than iron...

Nt

Yup, the joints are pretty well supported.
bob