Acid core indeed works very well for piano wire, does not require the higher temperatures of expensive silver solder and is far easier to get a good joint over rosen core.

Of course the joint should be cleaned afterward to prevent corrosion but of course this really should be done with any structural joint. And we are talking about structural joints it should not be used on electronics as always.

You will not find Acid core at your local electronics shop (for obvious reasons i.e. not for electrical) but you will find it at your better true hardward stores and its quite inexpensive.

Here are some samples soldered washer/wheel keepers (gave up on collers long ago) on 5/32 landing gear wire. Yes I do use at times soldered on clevis.

John