Hello!
So I've been making rings, first in random tiny sizes from scrap and then the right size (or not). Every time I hadn't been able to et the solder join on the first try. I had filed, spring fit the join, sawed though it, fluxed around the join and hard soldered and every time after pickling the ring split open on the mandrel. Then (for practice) I refiled where they split, sawed again and soldered and each second attempt was perfect (and too small).

So, in desperation I made some more rings and after filing and bending, fluxed around the join and heated the whole ring to soldering temp, then pickled, sawed through the join and (for good measure) popped open the spring fit sideways and painted flux on the cut faces as well as around the join, then popped it back in and soldered. Using that sequence I got every solder join first time.

My question is does anyone have any advice as to why my joins weren't working first time before? I'm just looking to understand why my new slightly lengthier method works?

Many thanks
Faith