I usually mill ring stock that is slightly bigger than the desired
finished ring. I form a ring that’s about a size smaller. I make
certain that the join is tight and flush. Then I roll a thin piece
of metal and slip it into the join by pushing the ring onto a grooved
ring mandrel to open the join. I weld by focusing the heat on the
thin piece. After I’ve welded from all directions, I hammer the ring
up to the desired size making certain that I hammer from the top as
well as the sides. I want densely compacted metal. From there, I
clean up the ring if it’s going to be a plain band. If I’m going to
set stones, etc., I just rough out a ring blank and clean up the
inside surface. The rest is cleaned up after setting.
Hope this helps.