Michael,
Remember that the solder always follows the heat. If the solder is
not flowing into your joint you may not be heating the center of the
joint. I will tell you how I have soldered thousands of rings over
the years. In the very beginning I would cut the ring with a saw.
Stretch the ring up on my mandrel to the desired size. Take a piece
of sizing stock and measure out the size I needed cut and file to
fit. I did not have a way to tack it at the time so I would use the
pressure of the shank to hold the sizing stock in place. Dip the
ring in a small jar of boric acid and denatured alcohol. Set the ring
in the third hand tweezers. I would have a little pile of solder
pallions (squares) that I had precut with shears sitting next to the
third hand on a fire proof surface. I would use a liquid flux and
brush it on the joints.
I would light my torch. Not too soft not too hard. Burn off the
Alcohol while that was happening I would heat up a couple of pallions
for each side of the joint by letting them ball up on the tip of my
tungsten soldering pick. I would heat up the joint moving the flame
around the joint top to bottom until it reached the desired
temperature.
At that point I would move the flame to the bottom of the shank while
at the same time placing the ball of solder that was still stuck to
the tip of my soldering pick to the inside of the ring at one of the
joints. If done correctly the ball will melt as soon as it hits the
metal. I would remove the flame and pick up the other ball of solder
and do the same thing to the opposite joint. Always keeping the flame
on the opposite side of the joint the solder will always flow to the
flame. A sizing down is the same except it is on joint. This has to
be done in one smooth orchestrated act to have it all come together.
Try it on some down sizes.
This was the fastest way to size a ring up and down that I knew of at
the time. I learned that the more Unnecessary steps I could eliminate
the more sizing I could get done. I went from a steel pick to a
tungsten pick the tungsten picks up the solder much better. I found I
could save time by buying precut pallions which were not that much
more than sheet solder and worked better for me. Instead of cutting
rings and sizing stock with a saw I bought the smallest red bolt
cutters I could find (Sears) they worked great.
I discovered GRS and bought their ring cutting tool it allowed me to
get the right size for going up on rings and I use the red cutters
for going down. I found if I rubbed the sizing stock on the joint it
would score the gold eliminating the need to measure the stock and
mark it. Instead of filing I used cut off wheels to even out the
joints on sizings. Instead of using an inside ring file I bought a
carbide burr that would allow me to grind away the excess gold on the
inside of the ring saving on silicon inside ring barrels.
Instead of a brush for flux I bought a bottle with a steel hypodermic
needle on the end this allowed me to squirt flux in the joint while
it was hot if it did not flow and most of the time it would flow. I
put a rubber carborundum wheel on one side of my buffing wheel so I
could smooth out the edges of rings after soldering them and save
time on filing. These shortcuts allowed me increase the amounts of
sizing I could do in one day. If you do not want to save time there
are many ways to get solder to the joint and get a ring sized this is
the way I have done it.
Sorry this is so long but I wanted to get in most of my tips.
Hope it helps