I have tried many times to do this, but I can't get the wire that
extends through the bead to ball up. It seems to have too much of a
heat sink. I've assumed that my flame just wasn't hot enough. I use
an acetylene/air torch. Would you please let me know what type of
flame you use.
Your problem is that torch. You need one with an oxygen line as
well. The acetylene/air torches are wonderful for general
silversmithing in part because the spread the heat out so well over
larger areas, and since silver needs this overall heating for good
soldering, they’re great. But when you need hot pinpoint intense
heat, then you need a torch with oxygen too. I use propane and oxygen
in either a little torch or a meco midget. Either one works, as
would other fuel/oxygen torches such as hokes, or others. Natural gas
or acetylene or hydrogen fueled torches would also work. The
hydrogen/oxgyen torches, including “water” torches would work
especially well because their flames are especially narrow, and with
the water torches, the vapor fluxing unit also would help cleaning
balling up the wire.
With your torch, though, balling up a wire next to a heat sensative
bead or pearl is likely not going to work too well, as you’ve found.
Instead, look at the suggestions Leonid gave. The thought of a couple
I’d forgotten about, like threading the wire, threading a hole in the
base, and riviting over the end of the wire after screwing it on.
That would not come loose, and because you ball up the wire before
it’s anywhere near the bead, your torch will work just fine. Also has
the advantage that you can try several times if you decide you don’t
like the shape or size of the ball the first time, which is hard to
do if you’re balling up a wire end as the last step, when the wire is
already affixed to the piece. If you’re not equipped to thread the
wire and the hole, riviting the end can work too, though sometimes
that can be slightly difficult to hold in place to do, since the
other side of the rivet is your bead, not something you can easily
support on a solid surface without damaging it. Instead, if you can
get to it with a pair of small round nose pliers, wind the end of the
wire extending through the hole into a small coil. You can simply
keep winding up the wire till it pulls tight on the other side. If
the wire is strong enough, ie not dead soft and a heavy enough guage,
this may be quite secure enough all by itself. If you’re not sure,
add a drop of super glue to the coil and where it contacts the metal
around the hole. Don’t overdo this, as you don’t want it flowing
through to the front. I’ve seen antique pieces where much the same
was done, except not bothering with the coil, just pulling the wire
tight and then bending it over. The a small bit of soft solder
(lead/tin in those days, nowadays use TIX. looks better, melts even
lower, and stronger) to hold that bent over wire in place. I don’t
ordinarily recommend the use of these solders simply because these
days, we don’t often need them, and they do present problems if you
ever have to work on the piece again. Plus they’re not at all as
strong as a proper silver solder. But this type of use is a
reasonable place to use it, especially if the spot you’ll be putting
the soft solder on is hidden in back. You don’t even need a torch.
You can do it with an electronics type soldering iron (the larger
capacity ones, not the very tiny circuit board types, since even
with soft solder, you have to contend with the heat sinking ability
of the silver.)
cheers
Peter Rowe