If you’re dealing with cast, perhaps rough or textured interior
surfaces such as one gets with waxes that have been hollowed out,
perhaps with a small ball burr or the like, then that surface
finishes very well with the magnetic pin type tumblers. barring
that, sandblast or beadblast also works very well.
For the actual interior surfaces of ring shanks, which normally get
sanded and polished, a couple products for the flex shaft come to
mind. First, are the 3M diamond band sanders. These are sleeves that
fit over a rubber ended expanding mandrel, with the type of 3M
diamond abrasive that looks like lots of multiple little dots.
Available in a wide range of grits. It use first a quite coarse one,
200 something grit, I think, and then a 600 grit one after that. The
bands, if used with a bit of lube (bur life works fine), last a long
time, and remove metal significantly faster than other sanding drums
or tools I’ve tried.20
If you’re working silver or gold, then the fine surface from that
fine sanding band will polish up just fine with standard buffing
motor tools (felt fingers, etc.) If you’re working in platinum, it
may save you yet more time to sand it finer yet, and I recently
discovered an imported sanding drum that amounts to fine sandpaper
wound on a mandrel. Sounds conventional enough, but these are pre
mounted, permanently, on their mandrel rather than the usual
cartridge rolls… Made in Japan, and they use a significantly
thinner and finer paper abrasive than conventional abrasive rolls,
so they run very smooth and true. Last a good long time too. As with
normal cartridge rolls, you peel back the paper as it wears. But the
really neat thing about them is in addition to more usual grits for
cartridge rolls, you can get these things in even very very fine
grits. I use the 400, 600 and 800 grits in particular. The 800 leaves
a surface that you can take directly to rouge if you wish, even on
platinum. Stuller carries them (the diamond sanding bands too). I
think Gesswein does too, and others may as well. In time saved and
better results, they’re well worth the somewhat higher cost over
cheaper abrasives.
And the final little tip I’d pass along is regarding putting the
final rouge finish on the insides of ring shanks. Many polishers use
only the felt finger shaped buffs, and these work well enough. But
the things are rather easy to contaminate with coarser grit, and
sometimes getting a perfect rouge polish, without faint scratches or
drag marks, can be difficult on some pieces. One solution is to get
one of the small mandrels, similar to the type used for the MK
brushes, but that has a fine tapered threaded spindle on the end.
This tapered spindle comes to a fine point, much finer than what’s
on most buffing machine tapered spindles to start with, so you can
mount very small wheels on it. The one I’ve got has a wood hub, which
then mounts on the main spindle of the buffing motor, but I’ve also
seen them in plastic. Anyway, with these, you then can use the tiny
little loose 1/2 inch muslin buffs that normally get mounted on a
screw mandrel and used in the flex shaft. Use these with rouge on the
main machine, and get to hold the ring properly in both hands while
you buff, while not breathing in all the rouge from the flex shaft
use. With these small buffs, unlike the finger shaped felt buffs, you
can much more easily vary the direction of buffing a bit from side to
side, avoiding drag lines, and the softer muslin won’t give you as
much trouble with scratching or the like. Works like a charm. Most
polishers wouldn’t normally consider the finish from a felt wheel,
even with rouge, to be the final surface on an exterior face of a
ring, finishing the surfaces with muslin or other softer rouge
buffs. But many of these same polishers will struggle to get a good
finish on the interior of a ring, not quite realizing that the tools
are there to use the same muslin buff sequence on the inside of the
ring as well.
Hope that helps.
Peter Rowe
