Hi Tim,
Basically all the Magnetic Finishing Machines work pretty much
the same way although there are some very basic models that
usually run at slower speeds, have a timer and that’s about it.
Then there are the very fancy models that run at the highest
speeds and have various bells and whistles that may or may not be
necessary for the type of work you’re doing.
All Magnetic Tumblers work via spinning magnets in the base that
cause the stainless steel shot rods to tumble furiously fast and
end-over-end in the bowl. The advantage to it is that these tiny
pins get into all the teeny tiny places (including settings,
undercuts, channels, etc.) that no other tumbler/media can get
into and that are such a pain to polish by hand. (Media = the
stuff you put into the tumbler to do the work, in this case the
stainless steel pins.)
When I first saw these tumblers with their tiny little pin media
I thought “Aha, it’s NOT the tumbler at all, it’s that tiny
media.”. So I tried running those little pins in my Rotary
Tumbler - didn’t work. I combined it with standard steel shot
media - still didn’t work. It really is the combination of the
tiny pin media with the high speed action of the magnetic
tumbler that does the job.
Note that because it is steel shot, it only burnishes and peens
the metal - it does not abrade or remove metal. And ceramic and
plastic abrasive type medias just don’t work in a Magnetic
Tumbler. Therefore a Magnetic Tumbler is a nice addition to your
automated finishing line, but it will not make your Vibratory,
Rotary, or Disc Finisher machines obsolete. You still need
those for abrasive work and for polishing of smooth undetailed
pieces.
The Magnetic Tumbler is really best suited for tiny detailed
areas. Smooth surfaces (like ring shanks) end up slightly
“frosty” looking (due to a little bit of impingement by those
pins). Best results I’ve seen using Magnetic Finishing is on
settings with multiple heads, channel sets, charms with a lot of
detail, stuff like that. For example, an eagle charm I saw with
lots of detailed feathers looked incredible after Magnetic
Tumbling - each feather bright and shiny with no unfinished
areas.
Magnetic Tumblers can be used on hard and soft metals.
Generally the cycles times are:
Sterling 30-45 minutes
Yellow Gold 45-60 minutes
White Gold, Platinum 60-120 minutes
Fill the tumbler according to manufacturers instructions
(usually they supply the exact amount of shot needed to fill the
bowl to the proper level). Add water either to the fill line
marked on the bowl or (if not fill line is marked) to a point
about 1/2" or so (it’s not that critical) above the level of the
shot. Add soap according to the directions. Some sudsing is
normal and does not inhibit tumbling effectiveness.
Run the parts for the suggested time and inspect them. Run them
a little longer if necessary. That’s pretty much it.
What can go wrong? Every once in a while the shot will turn
black. This can happen for a variety of reasons including some
jewelry might still have had investement on it (clean the
investment off before tumbling), or you put in the wrong soap, or
just because who knows! It just happens sometimes. Best fix:
Coca-Cola and I’m not kidding! 
Add a 50/50 mix of Coke and
water and tumble the shot for 15 minutes. Empty the bowl and
repeat if necessary 2 or 3 times. Cleans the shot right up. For
some reason Pepsi does not work and no, I do not own stock in
Coke.
If you have some highly detailed pieces that the shot does not
seem to be getting into, there are smaller sizes of shot
available. 5mm long x 4mm diameter; 5mm long x 3mm diameter;
and we have even special ordered for some customers 5mm long x
2mm diameter. This shot is all very expensive though. Even the
standard 5x5mm shot is expensive - so be careful about losing
it.
I’m sorry for running off at the mouth! But I hope this has
helped you a little.
Best Regards,
Elaine Corwin
GESSWEIN CO INC USA
Tools, Equipment & Supplies for the Jewelry Industry
Telephone: 1-800-544-2043
Fax: 203-335-0300
http://www.gessweinco.com