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Tumbling - barrels and Media


#1

I got a new Aubin rotary tumbler a few weeks ago and really love it,
as an upgrade from my old tumbler. For those who aren’t familiar, it
has a unique “diamond” shaped barrel (almost the shape of a typical
alcohol lamp) and it rotates around its central “point.” The barrel
is a translucent plastic.

I’ve always used stainless shot with my silver pieces, which is
primarily what I thought I’d use this tumbler for. But it’s been so
nice (and quiet!) that I thought I might try some of the dry
polishing media, like rouge-charged walnut shells.

My question . do I need to have a separate barrel for that type of
media? I’d assume it will leave a rouge residue on the inside of the
barrel, right? Will that rouge residue mess up my stainless shot? Or
will a simple wash/wipe with an ammonia/soap mixture clean the inside
sufficiently for use?

Many thanks for any advice!
Karen Goeller
@Karen_Goeller
Hand-crafted artisan jewelry


#2

Good question - I’ll be watching this thread! I’m fairly new to
the wonderful world of tumbling, so I can only contribute an
observation:

I have a cheap little Harbor Freight tumbler, which works
beautifully with stainless shot, but I also wanted to try a
final-finish media, so I ran a batch of cast pendants with some
green Rio Sunsheen media. After about 36 hours, I couldn’t really
see a marked improvement in the finish, so I emptied out and washed
the tumbler barrel and ran a new batch of pendants in the usual
soap, water, and shot. To my horror, the pendants came out
thoroughly coated with sticky black goo, which would not wash off
and had to be removed with Semichrome on a muslin buff. Of course,
this all happened right in the middle of a big rush order, so it was
a real pain in the tuchis.

After a good cleansing with the amazing flat Coke, the tumbler was
restored to its normal function and everything was coming out bright
and shiny again. All I can figure is that it maybe had something to
do with the barrel itself, which is made of heavy black rubber with
an appallingly phenolic smell that never quite wears off. I know
some of you fellow Orchidians must have the same tumbler; have you
encountered this weird problem?

I’ve been thinking of running a cycle with the final finish media in
a plastic Skippy jar, which just happens to fit the tumbler’s
dimensions perfectly. Any thoughts?

Cheers,
Jessee Smith
www.silverspotstudio.com


#3

Hello Jessee…

I've been thinking of running a cycle with the final finish media
in a plastic Skippy jar, which just happens to fit the tumbler's
dimensions perfectly.

Just one. If you do this, make sure you tape the lid to the jar very
securely, and then place the whole thing in a pan or something that
can catch the jar’s contents should the unthinkable actually happen.
I think that this could be a possible short-term solution, as long as
you can change the jar out a regular basis. With the constant
abrading action of the steel shot against plastic, you can expect
some etching on the plastic. Don’t know if this would throw any
"gunk" up on your jewelry or not.

Interesting idea. Let us know if it works.

Betty


#4

To answer the Skippy jar question – Rotary tumblers need to have
flat sides to work. Last time I checked, Skippy jars are round.
What ever you put inside will just slide and do little if any work.

For final finishing, I’d spend $60 and get a cheap vibratory
cartridge cleaning tumbler - Lyman type. It’s much faster with dry
media and you won’t be messing up your rotary one. Call your local
gunsmith or reloading supply store.

As to what happened, the dry media has a wax carrier which coated the
inside of your tumbler. The liquid used for steel has cleaners which
carefully removed some of the wax and detrius from the previous run.
It needed someplace to go and deposited on your silver. The coke
cleaner was exactly the right solution.

Judy Hoch, GG


#5
To answer the Skippy jar question -- Rotary tumblers need to have
flat sides to work.  Last time I checked, Skippy jars are round.
What ever you put inside will just slide and do little if any work.

Judy, I am puzzled by this observation. I use an old rotary rock
tumbler (“Thumler’s Tumbler, Model A,” 4-inch diameter), which has
a round interior, and with either ceramic or stainless steel media,
it works just fine for polishing. Is the rubber just a tad
"stickier" than the interior of the Skippy jar? Would lining the
Skippy with a thin sheet of rubber help? Just curious.

–Judy Bjorkman


#6

Dear Judy,

You bring up an interesting consideration…the one that suggests
that tumbler barrels work best when they have flat sides. I remember
reading an article in one of the lapidary magazines which was
written by a rockhound who was an engineer. He had conducted an
intensive trial and analysis of this subject and came to the
conclusion that barrels with smooth interiors were best. He also
suggested that the flat sided ones had a tendency to lift and drop
as opposed to a gentle cascading. As I have mentioned before, the
configuration of the barrel is just one of many factors. Loading,
buffering, viscosity and speed are other factors which must be
factored in. Theoretically, by altering one or more of the foregoing
factors one might be able to get excellent results from just about
any barrel.

I encountered an agate processor in Botswana who was processing
Botswana agate with the tilted barrel from a concrete truck.
Unfortunately he was turning out agates that were checkered with
surface fractures ( by the ton ) When I suggested that he remove the
internal baffles he was able to solve the problem…the baffles
were carrying the agates to the top of the barrel and dropping them
! (And, of course, the inside of the barrel was smooth.)

Ron Mills, Mills Gem Co. Los Osos, Ca.