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Vibratory tumbler dry media for PMC

After having a couple of delicate PMC pieces mangled in my
traditional tumbler, I decided to pony up and try a vibratory
tumbler. However, being a poor artisan, I once again succumbed to
Harbor Freight when I saw the 5 lb capacity vibratory tumbler on
sale in their most recent catalog. Beneath the tumbler, they also
offer two and five pound bags of "rust-cutting resin abrasive media"
for removing rust from nuts and bolts. Not really what I was looking
for. But with no experience with this type of tumbler, I have no
idea which dry media would be best. I did a search and, as you might
imagine, came up with a ton of hits on everything from ceramic to
walnut shells to corn cob! And then I keep running into the
suggestion to “charge” the media (??).

Are there any PMC folks out there who can suggest a good media or
collection of media I should purchase (and where)… and how and with
what to “charge” it (I’m assuming this is akin to adding burnishing
fluid to a rotary tumbler?). Or a good book on PMC and vibratory
tumbling - again, no luck with a Google search. (I used to own Judy
Hoch’s book on Tumbling, but after the move a year and a half ago,
I’ve been unable to find the slim little volume). Also, I know how
to fill my rotary tumbler; but wonder how much media to put into this
monster. If all I’m adding to it are 10 to 15 small PMC pieces (or
fewer), do I fill the bowl? Half fill?

Additionally, as soon as I collect all the materials needed, I’m
hoping to try Maggie Bergman’s Photopolymer plate technique for
making PMC molds and wonder if a vibratory tumbler is the better way
to go to smooth out any hard to get at places that sand paper and
needle files could not reach.

Any illumination would be helpful and appreciated!

Thanks, folks


If your pieces got mangled in your rotary tumbler there are,
perhaps, only two reason that might have happened:

  1. your pieces are too thin walled or
  2. you had too much shot in the tumbler.

Try reducing the amount of shot in the tumbler and try again. I
don’t know how large your rotary tumbler is, so I can’t tell you
exactly how much shot to use, but, you don’t really need a lot
(perhaps, a handful of shot to a barrel whose volume is 8-10 cups
water). Rotaries are good old workhorses. Over 30 years of using
them, I’ve never worn one out. My husband found a small rock tumbler
at a flea market recently, two barrels, and the barrels are easier to
open than my old rotaries. Works very well tumbling my jewels and
only cost a few bucks. Also, your friend and mine, Harbor Freight
sells a cheap rotary that is also easy to open (I use one for
teaching PMC workshops).

I’ve not used a vibratory, so I’m not much help in that category.
However, I have a small magnetic tumbler which is one of the best
investments I’ve made. The shot is lightweight and the tumbling time
is reduced considerably. The polishing from this tumbler does get
into the crevices that deep- and fine-textured metal requires,
especially metal clay right out of the kiln. A Mag. tumbler is worth
the expense in the long run (and the short run). I bought mine from
Rio, but other suppliers have them, too. Contact me via my email or
phone and I’ll give you model number, etc., if you want.

Linda Kaye-Moses

I use several different media for my vibratory tumblers and silver or
metal clay pieces. Although I usually will tumble my metal clay items
in my rotary tumbler (doesn’t take as long a time and gives a nice
polish). If you’re concerned about small areas, you’ll need small
media. I suggest that you check out Rio Grande’s catalog on tumbling
media. They have a lot of explanation for the various media and a
good selection of choices. Have fun with the PPP technique.

BBR - Sandi Graves, Beadin’ Up A Storm
Stormcloud Trading Co
"Beads, Leather and Metalworking Supplies"
St Paul, Minnesota (USA)

I use blue plastic media with quartz embedded in it, from Rio
Grande, and stainless steel shot for a final shine. You want to fill
the bowl about 1/2 full of most media, because the weight of all the
media is what creates most of the grinding action on the bottom of
the load. For steel shot. I use less, due to its inherent weight (and
cost!). I run these media with appropriate soap solutions, also from
Rio. The plastic with quartz in it does not have to be charged with
an abrasive powder; it’s already in there. Most people probably use
at least 2 different grades of plastic media. for the finest shine. I
get by with one, for my work.


Karan - Let me try to answer your questions -

The rust cutting media on harbor freight appears to be a lightweight
plastic media very similar to that sold by Rio and others. The media
I know is gentle on work pieces. Since you bought a five-pound
tumbler, you need five pounds of media. Fill the bowl 90 percent
full, and then add your work pieces. The volume of media is required
to make the tumbler produce its torroidal motion. Using just a bit of
media will result in having the pieces just jiggle, not clean.

IMHO, I would purchase media intended for your use. I don’t know
what kind of abrasive is in the harbor freight media and it really
could do damage to PMC since it is intended for use on heavy metal
parts. Go to any of the jewelry suppliers and purchase a five-pound
bag of their lightweight plastic media. The pyramid shape works well
with PMC textures. It will smooth your work but will retain all your
textures. Use it with water and a deburring compound mixed to
specification. This media used dry will leave gobs of junk in your
work. Even though this is a dry tumbler, you can run it wet. It just
isn’t a flow thru process. I would start out trying a two hour cycle,
checking your work for your desired finish, and repeating up to
three more times if necessary.

Dry media is used in a second step to polish the PMC. The choices of
dry media are myriad. I tend to use wood chips charged with
simichrome or chrome oxide. This is similar to charging your buff
with rouge, just something to make the media work properly. You can
purchase several kinds of dry media already charged. A good example
is the green buff sold by Rio.

And last, my book Tumble Finishing for Handmade Jewelry is available
from most of the Orchid jewelry supply sponsors.

Judy Hoch