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Tumble polishing


#1

I am just starting to do some production work. I have many small
pendants that need to be polished after casting. I am wondering what
the best method of tumble polishing can give me a head start or a nice
finish or both on the pieces. I want to take the casting “skin” off
the piece, without rounding edges, or destroying the design. I also
want them to finish with a bright polish. I am not expecting to do
this all with a tumbler. But what media in the tumbler does what? I
hear about corncob, stainless steel etc. Can anyone give me some
options, thoughts, feelings, on production finishing? I am also
wondering if I need to spend $100 on a tumbler from RIO or if I can go
to my local craft shop and spend $25. is there a difference besides
size? Thanks in advance. Joel Retzlaff


#2

Hi Joel,

     I am also wondering if I need to spend $100 on a tumbler from
RIO or if I can go to my local craft shop and spend $25.  is there a
difference besides size?

If I were you, I’d check a shooting sports (gun shop) store. Many of
them have vibratory tumblers that reloaders use to polish their brass
before reloading. These tumblers are the same as the ones jewelers
supplys sell. Only they’re priced lots lower. A friend just got one and
paid about $55 instead of the $90-100 jewelers supplys want.

Dave


#3

Joel; my vote is for the magnetic tumblers. Depending on the size and
design of the pieces choose from the several different sizes. I have a
production line that has a lot of surface detail that can’t be
polished off so I tumble it. I go straight to the red rouge from the
tumbler with great success. I sand the sprues to 600 before I tumble.
I also use the tumbler for very geometric castings that I finish with
a fine sanding disk and then tumble. It helps bring out the rough and
uneven spots so they are easier to finish down for polishing. Check
them out at your local jewelry supplier or show. Take a few casting
samples with you to see the results. Frank Goss


#4

Stay away from the $25.00 craft shop tumblers. The are extremely
noisy and have a very short life expectancy. The best of the rotary
tumblers is the Lortone. They have sizes from 1 1/2 lb up to 12 lb
sizes. All have rubber barrels. They last a life time and are
repairable if needed. The model 3A is a three pound, single barrel
tumbler that will hold about 2 or 3 cups of medial and material. When
I closed my store last year, it was selling at around $57.00. It is a
good size to start with. Check the garage sales for used ones. You
can sometimes pick them up for a couple bucks. If you go with a used
one though you will need to very completely clean out the barrel and
lid to remove any of the grit left from rock tumbling, otherwise you
might end up with scratches. You will then need a couple of pounds
of "Jewelers shot". Make sure that you get the mixed shot,
IE balls, pins, flying saucers, points, etc. You will also need some
"burnishing soap". This serves two purposes. First it is a
lubricant to help the shot "burnish" the surface of your
castings. Second, it prevents the shot from rusting. This is very
important. I always keep my shot in a burnishing soap solution to
prevent rust. I used to try to clean the shot after use and the
spread it to dry on a paper towel. I always got rust. When the shot
is kept in the soap, it stays bright. I have a large jar of soap with
shot in it that has been setting for over one year and the shot looks
just as it did when I put it into the jar. A good tip when mixing the
soap is to use distilled water. The soap tends to jell up after the
first use and I usually add a little water, the pour off some of the
liquid and then add a little more water. If you are doing a lot of
work, a vibrator type tumbler will be faster for you. The one I like
is the Gyroc. You can stack two tubs on it for additional volume.
Also the time is cut to about 20% of what is required in the rotary
tumblers. The cost though is over $100.00. The burnishing shot
does not remove any material so if you have a discolored casting, it
will still be discolored when you bring it out. The old adage,
garbage in–garbage out. The tumblers do speed up the process though.
Sterling seems to stay bright longer after tumbling also.
Don Rogers


#5

If you get stainless steel shot (such as from Rio Grande), you don’t
need to worry about the shot rusting.

Margaret