I had an old rubber lined barrel lapidary tumbler that I inherited
finishing, I bought some shot and gave it a try. I did so after my
normal step of sanding all surfaces with a rubber abrasive wheel.
This is where I would normally go to either tripoli or Luxi blue on
a six inch wheel. I ran a piece for about 5 hours and really didn’t
see much change. I do think that I need more shot. I had no idea how
small a 3 pound pile of shot would be. I have done a lot of
finishing in a vibratory tumbler using ceramic cones. This works
well, but it isn’t worth doing unless I have a lot of work to run as
it wears out the cones regardless of how much work you tumble. I also
have a lot of burnishing compound and used it with the shot. I
normally polish my bracelets flat before I bend them. They would not
fit into the tumbler that I have without bending them first, so I
will likely buy a straight barrel tumbler long enough to fit a six in
long unbent bracelet. Before I do this, I guess that I need to know
what I might be doing wrong, how much shot I need (it is expensive),
how long to tumble in shot, what kind of results I can expect and
what prep work should be done prior to tumbling. I have always spent
a lot of time finishing my work and I am known for my finish. If I
can find a shortcut, that would be great, but I will not compromise
on my finish just to use a shortcut. Our recent discussion about
polishing safety has also prompted me to look into using shot. As
always, thanks. Rob
My experience with the tumbler as a finishing tool is considerable
but with very poor results. I use it mainly as a cleaner of new
pieces and to maintain a finish on already finished stock. But as a
final finish the results are not acceptable.
I have used stainless steel shot and burnishing compound in the past
and found inadequate results. I have used ceramic pyramids along
with flow through tumblers but no matter how long I tumbled stock I
still had to hand finish on the wheel.
At this stage of the game I wonder if I have higher expectations of
my finishes than my mass finishing equipment allows.
I too am looking for a more efficient finishing process but not at
the expense of my standards. But I am also willing to accept the
notion that I could be doing something wrong.
I use a lortone 3a tumbler with 1 pound od shot in it. I cover
thevshot with bwater and a amall squirt of dawn. Tumble
for 20 minutes with good results.
Robert, at the end of your msg you say you would not compromise your
finish of your metal. Ive been tumbling certain parts and certain
steps of mywork for the past 35 yrs. I do not accept the tumbler
step as a short cut or compromise. It is a step ive created since
the burnishing I get from thetumbler is impossible to get by hand.
There is no equal to hand finishing if your work is highly polished,
on the other hand if its highly textured then the burnishing step of
the tumbler is your friend. I use a 12lbs rotarytumbler, with 10lbs
of ss shot. very specific shapes for specific textures and 3d forms.
Most people useing a tumbler use it as “mass finishing” that idea
works well if one is well diciplined in a more scientific manner of
finnishing. formed 3d, textured pcs are much more siuted for
tumbling then large flat shapes. The smaller tumblers available to
the public will never give the mirror finishes you may be looking
for. the 12lbs, and the 40lbs tumblers are considered small by
industry standards, available to us. as tothe sanding marks, I
rubber wheel some of the edges and detail at 180 grtto 220 grt which
in a rubber wheel is a lot finer then actual sand paper as you know.
and the burnishing barely takes the lines out, the minute I hit
those areas with the polishing wheel they come up real quick. The
burnishing part also is mistake when people add too much compound or
too little. i use 920 powder, and to a 12lbs barrel I add 1tsp with
half the barrel filled with shot and 2 inches of water above that.
Half hour to one hour of burnishing. There are absolute over doing
the time in a tumbler, more time does not mean better results, at
all. There is a lot of info on tumbling in the mjsa archives,
vibratory always was recomended for flat surfaces, rotary for 3d.
The germans had even come up with a hybrid of the 2 for industry,
hope some of this info found its mark. Additionally never use house
hold soaps and what not as burnishing help. i have said this before,
the reason why industry has these soaps designed and produced for
specific reasons. My favorite is the 920 from rio for the black
rubber lined barrels, the 910 of the same is corrosive to black
rubber. if you are finicky about your work, be finicky about your
processes and equipment too. Best of luck
I have used ceramic pyramids along with flow through tumblers but
no matter how long I tumbled stock I still had to hand finish on
the wheel.
Its my understanding that ceramic pyramids are for cutting/grinding.
The polishing ceramic media from Rio is made specifically for
polishing Don. I have great results from that media particularly
with copper and brass.
Dep ending on the size of your barrel you probably just need more
shot, maybea lot more- and probably more variety to address all the
contours of your pieces.
Our classroom uses 5 pounds in a vibratory tumbler, and the chamber
is half filled or more. This allows most pieces to be covered or
mostly covered during the processing. The tumble motion moves the
piece around and all the shot taps the surface as the piece as it
moves along the chamber.
The objective is to have constant contact with the pieces that are
being processed. Think a mob of brownies with tiny hammers, gently
planishing the surface. Also having balls, saucers, angle cut rods
and pointy pins in your mixwill ensure that all areas of your piece
come in contact with the polishingmedia.
Use a bit of water and soap- just enough to make it feel wet, not
enough to make soup. This will carry away any debris from the
polished surfaces.
We use our Loretone tumble vibe 15 minutes to 2 hours, and get
fantastic results from the burnishing.
Jean pSmith,
Oxnard Gem & Mineral Society, Oxnard, CA
You mentioned Brownies with tiny hammers. That is one reason I do
use a tumbler that I think worked well. I tumbler to work harden
copper jewelry after soldering. That is success enough for me to
continue with the tumbler.
If you are known for your finish, stick with your old ways. IMHO, no
amount of tumbling, especially on forged or flat surfaces, will ever
come close to good hand finishing!
Robert - skipping the smoothing part will result in icky results
from the steel.
First you run your shaped bracelets in abrasive media, like you have
before. Then clean then well and run with burnishing compound and
steel for up to an hour.
Running them flat will have then nest in the steel, abrade each
other and generally get in the way of good finish. Running longer
than an hour will degrade the finish. Trying to harden them in the
shot only affects a micron layer of the surface. As you shape the
bracelets, prior to any tumbling, work harden them then.
A rock tumbler is ok for using shot - but: be sure the inside of the
barrel has “flats” not just round inside. Check the quality of the
rubber. What ever size of barrel, it should be filled at least 40%
with shot and your work. If you try to run too much work, it will
impinge on each other. The bracelets need to be able to move freely
inside the barrel.
The good news, the shot doesn’t wear out. Yes the abrasive wears
down, but it is sure cheaper than hand working the pieces.
I have finished literally hundreds of bracelets in my tumblers this
way, with sparkling results.
And - you might want to look at a newer model of rotary tumbler -
the acrylic barrels are much easier to close and open, don’t leak and
let you see what’s happening. This is the model I use -
Note that it requires a minimum of 5 pounds of shot and will run up
to 12 pounds of shot. Similar machines are available from most
jewelry supply houses. I especially like the variable speed and the
option to reverse direction automatically during the run.
If you are known for your finish, stick with your old ways. IMHO,
no amount of tumbling, especially on forged or flat surfaces, will
ever come close to good hand finishing!
You are probably right, but I have a lot of time now and the
resources to experiment and go where my curiosity leads me. Thanks.
Rob