In all the discussions of carbon steel and stainless steel tumbling media,
I’m still unsure about the differences between Vibratory and Rotary
Tumblers? For burnish sterling silver, what are the pros and cons of
either or both systems? Thanks in advance! efw
Hi Edward & Brenda,
Rotary tumblers have rubber or plastic lined drums that lie on their sides
and literally roll on rollers. The medium and work pieces ride up the side
and cascade within the drum as it rolls. This action does not do a
particularly good job on hollowed out spaces and insides of rings.
Vibratory tumblers vibrate the medium and work pieces but the actual
container is not rolling. The hopper is often set up on springs to
accentuate the vibration. Generally, the hoppers are designed with rounded
bottoms which permit the medium to not only vibrate, but to also roll
within the hopper. You get a much better coverage on interior surfaces
because of the rolling action combined with the random vibration.
Personally, I think you get a more consistent treatment of the work pieces
with vibratory tumblers. Many of them can have their vibratory action
adjusted whereas most of the rotary tumblers are on or off (unless you buy
the expensive models that have high and low speed switches). Also, the
rotary tumblers basically rely on gravity and have a unidirectional
action, hence less random overall coverage. It’s been my experience that
vibratory tumblers take much less time than rotary tumblers. The other
significant difference is price. A relatively cheap (small 1 qt. drum model
with 4lb steel capacity for $74 or a double qt. model that handles 8lb
steel for $93 in Rio Grande catalog) rotary tumbler can handle steel shot
since the drum rolls on rollers turned by belts - not a very complex piece
of technology. You have to spend over $150 to get a vibratory tumbler that
is rated for steel shot (ie. Gy-Roc Model B with 8lb steel capacity for
$169 in Rio Grande catalog). As your load requirements increase, the
vibratory machines start to increase in price at a faster rate than the
rotary machines.
I usually prefinish my silver by using plastic quartz impregnated
pyramids. I then do any quick tripoli or bobbing as needed. Then I burnish
in stainless shot for about 2 hours, sometimes less. I have my AV-25
Raytech vibratory machine at a medium amplitude and I check every 20 to 30
minutes in the beginning, then more frequently later depending on the kind
of pieces I’m working on. Silver is pretty soft so if you have textures you
want to keep, you have to make sure that you don’t burnish them to
oblivion.
Hope this helps answer some of your questions.
Donna
Hi Edward,
A rotary tumbler is essentially a barrel laid on its’ side on 2 shafts. As
the shafts are turned, usually by an electric motor the barrel is turned
slowly (several rpm). The items to be polished (burnished) are placed in
the barrel with metal shot, abrasive material or some other polishing
media. With the ends of the barrel securely fixed in place the machine is
started & left to run for hours, days or weeks depending on the material
being polished & the media. Rocks usually take days or weeks, metal can be
done in hours.
The barrels are usually about 1/2 full of media & rocks/metal. When
running, the face of the load assumes the shape of hill with the material
in the top (aprox 1 inch) part of the hill sliding down to the bottom. It’s
while this sliding action is happening that the polishing takes place.
Vibratory tumblers are bowl shaped, with a center section similar to the
center of an angel food cake pan. The bowl is attached to a platform that
is separated from the base by a number of springs. The springs permit the
bowl (and anything else attached to the platform) to move independently of
the base.
A small motor with a weight attached to its output shaft is also attached
to the bottom of the platform. When the motor is running, the weight cause
it to be out of balance & vibrate. Because it’s firmly attached to the
platform the platform & everything attached to it vibrate at the same rate.
Consequently, everything in the bowl vibrates also. With assorted shapes of
steel shot, a little liquid & burnishing soap for lubrication, the shot
rotates around the circumference of the bowl & at the same time rotates
from the outside of the bowl to the center.
The act of burnishing metal relies on each of the shot striking the metal
like a little planishing hammer. Because all of the shot are moving,
relative to everything else in the bowl, the items being burnished are
struck thousands, maybe millions, of times. Each shot that strikes the item
makes it a little shinier & also a little harder. Think of it as work
hardening.
Because the all of the contents of the bowl are in motion all the time,
each piece is being polished/burnished 100% of the time, not just while
it’s in the part of the the barrel load that’s sliding from the top of the
barrel to the bottom. Typical time for polishing metal items is less than
an hour.
It should be pointed out though, neither tumbler will remove scratches or
other surface blemishes from metal. Blemishes of any kind must be removed
by sanding &/or buffing. If you put scratched items in a rotary or
vibratory tumbler, you’ll get shinny scratched items out.
The assorted shapes of shot, round, pointed, flying saucer, & french cut
green beans, do a good job of getting into most of the small spaces in
most items. Shot comes in both carbon & stainless steel. The carbon is the
less expensive (about $7 lb.), but more care is required to keep it clean &
free from rust. The stainless shot is about $12-15 a lb in the US. A small
vibratory tumbler (about a 10 inch bowl) requires at least 5 lb. of shot.
Vibratory tumblers come in several sizes from the 10 inch to much larger
industrial units.
The small 10 inch is about $75 - 100 in the US. Larger units cost
considerably more.
HTH
Dave
To the question of merits of vibratory versus rotary tumblers: for
burnishing silver, the fastest way with the least expensive machine is to
use a rotary tumbler and stainless steel. That presumes that you have
processed the appropriate abrasive steps prior to burnishing. Stainless
can be run in a vibratory tumbler but: you need more steel ($$$) to do the
job and a very expensive heavy, heavy duty tumbler. The rotary tumbler
only needs to have at least six flat sides, and be about 30% full of steel.
Dear Edwrd & Brenda,
When talking about media finishing I recommend both the vibratory system
as well as a barrel tumbler. We finish (in my shop) about 400 pieces a week
this way.
The vibratory system works the best as a two stage cut down cycle. I use
small pryamid shaped media. The black first for eight to ten hours (works
great overnight). Then the white for the same time. You must prep your
objects by removing large file marks or parting lines in the castings.
Your items come out with a soft matt finish. We use the Reytec as well as
the Rio solutions.
The stainsell steel shot is next for about six hours. This leaves the
sides and back bright and shiny needing at the most a light touch of rouge.
I florentine the backs of most of my models so they don’t need the same
polish as the fronts. The front is tripoli lapped and buffed, followed by
rouging with a ultra fine buff. The barrel tumbler is the only way to go
for steel shot. Unless you have an extra heavy duty vibratory system, the
motion doesn’t have enough strength to roll the shot. The shot is too heavy
to roll the same way the plastic media does. It just sits and goes around
in a circle with your objects at the bottom of the media. You want your
pieces to roll so all the surface is in contact with the media.
There is no contest between stainless and regular steel shot. All you need
for convincing is to find your regular steel shot rusted into a solid
ball. It will start to rust right away, and in humid areas it is a total
pain.You can save the stuff, but what a job! And storing it in the rust
inhibitor is too much work, along with constantly flushing the stuff down
the drain. The small mixed stainless sizes I have used (about twice a week)
is just as good as the day I bought it four years ago. I store it in the
same solution I tumble in. Just pop the items in when ready for the next
cycle and change it when done.
The most reasonablely prices vibratory tumble I have ever seen is sold by
the Midway Co. (phone #800-243-3220). They sell gun loading parts. You
burnish bullit casings the same way you tumble jewelry. The unit is under
$50.00. The only draw back is that the tumbling barrel is not a flow
through system which is absolutly necessary for these systems to work their
best. This is not a heavy duty unit but to begin with & try out it is
excellent. You can also contribute to the NRA on their order form if you
wish!
You can make your own flow through system by going to a restaurant and
seeing if they will give you a couple five gallon pickle barrells with the
covers. You then have to drill a hole in the side close to the botton of
one and put a drip valve in. The best kind of valve to use are plastic and
available through Consolidated Plastics (phone # 800-362-1000). These are
sealed in with a water proof calk or window glue. The second barrel is
used to catch the fluid as it exits the top barrel. A hose is led from the
flow through barrel to the catch barrel. The fluid is set to drip out one
drop at a time in a steady stream. Just make sure you see distinct
droplets. You save the sludge for refining.
Most small to medium rock tumblers work well, but you need to stay away
from the rubber barrels. Plastic barrels work the best and don’t react with
any of the solutions you mix with your shot. Some of the solutions eat the
rubber barrels. A steel barrel will rust just like the carbon shot so you
have that rust to deal with also.
If anyone wants to see all the various tumbling systems work, buy the Rio
Grande media finishing video. It is excellent. It shows all the systems,
large and small. It also tells how the process works with great video
shots. The actress talking on the video talks quite fast and doesn’t stress
the important parts, but you can watch the tape a few times to get the
whole picture.
Happy tumbling,
TR the Teacher & Student
The best deal I have found on vibratory tumblers is through a place called
Young Guns in Apex, NC. My friend, Cathy Holt turned me onto this. They
will sell you a Lyman Turbo Tumbler 1200 model (fairly big capacity) for
about $100.00 (includes shipping). It is also not autoflow, but I just
clean it out manually and it works fine for my work. I have four of them
and rotate my work through the different mediums. From blue cones,
porcelain balls, green stuff, and corn “meal” stuff (all through Rio).
The phone number is 919 (I think) 387-8393 and the guy I usually talk to,
Randy Young, is extremely nice and helpful. And, they don’t ask you to
sign up for the NRA. hope this helps. Wendy
I bought a Lyman 600 tumbler at a local gun shop last spring for about $69
and it was plenty big. I had plans for polishing some blue lace agate 25mm
hearts with some green corn husk stuff that came with it. The tumbler
worked great but the instructions that come with it are for polishing
bullet casings, not rocks. I gave up and never did get a polish on my blue
lace hearts.
Carol
Hi, I just ordered one of those little vibratory “tumblers” from Midwest
Supply - ON SALE for $39+ a little. It should be here this Fri. Midwest
is in Columbia, MO, so shipping to anywhere in the continental US isn’t
too bad.
I’ve been using Lortone barrel tumblers, but want the option of a true
vibrator-type, to I was delighted to find one at such a reasonable price
for experimenting. jmw
Judy M. Willingham, Consumer Pollution Prevention Specialist
237 Seaton Hall Kansas State University
Manhattan KS 66506
(785) 532-5418 FAX (785) 532-6944
Carol,
What state were your agate hearts in when you started trying to polish it?
Fresh cut or already pre-polished? If not pre-polished, you need to go
through the whole gamut of silicon carbide grits- 100, 240, 600, 1000,( or
some similar progression) then cerium oxide, tin oxide, iron oxide(
rouge) or whatever is your favorite for polishing. The corn husks just get
in the way until the final step.