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
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
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
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
The small 10 inch is about $75 - 100 in the US. Larger units cost