Vibratory tumbling uses the same grit steps as rotary tumbling, including coarse grit (60/90 silicon carbide mesh), medium grit (120/220 silicon carbide mesh), fine grit (500 silicon carbide), pre-polish (optional), and polish (cerium or tin oxide). The difference is the amount of grit used. For example, in a 3lb. tumbler you would use 3 tablespoons of grit for a rotary machine whereas only one is used for the vibratory tumbler.
When filling the vibratory tumbler, fill the barrel about 7⁄8 to the brim. Most vibratory tumblers will have an exterior rotating movement in addition to vibrating side to side. The fullness or emptiness of the barrel will determine the speed of this movement. Almost every vibratory tumbler model needs to be pretty full in order to move properly.
The recommended amount water to use in the 3lb vibratory tumbler is about 1⁄2 cup if the stones are wet (from being freshly washed) or slightly more if they are placed into the barrel dry — rather than simply covering them, as is the case with a rotary tumbler. Most vibratory tumblers will complete each grit step in a day or two and take about three days for the polish cycle. To ensure enough action for each grit stage, we allow two days per grit cycle and three for polishing.
A vibratory tumbler attacks all surfaces of the stones equally because of its dual action: rotating and vibrating. This is especially effective on flat stones, such as slabs and cabs, but works well on rounded stones also. The only draw-back is that the vibratory tumbler’s dual action does not round rough stones as well as a rotary tumbler. The rotary tumbler attacks the high areas of each stone and is thus more affective at rounding stones. The ideal scenario is to employ a rotary tumbler for the coarse process and to use the vibratory tumbler for the last two grit cycles and polishing.