Step 1: Roughing. In the roughing cut the goal is to remove the undesirable outer portion of the agate. This usually takes the longest time and is not as critical as some of the other steps. With the Lot-O-Tumbler, use of a medium grit such as 180-220 (we use 120-220 grit) will do the fastest job of removing this outer material. (The use of a coarser grit such as 60-90 silicon carbide does not improve the performance.) The grit has to cling to the agate as it rotates in the barrel. Coarser grit tends to fall off the agate as it rolls and delays the roughing action. In order to grind away the rock, the grit must be in between the agates when they come together. If two rocks merely tumble together, there will be a buffing action but the outer portion will not be removed. Anything which keeps the agate from coming together on the silicon carbide grit will reduce the action of removing the undesirable rock.
The best action is achieved by wetting the rock just enough for the silicon carbide grit to cling to the agate as it tumbles. This is achieved by putting just enough water in the unit to insure that the agate is wet. If too much water is used, it will cushion the vibration and increase the roughing time. For a full barrel of agate in a variety of sizes, start with only the agate wet. If the agate cannot be rinsed in 12 hours add 1 capful (red tumbler cap) of water.
The Lot-O-Tumbler breaks down the 180-200 grit rather rapidly. Therefore, on the first two days of tumbling, there should be a fair amount of grit placed in the unit. The usual amount is about two tablespoons of silicon carbide. When the agates are washed daily mud and grit will be observed coming out. There should be a small amount of the original grit remaining to insure that the unit is grinding over the full period of time. On the last day of the 180-220 grit, it is best to use a light charge of silicon carbide so that all the grit will break down and the agate will start to polish. This insures that none of the coarse grit is carried over into the next polish.
As the grit breaks down and the excess material is removed from the agate, mud forms inside the barrel. This mud tends to reduce the action of the unit so regular removal is important. The barrel and agate should be washed every 12 hours if possible. In this washing, where the same grit is used, it is sufficient to simply fill the unit with water and swish it around. For a faster roughing the mud and excess material should be removed every 12 hours.
Some difficulty may be encountered in this first step if the lid pops off the unit. This is due to the generation of gas during tumbling. The problem can be reduced by punching a small hole in the top of the cap to allow the gas to escape without removing the lid. The normal grip of the lid is gas tight and should remain on the unit unless it is stretched by some means. In this case, a substitute lid can be used from such items as potato chip, dog food, or cat food cans.
Step 2: Start of Finishing Operation. In the first step of tumbling agate, a rough grinding action is used to remove the undesirable overburden of the agate. This rough grinding action produces a finish which is smooth and is dull in appearance. In order to obtain a bright luster the external surface of the agate must be smoothed so that no visible scratches are seen. This intermediate polish or 600 silicon carbide type is added (we use 500F Grit). This insures the breaking down of the grit and less difficulty of carry-over to the polish stages. After 24 hours of tumbling the agate should show an increase in luster.
In the Lot-O-Tumbler process, all that is necessary is the rinsing of the agate and dumping of all the old mud and grit. 1/2 teaspoon of the fine or 500F silicon carbide type is added. This insures the breaking down of the grit and less difficulty of carry-over to the polish stages. After 24 hours of tumbling the agate should show an increase in luster.
In order to polish materials such as Apache tears and quartz, it is necessary to cushion the action in the 600 grit (we use 500F) and polish of the tumbler. This cushioning is easy to do by adding more water with the grit to reduce the action and bring on a luster to these hard-to-tumble materials. The grit and agate are placed in the barrel and enough water is added to be visible through the top of the agates. This cushioning material is adequate to produce a fine finish on hard to tumble materials without the addition of any other materials such as tumbling pellets.
Step 3: Final or Polish Step (A separate barrel is recommended for this step). Before proceeding into this step all the material being tumbled should be removed from the tumbler barrel and inspected for any residue grit left from the previous step. The barrel, too, should be inspected to be sure that it is clean. If any of this grit is carried over it will continue to scratch the surface and prevent development of a high luster. With the proper amount of 500 grit there is less chance of carry over and less washing to be done.
This polishing operation is accomplished in the same ways as the previous steps except that a polishing compound such as Rapid Polish or Tin Oxide (We have used both Tin Oxide and our Aluminum Oxide Polish with good results) is added instead of the silicon carbide. Again only enough water to wet the agate is placed in the barrel. Then add about 1/2 teaspoon of polish – just enough to insure a light coating on the outside of the agate – indicating that enough polish has been added.
On the hard to polish materials such as Apache tears and quartz, the polish is introduced along with sufficient water to submerse the agate. This provides the cushioning action necessary to produce a shine on these materials. In some instances it may be desirable to operate the unit for more than one day to produce the desired finish. Usually one day is enough time, but longer times will not materially effect the agate and may produce a higher shine on hard to polish material but not on agate.
Special Operational Procedures
SLABS: Aluminum oxide pellets are recommended for slabs. To keep them apart and for faster grinding action. It is possible to tumble a full load of slabs in the lot O Tumbler by using the regular techniques described. Some difficulty is encountered if the slabs are not completely smooth, or are stepped by the saw cut. A longer tumbling time will remove the step. If the slabs do not seem to polish adequately, the difficulty is usually in the roughing of the slabs prior to polish. A fair amount of material must be removed from the surface the slab prior to polishing. This may involve considerably more time than the three days necessary for the round agate. More frequent washing is needed. Follow the normal instructions being used for cabochons below, after roughing to achieve a high luster in 4 days.
CABOCHONS OR FREE FORMS: The finishing of cabochons cab be completed in the Lot-O-Tumbler, normally if the cabochons have been taken from a 220 grit silicon wheel. Normally the amount of material removed in one day of tumbling in 220 grit is equivalent to the thickness of the pencil line used to mark the cab, and almost insignificant in the mounting of the cab. Cabochons finished with a tumbler are sometimes more desirable than those finished by hand because the tumbler polishes both front and back of the cab. Day 1: Put cabochons or performs that you want polished in barrel, fill with aluminum oxide pellets to 3/4 full, turn on machine and add aluminum oxide pellets to get best rotation. Add 1/2 of red cap of water, 1 1/2 tsp of 180-220 grit. Run for 24 hours. Wash out and put contents back into barrel. Day 2: Add 1/2 tsp of Fine Grit run for another 24 hours and wash out. Day 3: For the best results we have found that on the 3rd day, to add 1/2 tsp of 1000 or 1200 graded aluminum oxide grit. Run for another 24 hours then wash out. Day 4: 24 hours, add 1/2 tsp of polish. You should have a great polish if you follow this. To help you in cleaning out the tumbler, about 1 hour before you wash it out, add a few drops of liquid soap and a small amount of water. You will find the stones will wash off sparkling clean. Note: Use very little water in each step as to much water only washes the stones and slows the action of the tumbler.
APACHE TEARS: In the finishing of Apache tear, it is important to remember that they are delicate and chip easily. Care should be taken in the final finishing to prevent chipping. Tears are started in the same way as agate with 200 grit (we use 120-220 grit) and a small amount of water in the tumbler to assure fast removal of the extra material. This requires two to three days of tumbling. Wash away the excess material that has been removed and replace the grit after each day. After roughing in 200 grit, all of the tears should have a uniform surface. When the tears have been ground so that most of the chips in the tears have disappeared, the finishing operation can be started. The tears are placed in the barrel with enough water so that the water is visible down through the top of the tears, and 1/2 teaspoon of 600 grit (we use 500F grit) added to begin the polishing. After 18 hours the tears will begin to shine but will still look cloudy and non-transparent. At this point all evidence of grit is removed from the tears and the tumbler barrel. The tears are put back in the barrel with water to cover and one teaspoon of Rapid Polish 61 or tin oxide for polishing (we have used both Tin Oxide and our Aluminum Oxide Polish with good results). Two days is usually sufficient to produce a high luster on the tears. (Experimentation with a long period of time in the 600 grit will help the operator find the fastest time for polishing this material.
When tumbling tears it is recommended that one tear be removed daily to use as a comparison with the progress of the others. If the corners are shining while the flat portion is still cloudy, a longer period of tumbling is needed to improve appearance. If the corners are checking out and the flat portions are shiny, the action is too aggressive. It is important to keep the tumbler as full of tears a possible during the polishing operation in order to avoid the too aggressive action.
QUARTZ: All styles of what is normally referred to as quartz are handled in the same way as the Apache tears. The same method of roughing and polishing will produce excellent results.
TURQUOISE: Turquoise is an extremely soft material. Care must be taken in the roughing cut so that not too much material is removed. Start with a 200 grit, or better yet, plastic pellet with grit imbedded and check the operation periodically. Intervals of two or three hours are usually adequate in the roughing cut if turquoise. The finishing procedure is the same as for normal agate but the polish will be less than adequate. After normal polishing the unit can be filled with water on the polish cycle to obtain a more lustrous finish. A dry polish is then required to obtain the best results such as that used to polish silver to brass (walnut hulls and red rouge).
SMALL STONES: Small stones are processed in the same manner as other material of similar hardness. Sometimes the smaller stones will increase the weight of the tumbler and reduce the action. If the stones are all less than 1/4 inch in diameter, the load size should be reduced.
LARGE STONES: Normally anything that can be put thought the lid of the tumbler can be tumbled. If one or two large stones are tumbled, the remaining load should be of small size in order to obtain roper tumbling action. It is not advisable to tumble just two or three large stones by themselves. Large stones are handled in the same manner as other material of the same hardness. A mixture of sizes in a single load is suggested.
WARNING: If the material in the tumbler does not roll, difficulty will be encountered in all steps. A small load is one reason for lack of rolling. The other reason may be mechanical, lack of adequate anchor weight, broken springs or faulty motor.
Cerium oxide has not proved to be a good polish for use in the Lot-O-Tumbler
Plastic pellets are not recommended for a vibratory tumbler.
The unit as it is shipped from the factory is resonantly tuned to provide the maximum amplitude of vibration under a full load condition. The tuning is accomplished by the position of the tuning bar which is underneath the springs on the motor end of the unit. Moving the tuning bar changes the amplitude of vibration. It is not recommended that this be done until the operator has become familiar with the unit. With the tuning set for maximum vibration it is important to have a full load of agate. Anything less than the four pounds which the unit is designed to tumble will generate an action that is too aggressive and could result in damage to the unit or to the agate. Do not attempt to tumble small quantities of precious material without providing a filler to bring the weight close to four pounds. Use a tennis ball with a hole, set in barrel instead of the cap for a few stones. Be sure to add agate to the regular barrel.
Taken from Instruction booklet for the Lot-O-Tumbler
A Note to consider about 220 Volt Tumblers: Although these Motors work in the Continental United States they do require a special 220 volt receptacle which you may have to have installed to use them. Therefore they are not as convenient as the 110 volt variety which can be plugged into any common 110 volt receptacle.
The electrical power in many overseas countries is 220 Volt however and a tumbler for overseas shipments would probably require the 220 volt motor.