Harbor Freight Tools 90979 operating instructions II. Before Use, III. General Use

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conditions around the tumbler are unchanged, and that the tumbler continues to operate in a safe location.

II.Before Use

1.Before the first use, and once a month following, put a few drops of oil on the Shaft Sleeve (14) bearings.

2.Check the Belt (37) tension. It must be kept as loose as possible without allowing it to slip on the Driving Pulley (35). Check before each use.

3.Make sure the exteriors of the Rubber Barrels (22) are clean so that they don’t slip on the rollers. Wipe them with a soapy cloth, then wipe them clean with a damp cloth, and dry them thoroughly. Do not use liquid cleaners or solvents.

4.Make sure that the Stops (6) are lightly touching both Barrel Lids (28). This will prevent the Barrel Lids from rubbing against the housing and will reduce friction. Check the stops periodically during operation.

Figure A

III. General Use

Note: These steps listed are for one barrel. Both barrels should be used together. If only one is to be “charged” (see step 2), use the other barrel on the machine as well to help keep the first in place. The barrels should be mounted with the Knurled Nuts (24) facing outward

1.To open one of the Rubber Barrels (22), remove the Knurled Nut (24) and the Washer (26). Next, remove the Barrel Lid (28)-see Figure A, right.

Note: It is imperative to load the Tumbler with the proper amount of materials, or the process will not be successful, and the motor could be damaged. An underloaded barrel will not lift rocks up the inner side walls allowing the cascading effect. Also, the abrasive material in an underloaded unit will tend to form a slurry and will not be effective. An overloaded Tumbler will not allow the rocks to cascade. Lastly, too much water will cause the abrasives to float and not do their job.

2.“Charging” a barrel means loading it. Charge your barrel from 1/2 to 3/4 full. More pointed or abrasive rocks or stones will require closer to 3/4 full, leaving a 1/2 full barrel when it comes time to polish.

Note: During tumbling, the stones will be reduced approximately 20% in size.

3.Choose stones that have a similar surface condition. They should have a mix of sizes ranging from small (3/16” to 3/8”) to large (3/4” to 1”). 25% of the stones should be in the smaller range. Split the remaining volume between medium sized (3/8” to 5/8”) and large sized (5/8” to 1”) stones.

4.For best results use a four step polish process. First, use a silicon carbide grain, 60-90 grit size. Second, use a fine silicon carbide grain, 220 grit or a little finer. Next, use a 600 grit silicon carbide grain or a pre-polish. Lastly, use a polish of Tin Oxide, Cerium

SKU 90979

For technical questions, please call 1-800-444-3353.

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Contents Dual Drum Rotary Tumbler For technical questions and replacement parts, please callSafety Warnings and Precautions SpecificationsRead all instructions before using this tool Save This ManualSKU For technical questions, please call How a Rotary Tumbler Works UnpackingOperation LocationIII. General Use II. Before UseIV-a. First Grind Approximate Amounts of Abrasive for each BarrelIV. Specific Instructions IV-c. Pre-polish IV-b. Second GrindIV-d. Polish IV-e. BurnishingTo Adjust Belt 37 Tension MaintenancePlease Read the Following Carefully Parts ListAssembly Diagram