Making a Rock Tumbler

• 1). Place a piece of baseboard or scrapboard on a work table. Measure the baseboard and mark the center of the wood with chalk. Choose a clean, sturdy plastic jar large enough to tumble the rocks of your choice. Inspect the jar for wear or cracks before positioning it in the center of the baseboard.
  
  
• 2). Position two sets of pulleys, or wheels with grooved rims in which a belt is inserted, in the center of the baseboard. The pulleys should be placed directly next to each other, so that the jar can rest between and above them. Screw the pulleys to the baseboard with metal brackets. Place the jar between the two pulleys, so that the pulleys support the jar. Turn the jar on its side and fit the pulley belts around the jar.
  
  
• 3). Position the rotary motor, or an electric motor that uses AC (alternating current), at the other end of the baseboard. Screw the motor to the baseboard with metal brackets.
  
  
• 4). Slip one end of the drive belt around the jar and attach the other end of the drive belt to the rotary motor. Fill the jar no more than three-fourths full of rocks. Use sand to fill the remaining space in the jar. Cover the jar opening with a lid. Be sure to tighten the lid securely before operating the rock tumbler.
  
  
• 5). Test the motor by turning it on. The jar should turn via the drive belt. Let the rocks tumble for 10 minutes. Then stop the motor and inspect the rocks. If the rock tumbler appears to be operating successfully, place the rocks back into the jar and let them tumble another 20 minutes. Then remove the rocks and clean them with soap and water. They should be tumbled enough to reveal a smooth, glossy finish.