Turning compost is the secret to quickly converting household organic trash into treasure in the form of loamy, nutrient-rich compost. But turning compost can be a messy, labor-intensive prospect. Barrel compost bins, which are also known as compost tumblers, are a compost bin design created to make the chore of turning compost faster and easier. As the barrel that holds the compost turns, the compost inside tumbles, much like laundry in a dryer. For kitchen scraps, wood chips and other clean compost, tumbler compost bins work very well.
Measure and mark the 2-inch by 4-inch board into four lengths that are 40 inches long to serve as frame uprights and four crosspieces measuring 29-and-3/4 inches. Cut the board into these lengths using a circular saw.
Measure and mark the 1-inch by 3-inch board into two pieces that are 40-and-5/8 inches long for cross braces, and four that are 23-and-3/4 inches long for corner braces. Cut the board into these lengths using a circular saw.
Measure and mark two circles out of the white pine plywood that are 7-and-1/2 inches in diameter and two circles that are 2-and-3/4 inches in diameter. Cut the circles from the pine with a jig saw. Drill a 1/2-inch hole in the center of each and glue a smaller circle to a larger circle with the center hole aligning to create two bearings.
Paint the inside of the 55-gallon drum with a coating of flat black paint.
Drill a 1/2-inch hole in the center of each end of the barrel.
Mark a 2-foot-by-2-foot square on one side of the barrel for the door. Hold your hinges against the marked door and trace around them to indicate where to drill holes for the fasteners. Hold the hasp against the side of the marked door opposite of the hinges and trace around it to indicate where to drill holes to attach the hasp to the door.
Drill holes for the hinge and hasp hardware into the attached door and the side of the barrel. Drill a hole in the corner of the door to give a saber saw a place to start cutting. Cut the door from the side of the barrel using the saber saw.
Turn the barrel over and drill four rows of 10 staggered, evenly spaced holes using the 1/4-inch drill bit to serve as ventilation for the barrel.
Form a lap joint notch in the end of each 29-and-3/4-inch long 2-inch by 4-inch board, and only one end of the boards that are 40 inches long, by marking with a pencil a groove that is 1 inch deep and 4 inches wide. Remove this notch with a jig saw. Adjoin the 40-inch long 2-inch by 4-inch uprights to the 29-and-3/4-inch long horizontal pieces with wood screws at the point where you removed the notch.
Cut a 1 inch thick, 3 inch wide groove 23 inches from the bottom of the frame into the side of each 40-inch upright. Fit the 1-inch by 3-inch cross braces into the grooves and screw them in place.
Affix the 1-inch by 3-inch corner braces to the outside of the uprights and cross braces with wood screws. Drill 1/2-inch holes into the exact center of the top horizontal pieces.
Slip the steel rod through the center of the drum. Pass the rod through the holes at each end of the drum. Slip a wooden disk onto each end of the drum with the larger disk end on the inside. Clamp the disks in place on each end using a stove bolt. Slip the rod through each hole in the top horizontal piece.