How to Build a Hot Compost Tumbler

Hot composting is an accelerated compost technique. Hot composting intentionally mixes equal amounts of carbon and nitrogen to generate bacterial action and heat a compost pile's interior as high as 140 degrees Fahrenheit. Compost tumblers are labor saving devices to turn the compost. Without them, you have to turn a large pile by hand, usually with a pitchfork. Tumblers allow you to rotate a barrel on an axis to remix the compost.

Things You'll Need

• 55-gallon drum (metal or plastic)
• 6-foot length of 1 inch steel pipe, with two caps
• 5-foot length of 1 ½ inch PVC pipe
• 4 3-foot lengths of 2x4
• 2 2-foot lengths of 2x4
• 2 5-foot lengths of 2x4
• 2 4-foot lengths of 2x4
• 8-foot 2x4
• 2 ¾ inch outdoor wood screws
• Portable electric screwdriver
• Metal drill
• Angle grinder
• File
• 2 metal hinges with metal screws
• Small lock hasp
• Scrap metal sheet, 14 x14 inch
• Tin snips
• Small snaplink
• Hacksaw

Instructions

Tumbler Door

1. Cut a 1- foot square hole in the side of the barrel with the angle grinder. File off the burrs and sharp edges around the hole if you are using a metal barrel.

2. Trim a piece of scrap metal to a square 14 by 14 inches. Place the scrap metal sheet over the hole, with an equal margin all around. Mark hinge holes along one edge of the hole, and in your sheet metal. Drill the holes, and screw in the hinges. Your door should open and close over the opening in the barrel.

3. Mark and drill the hasp to the free-swinging side of the door, with the stationary portion of the hasp on mounted on the barrel. You should be able to close your door, close the hasp, and secure the hasp with the small snaplink.

The Cross Stand

1. Build a wooden frame using the 5-foot boards and the 2-foot boards. The boards will be framed with the 2-inch edges up. Screws go in through the face of one board, and through the end of the nest. Put three screws in each joint, ensuring the abutments are tight.

2. Center the 8-foot board on the rectangle frame lengthwise, with the ends overlapping equally at each end. Screw the long board in place

3. Place the ends of two 3-foot boards into the corners of the frame. The ends will be 2 feet apart. Screw each end into the frame with the other ends of the board crossing 6 inches from the high ends. They will look like a teepee. Mark the cross-point so you can replace the boards to screw them together. Unscrew the base, leaving your screws embedded in the legs. You will put them back into the same screw holes. Place the "teepee" on a firm surface, and join them at the cross-point with three screws coming in from each side. Stand the teepee up, and reattach the base into the frame.. Repeat this process to build the teepee for the other side.

4. Screw a 4-foot board into the cross joint on the outside of the teepee. Screw the other end into the 8-foot board that bisects the frame. Repeat this process on the other side. These 4-foot boards will both extend down and out from the cross-stands, like the legs of the letter A. They are supports for the cross-stands that will support the filled compost barrel.

The Axle

1. Drill a 1 ½-inch hole in each end of the barrel, dead-center. Using your door as access for your guide hand, pass the PVC pipe through the two holes. It will be tight, so tap it if you have to. Fit the PVC so that it extends equidistant from each end of the barrel.

2. Hold the barrel up between the cross-stands. If the PVC reaches either end of the cross stands, trim it off until it is just short of resting at each end.

3. Pass the steel pipe through the PVC, until it is equidistant on each end. Cap the pipe at each end. Set the ends of the metal pipe on the cross-stands.

References

• Mother Earth News: Compost Tumbling
• Brunswick Department of the Environment: Compost Containers

Resources

• United States Department of Agriculture: Composting