Introduction: The Best Triple Compost Bin

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Instructables has plans for several compost bins made from recycled products like garbage cans and pallets.  I've used a black plastic orb for composting, but it gets too heavy to roll around as it fills up with moist material.  I wanted to make a sturdy bin that was easier to use, would not compost itself, and could accommodate more waste, without spending too much on materials.  Wooden compost bin plans often call for pressure-treated lumber, but I don't like the idea of pesticides in the lumber leaching into my compost and soil.  So I decided to use recycled redwood, which I had in abundance from a play structure we built for our kids when they were young.  Redwood (west coast) or cedar are the best choice since they are rot-resistant, and will keep the garden organic and safe.

Although the triple bin uses lumber, the sides are made from wire hardware cloth, so this cuts down on the expense of using all wood.  You'll need a 3x9 foot space in your yard to accommodate this bin.  The large size will allow you to compost everything you've got--from garden trimmings to kitchen waste.  Ours is in the garden but not too many paces from the kitchen door, to make composting as convenient as possible.  The triple bin will also allow you to compost in stages, moving the contents from one bin to the next as the material breaks down.  With removable wooden slats in front, the compost is very accessible and easy to turn, stir or shovel to the next bin or the garden.

Step 1: Materials & Tools

DIVIDER FRAMES: Four 12-foot 2x4s (cut into eight 31-1/2-inch long pieces and eight 36-inch long pieces)
TOP AND BASES: Three 10-foot 2x4s (cut into three 9-foot pieces)
FRONT RUNNERS: One 12-foot 2x6 (cut into four 36-inch long pieces)
INSIDE RUNNERS: Two 10-foot 2x2s (cut into six 34-inch long pieces)
SLATS: Six 8-foot 1x6s (cut into 18 slats, each 31 1/4-inches long)

One 25-foot roll of 36-inch wide 1/2-inch hardware cloth (cut into four 37-inch lengths, and one 9-foot length)
2 lbs. 16d galvanized nails
One box poultry wire staples (about 250)
Twelve 1/2-inch carriage bolts, 4 inches long with washers and nuts
Two quarts clear shellac and paint brush
(Optional lid: exterior plywood cut into three 3 x 3-foot pieces and attached to the back with six hinges)

General wood-working tools are needed such as:
circular saw
tape measure
carpenter's square
socket wrench
wire cutters
drill with 1/2-inch bit
paint brush

Step 2: Divider Frames

  1. Butt-joint and nail two 31 1/2-inch pieces and two 36-inch pieces into a 35-inch x 36-inch square. Repeat, building three more frames.
  2. Fold back the cut edges on each piece of hardware cloth 1 inch.  Center each piece of hardware cloth on each frame.  Make sure the corners of each frame are square before stapling each screen tightly into place every 4 inches.  The wood-and-wire frames will be dividers for each section of the bin.

Step 3: Top and Bases

  1. Set two dividers on end with the 36-inch edges on the ground, 9 feet apart and parallel to one another. Position the other two dividers so that they are parallel to and evenly spaced between the end dividers and each other. (Each divider should be about 31 1/2 inches apart to accommodate the 31 1/4-inch long slats.)
  2. Place two 9-foot lengths of 2x4 across the tops of the dividers so that each is flush against the other edges.  Measure and mark on the 9-foot boards the center of each inside divider.
  3. Through each junction of board and divider, drill a 1/2-inch hole centered 1 inch from the edge.  Secure the boards with carriage bolts, but do not tighten yet.  Turn the unit right-side up so that the long boards are on the bottom.
  4. Attach the remaining 9-foot 2x4 to the back of the top by repeating the process used to attach the base boards.  Using a carpenter's square, make sure the bin is square, then tighten all the bolts securely.
  5. Fasten the 9-foot length of hardware cloth to the back side of the bin with staples every 4 inches around the outer and inner frames.

Step 4: Front and Inside Runners

  1. For the front runners, nail a 36-inch long 2x6 to the front of each outside divider and baseboard, making them flush on top (not as pictured in photo) and outside edges.  
  2. Center the remaining two 2x6 boards on the front of the inside dividers, flush with the top edge (not as pictured in photo) and overlapping about 1 inch on each side, and nail securely in place.
  3. For the inside runners, nail each 34-inch 2x2 to the insides of the dividers so that they are parallel to and 1 inch away from the front runners and flush with the top edge (as pictured).  This creates a 1-inch vertical slot on the inside of each divider, which allow you to easily slide the slats in and out.

Step 5: Slats

Insert the 1x6 boards into the vertical runner slots, up to six per bin. Paint all untreated wood with shellac.

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