Garden and yard: Build a labor-saving compost bin and never break your back turning compost again. (See the compost bin diagrams in the image gallery.)
How to Build a Labor-Saving Compost Bin
I work so hard in the garden that I don’t want to work
hard making compost as well. I’m sure you’ve seen the
traditional composter design with three separate bins.
You’re supposed to use a fork to turn the compost regularly
from one bin into another to aerate it. My alternative bin
design takes up less space in the garden and eliminates
that little bit of labor, so you can throw your back out
doing something more fun, like weeding.
Breaking It Down
The key to leaving your compost in one place is to get air
to the center of the pile. I use 2 inch ABS pipe that I drilled
full of holes. The sides of this bin have a 2-1/2 inch channel
for the pipe ends to ride in, leaving them open to draw in
air. I lined the channels with 1/2 inch hardware cloth, folded
to fit and stapled to the inside of the sides.
Most of the dimensions in this project are not critical; in
fact, you should build it according to the lumber you have
on hand. I had some rough redwood fence boards and a few
extra 2 by 4 studs; I cut the frame pegs from an old broom
handle. Redwood or cedar are the best choices for this
project because they’re the most rot-resistant. I won’t kid
you though; you’re making a box to hold decomposing
vegetable matter and wet dirt. Expect to replace it in 10
or 12 years, no matter what kind of wood you use.
Cutting It Up
Start by cutting all 16 side planks to the same length
— about 40 inches. You’re going to make two A sides and two
B sides as shown in the illustration. The basic difference
is that the battens on the B side have to extend past the
planks of the A side. You’ll also notice that the rabbets
on the ends of the battens are oriented so they fit
together to form a half lap joint.
Measure the width of four side planks lying side by side;
then add 6 inches to figure the length of your A side battens (2-1/2 inches for the channel, plus 1/4 inch between planks, plus 1-1/2 inch
rabbets at each end). Cut four 2 by 4s to the A length and
four that are 2 inches longer for the B side battens; then rip
them all into 2 by 2s (actual size 1-1/2 inches by 1-1/2 inches) so you
end up with eight of each.
The next step is to cut the 1-1/2 inches wide by 3/4 inches deep
rabbets on the ends of the battens. I used dado blades on
my radial arm saw and damped a stop block to the fence to
make them all the same. Now mark the centers of each rabbet
for the holes that fit over the pins.
Pull out four battens of each length to use as the top and
bottom frame members. Drill 5/8 inch holes in the ends for the
pins. Drill 3/4 inch holes in the other eight battens. Cut 4 inch
long pins from a broomstick or a 5/8 inch dowel and round over
the ends.
Putting It Together
To assemble the frames, use Elmer’s outdoor wood glue in
the rabbets of two A battens and two B battens and all over
the bottom half of the pins. Drive the pins in place and
check the assembly for square by measuring corner to
corner. If the measurements between diagonals are the same,
it’s square. I further reinforced this joint by driving a 1-3/4 inch screw into the pin at an angle that captures all three
pieces.
Now assemble the A sides by laying two of the shorter
battens on the floor with their rabbets facing the same
direction. Lay one side board across the end of the
battens, aligning it with the shoulder of the rabbet. Use a
framing square to help you position the battens 1-1/2 inches from
the ends of the board and also perpendicular to it.
Attach the board to the battens with 2 inch deck screws. Lay
another board at the opposite end of the battens and repeat
this procedure. Now position the two middle planks and
screw them to the battens.
To assemble the B sides you go through the same procedure,
except this time position the two outer planks 1 inches back from
the shoulder of the rabbets. After attaching the hardware
cloth to the channels, you’re ready to set this thing up.
Lay one frame on the ground with the pins up. Set the two B
sides in place with their rabbets up; then position the A
sides with their rabbets down. The planks fit down inside
the frame. Capture the sides with the top frame, fitting
its pins down into the batten holes.
Measure the distance between the channels of opposite sides
and cut the air pipes just a bit short so they don’t get
hung up on the hardware cloth. You’re going to need two
different lengths. I was only able to buy ABS pipe in 20 foot
lengths; you’ll need about 30 feet worth of air pipes. Cut an
equal number of both lengths for your compost bin, and then
drill ’em full of holes. If you have a drill press it goes
pretty fast. Cut the leftover pipe into 16 inch to 18 inch lengths
and use them as watering tubes next time you plant trees.
The last step is to cut a square of carpet scrap (easily
retrieved from an installer’s dumpster) to fit down inside
the bin. This will keep the smell down and help retain
moisture.
My Basic Compost Recipe
Throw in kitchen scraps; yard trimmings; manure from
rabbits, chickens, and horses (but none from meat eaters
such as dogs and cats); wood shavings, sawdust, and ashes
from your woodstove. Every couple of inches or so, lay one
of the air pipes across the pile and then throw on a layer
of dirt. Water your compost whenever you think of it
— but certainly whenever you rinse out the kitchen
scrap bucket.
