Madeleine's Compost Bin

Yes, there are plenty of compost bins on Instructables, but I wasn't satisfied with the looks of them and had specific lumber to use up from building a deck. These compost bins measure 3' by 3' by 2' tall. The front stiles are removable by sliding them up, making it easy to fork or shovel the compost out of the bins. The back stiles are screwed in place for stability. Other openings are screened with fiber glass mesh. Tops are hinged, each swings away from the center.

I built two bins so I can keep finished compost in one while the other is still working.

Step 1: The Design

I modeled the entire bin in Google SketchUp before cutting the first board. It was extremely useful to estimate materials and during construction as well. I kept the model on a laptop in the work area for easy reference. You can download Google SketchUp application for free at http://sketchup.google.com

I'm providing the .skp file in this Instructable. Free! as in free beer.  NOTE: after download, you must rename it with an .skp extension for SketchUp to recognize it.

Step 2: Gather Materials

The bins use dimensional lumber and standard hardware. Here are some rough numbers, but if you want a really accurate take off, you can use the SketchUp model

2 x 4, about 24 linear feet
2 x 8, about 35 to 40 linear feet
5/4 x 6" decking, about 40 linear feet
1 x 1, about 40 linear feet (I ripped these down from extra 5/4" decking, but you can buy them at big box)
3" deck screws, a small box
2 1/2" square drive, composite deck screws, a couple small boxes
6 galvanized tee hinges
36" wide fiber glass netting or hardware cloth, about 25 linear feet
Rubber spline (if you're using the netting), about 35 feet

The lumber I used is pressure treated with the less evil kind of micronized copper preservative. You would definitely not want to use lumber treated with the older chromated copper arsenate, which has been known to leach into the compost.

Step 3: Identify/borrow Tools

These are the major power tools involved

chop saw or miter saw
circular saw
drill
laptop PC

I also used a screw pocket jig which I bought at big box for this project. You have to clamp it down during use, so get a c-clamp of some kind if you do not already have one. I also used a special tool for installing fiber glass mesh in window screens.

Step 4: Cut Lumber to Size

With the exception of the spacer blocks used between the front and back stiles, all cuts are straight. I recommend cutting everything prior to assembly. Measure off of the digital model, then transfer to the wood and cut.

Step 5: Pre-drill Screw Pockets

All the joinery for this project is done with screw pockets, similar to furniture making. Pre-drill the screw pockets with the jig, making sure to use the c-clamp to keep it in place. The jig I bought came with a drill twist and metal collar used to set the depth. I used two screws on each side to join the 2 x 8 material, and one screw each side to join 2 x 4 material. These joints are solid, but you can add wood glue for insurance.

I also screwed and glued the spacers onto the stiles.

Step 6: Build Hinged Tops

The tops are made from 2 x 4 and use the same screw pocket technique. Because the tops will get a lot of handling, add the little diagonal bracing to make them really rigid. Bracing is left over pieces of 1 x 1.

Step 7: Construct Screens

Because I had fiber glass window screen material in the garage, I decided to take a chance and use it for this project. It may be too weak and get punctured or rot out, in which case I'll replace it with something else. If you're going to buy screen anyway, I recommend just getting some hardware mesh or chicken wire and stapling it into the frame.

To install the fiber glass mesh, I cut grooves into the framing with a circular saw, then used the screen tool and rubber spline to attach the mesh. Again, I recommend going with something sturdier if you're going to spend the money.

Step 8: Assemble Parts

Assembly is better done with two people because its difficult to get all these pieces together with only two hands. But once assembled, it will stand on its own while you put in the screws to attach the back stiles. Use regular longer deck screws, 3" or so, because they're going into the end grain of the stiles and can strip out easily.

Step 9: Install in Yard

Carry the assembled bin out to the site with two people. Cut 18" stakes to pound into the ground at the bottom front corners of the bin. These keep the side of the bins from spreading out and letting the stiles fall out.