Here's an instructable for creating your own wood framed, bottom access compost bin. It's worked great for our family for going on six years now, and it is fairly low maintenance.
Step 1: Materials List
Here's the list of materials needed:
(6) 2x4 x 8' Boards
(2) 2x6 x 8' Boards
(8) 1x4 x 8' Cedar Boards
(2-3) 1x6 x 8' Cedar Boards (Depending on how many front slats you want.)
(1) Half sheet of 3/4" Exterior Grade Plywood (48"x 48")
(1) Sheet of corregated plastic (26"x10')
(1) Roll of Tree Trunk Protection Netting (3' wide x 15' long)
(1) 6'-8' Length of Galvanized Utility Shelving Rail (Try to find a 1" x 1" double slot)
1 lb. Box of 3" Exterior Screws
1 lb. Box of 1-1/2" Exterior Screws
Drill w/ 9/64" and phillips head bits
Heavy duty staple gun with stainless steel staples
4' straight edge
Pencil and sharpie for marking cuts
Snips or heavy-duty scissors
Hacksaw with fine-toothed metal blade
Step 2: Lumber Cut List
Here a majority of the cuts needed for the project:
(4) 2x6 x 40-1/2" (Back supports)
(2) 2x4 x 40-1/2" (Bottom rails)
(4) 2x4 x 48" (Corner posts)
(16) 1x4 x 36" (Cedar-Side slats)
(3) 2x4 x 33" (Slide supports)
(1) 2x4 x 37-1/2" (Slide face)
(4-6) 1x6 x 37-3/8" (Cedar-Front slats)
Cut the half sheet of plywood to 36" wide by 48" tall. (You can have the home improvement store do this for you!)
Using the tape measure and carpenter's square, measure and cut the pieces above with your saw.
The last 2x4 will be marked and cut in Step #7 , for the slide support.
Step 3: Build the Back
Build the back of the bin by cutting down the corregated plastic sheet to give yourself 48" tall pieces. You have to lap the material (overlap one corregation) if it is not wide enough to span the entire 36". Staple the corregated sheet material to the plywood.
Using the 1-1/2" exterior screws, attach one of the 2x6 back supports at both the top and bottom of the plywood. Place the supports centered so that you have 1-1/2" on either side of the plywood on either side for attaching the sides of the bin. Use two screws on each side and place two additional screws roughly in the middle.
Place the other two support equally between the top and bottom supports in similar fashion.
The supports help with attaching the sides as well as providing extra support so the compost does not bow the back out (as much).
Step 4: Build the Sides
Start building the sides by taking two 2x4 x 48" corner posts and laying them on the ground parallel to each other (roughly 3' apart). Take one of the cedar side slats (1x4) postion it to the top and pre-drill and screw one screw in to hold it. On the other side, measure 1-1/2" from the side of the 2x4 and affix the cedar slat in similar fashion (one screw ) at that point.
Pre-drilling the cedar slats help prevent the slats from splitting when the screw goes through them! See the example photo.
Measure and mark 6" increments down both the 2x4 corner posts for locating the other cedar side slats. Once finished on both, take another 1x4 cedar slat and position it at the last mark on the corner posts and attach it in similar fashion to the top slat, also 1-1/2" from the same corner post side. Use only one screw at each point so that you can square the panel.
Using the 3-4-5 triangle rule, adjust your panel to measure as noted in the photo and your side panel is set to be square. Place a second screw in each of the attachment points to stabilize the panel - be careful not to jar the panel out of square!
Once you square the panel you can begin to place the infill slats. Use your marks to place the remaining slat for that side. Once place I step down gently to hold it in place to pre-drill and screw the slats in place. Two of the 1-1/2" exterior screws in each.
After completing one panel, construct the other panel as a mirror-image to that one by placing the slats 1-1/2" away from the opposite side 2x4 corner post.
Step 5: Layout and Attach Sides
Now that the back and side panels are constructed, lat them out to prep for attaching. The side panels should have the slats facing the inside and the 1-1/2" offset should be away from the back.
Tilt up the panels attach the side panels by screwing in the 3" exterior screws through the back supports into the corner post. Place two screws in each side of the back supports.
Step 6: Attach Bottom Rails
Turn the bin over to the bottom and attached the two 2x4 x 401/2" bottom rails tot he corner posts.
Now we're starting to look like a compost bin!
Staple the plastic netting to the top of the side panels with the heavy duty stapler and the stainles steel staples and cut it to length to the bottom. Use the stapler to affix the netting at about every other slat or about 12" - just to keep the netting close to the side panel.
Step 7: Construct the Slide Support
Take your last remaining 2x4 board and lay it against the back bottom rail and lift it to approximately 16" from the front bottom rail. Mark the 2x4 at the face of the corner post. Measure another 1-1/2" offset toward the back of the bin. Cut the 2x4 at the angle marked and stack the cut piece to cut an exact duplicate.
Attach the three slide supports between the two pieces just cut - one horizontal at approximately 12" from the end (to allow for better access to falling compost) and the remaining two supports vertically to better support the compost weight.
Test fit the slide support within the compost bin to position the slide face in location. Using the 3" exterior screws, fasten the slide face to the corner post (2 eace side).
Using the remaining corregated plastic sheeting, line the top of the slide with approximately 24" of the material, stapling with the stainless steel staples at roughly 8" on-center through the sheet to the supports. Make sure to line the leading edge of the sheet material with the back of the slide face (front of the slide support) so the compost can fall down the back.
Step 8: Construct the Front
Position your galvanized (or painted as shown here) shelving rail so that it rests on the top of the slide face. Mark a point approximately 1" below the top of the compost bin and cut the shelving rail with a hacksaw at that point. Repeat for the opposite side. Attach both of the rails with the 1-1/2" exterior screws.
Place the 1x6 cedar front slat in the channel as needed!
The retrieval area for the compost bin should look similar to the photo.
Load up with yard clippings and turn every once in awhile with a pitchfork to aerate.
Step 9: Composter Proliferation!
I've also given a demonstration of the building of this same instructable for my church's Green Fair and they ended up with two at their community plots! It's been a year and they still haven't even reached half capacity with scraps and coffee grounds. :)