Below is a design for a "self-harvesting" vermi-compost bin.
The materials were sourced from recycled lumber and fencing. The only purchased item was a metal shank used for the "slicing" action that we will see later on.
• Skill saw/Jig saw
• about 16 ft. of (depending on how big you want it) 2x12's
• box of 1.5 inch screws
• 4 foot steel shank
• something that can bore a hole in metal...preferably fixed drill-press.
• 4 2x4's cut to 3 ft. each (legs)
• 2 2x4's for corner bracing + leg support
• Deer Fencing (12ft area - two sheets)
• Staple Gun
Step 1: Measure and Cut
Cut your 2x12's into 4- 4ft pieces + 4- 3ft pieces (3ft piece below)
Cut a rough estimate for your deer fencing (the bottom area of your 4X3 bin)...you will need to modify the fence as you apply it to allow the bin-legs to fit through.
Step 2: Brace Corners
Split some of your 2x4's to brace the corners of your freshly constructed bin skeleton.
This also allows your 2x4 legs something to sink into....
Step 3: Apply "Netting"
Overlap two pieces of your deer netting (staggered) to reduce the size of fencing holes. (this prevents your vermi-compost from falling through before you are ready to harvest it.
If you have a staple gun handy, secure the edges of the fencing against your wood frame...otherwise you can wait until step 5.
Step 4: Legs
In order for the vermi-compost to drop it needs to be raised. Cut your 2x4's to anywhere 2-4 ft. to allow for easy inspection of underlying vermi-compost.
Drill 2x4's into raised bracing + larger wood frame (angle). I choose to place the legs ontop of the fencing to ensure added support for the weight of the compost.
Step 5: Fencing Bracing
Add your lath now.
Drill a good number of screws (4-6 on the 4ft side / 3-4 on the 3ft side) to ensure strong support of fencing.
I decided to double up my layers on the 4ft side just in case.
Step 6: "Slider"
Next, use a skill saw (or, if you can't find one... a jig saw) and saw a half inch slit on the 2 inch mark of the bottom of your siding.
Do this on both sides until you can comfortably slide your metal shank from side of the bin to the other.
*note - make sure, if you're using the jig saw, to drill a hole first with a sizable drill bit in order to fit the jig into the wood in the first place. Ideally, use a skill saw.
Step 7: Touch-ups
Now that your "cutter" is in place - you can bore two holes on either side of the metal shank and attach a piece of rope in a loop over the wood frame so that one person can pull the loop of rope and slide the entire shank through.
use a thin piece of wood or whatever else you have lying around that will sufficiently block out sunlight. make sure to cut plenty of air holes in this thing (not too big...) so that it aids the bin in staying aerobic.
Place a tray underneath and fill it up with worms+organic material. It's a good idea to put down a good amount of paper shreddings until the compost has created enough aggregate so that it won't just fall through the fencing.
Once the bin starts to stack, the worms will constantly climb up towards fresh organic material and this is when you can start sliding the "slicer" and collect your fallen compost in your tray below.