Introduction: Rotating Bin Composter
This is a rotating /revolving bin composter also known as a batch composter.
Warning: Woodworking is inherently dangerous. You are using sharp tools some of them spinning at large RPM's. You need to be wearing eye protection at all times, hearing protection as needed and because you are going to be working on some very small pieces you must use a push stick. Niether I or Instructables bear any responsibility if you do something stupid, lose focus, act carelessly, or recklessly. Also the saw dust from pressure treated lumber may cause skin irritation and depending on your source of barrel the contents may be dangerous as well.
I strongly suggest that you only use food safe containers.
Step 1: Obtain Supplies
You will need the following items
1) Foods safe plastic barrel
2) Hinges. I used stockade hinges you may want to use a piano hinge. It is your choice. I was not willing to drill that many holes or use that many screws, washers and nuts.
3) 2 Barrel latches. Yes you will need two.
4) 1/4 -20 screws and nuts. I used about 100 to build two of these.
5) Washers- to match the screws you chose.
6) Lock washers- to match the screws you chose.
7) About 18" of sheet metal.
8) 2 2x4's 8 ft long.
9) 1 1x6 8 ft long.
10) Two handles with screws.
11) Approximately 4ft- 5 ft of 2 1/2 inch PVC pipe
12) Outdoor grade wood screws about 20 -30 I went with about 20 that were 2 1/2 inches and about 4 that were 3 inches.
13) Masking tape
Step 2: Tools
1) Drill motor
2) Drill bits 1/16th over the size of your screws. Spade bits/ speed bores are much better to use than conventional twist drills.
3) Hole saw Make sure it will go a bit larger than the diameter of your PVC.
4) Framing square and long strip of metal
5) Circular saw, Miter saw
6) Jig saw.
7) Screw drivers
8) Wrench or ratchet
9) Tin snips, Press brake/ metal shear.
12) 45 degree triangle
Step 3: Drawing the Door
Use the framing square and sharpie to draw the out line of the door.
There are two ribs that run around the circumference of the barrel. I put the narrow blade of the framing square on the out side of these and drew my lines parallel to them. I then used the large blade and made two lines at right angles to the first.
I your lines are not perfect that is okay a paper towel and some lacquer thinner will take the sharpie lines right off. don't ask how I know this,
I made mine 16 inches x 15 inches. This seemed like a good compromise I wanted an opening large enough to get things in and out, but not so large as it would distort the barrel.
Do not cut the door out yet
Step 4: Hinges and Latches
Your hinges will be straight if you used stockade hinges like I did you will want to give them a very gentle bend, just enough to match the curve of your barrel.
Take the masking tape and secure them over the line of your door.
Mark the holes using the sharpie.
Follow the same procedure for the barrel latches.
Remove the hinges and latches.
Using the drill bits that are 1/16th over the size screws you have drill out all the holes.
Drilling the holes before you cut the door will make it easier to line everything back up and you won't have to drill into plastic that is flexing on you.
You are going to want to clean up the holes with a razor knife or another drill bit. because it will have a plastic burr on it.
While you have your drill out drill a hole in each of the four corners of the door just inside of the line you drew.
Step 5: Cut Out the Door
Now very carefully using the hand jig saw insert it into one of the corner holes and cut out the door. Follow the line very carefully. You need to make sure that you don't go off the line to much because you may run into your hinge or latch holes.
Set the door aside for now.
Step 6: Drill Out the Ends
Take your framing square and a clamp and attach the metal strip to it so you have a 45 degree angle.
The barrels will have a mold seam that runs all the way around them. At the top and bottom lay the framing square on the circumference and make a mark across the mold seam. This will be very close to the center of the top and bottom.
I used the speed bore to start he hole and then used the hole saw to cut out the axle hole. You want this to be just a bit larger than your axle.
Be careful with this step. the drill will tend to grab.
Step 7: Metal Fins
My fins ended up being about 5" by about 18" and about 1/8" thick.
The purpose of these is to break up barrel contents as it moves around in the barrel to give you better aeration.
In the first picture you see that I lined up my holes to match the holes for my hinges. The first hinge will be attached using the farthest holes of the hinges. This will save you the trouble of drilling extra holes and wasting extra screws and washers.
After you mark, center punch, and drill your holes you will want to put a 90 degree bend in the fins about 1" in from the side.
Step 8: Attaching the Fins and Door.
As mentioned in the last step attach the first fin using the same screws etc.. as the farthest hinge hole and attach the hinge at the same time.
When that is done measure over the diameter of your barrel along opposite ends of the barrel in opposite directions. This will put your fins about 120 degrees apart at both end and the middle of the barrel. (see the fourth picture.
I used the framing square and the sharpie to draw the lines in the correct locations.
Line up your holes and drill them. I had to put a slight bend in the fins as my barrel ends had slight bevel on them. Attach these using the screws lock washer and 2 regular washers (One at the head end and the other at the nut end).
Once the fins are in place attach the door to the rest of the hinge holes.
Step 9: Attach Handle, Barrel Latchs, Areation Holes
If you were reasonably careful attaching the hinges the latches should line up pretty close. attach the handle after drilling the holes for it.
Next using the screws, washers, and lock washers attach the latches.
Don't worry if it is not a perfect fit the plastic is reasonably flexible and the handle will let you jockey it into position.
Once the latches are in place drill some aeration holes. I went with 9 holes about 5/8 ths inches in diameter. I drilled 3 sets of 3 120 degrees apart. In between the fins.
Step 10: Support Frame
I cut my 2 x 4's to 4 foot lengths.
I laid one on top of the other so the base was about 38" apart and the top was about 4" apart.
They crossed about 4" from the top.
There is nothing magic about the sizes. I set mine up at this height so that I could fill it easily from inside my carport, and when it was ripe I could get my wheel barrow underneath it to empty it out with out having to dig in to much.
I attached them to each other using two 2 1/2 inch screws from each side and a 3" screw in the center from each side.
I laid the second frame on top the first so that they would match and used the screws to attach those legs as well.
When the were done I measured the length of my barrel and cut the cross braces so they would be on the inside leg and give med about an inch of clearance on each side. I clamped the legs to the table top and pre-drilled the screw holes in the braces (see pictures 3 and 4).
I then clamped the braces in place and attached them with the wood screws.
You will need two cross braces to prevent racking.
Step 11: Finshed Barrel
Here is a finished view of the composter.
I built two of these at the same time as they are batch composters.
I have been told that it takes quite a bit of work when composting. You need to turn it over and it also takes quite a bit of time as well for the material to break down.
With these you add your material and simply spin the barrel.
While one barrel is breaking down you add material to the second and begin a new batch.
I am not sure of the length of fermentation time. I have been told that it depends on the material you put in, the temperature of the environment, and the wetness and humidity.
Time will tell.