My friend Ryan gave me two barrels, a fifty gallon and a thirty gallon. I turned the fifty gallon barrel into a rain barrel and decided the best use for the thirty gallon was a new compost bin.
I have been composting for a while now but my system has been crude and very, very slow. Since my compost mostly just sat in two twenty gallon plastic garbage cans the process was more anearobic than aerobic because it quickly became difficult to impossible to mix things up with any efficiency. The plan for the new bin was to make it so the compost could be easily turned by simply rotating or tumbling the barrel, and thus its contents. I suspect the results will be compost is less than a third of the time with better consistency and texture.
I wanted to make the project as inexpensively as possible and tried to rely on materials I had around the house. One thing I want to make clear is that this was not an art project or something for display at a finish carpentry show or anything like that. It's meant to be strictly functional and so a lot of my cuts and techniques would probably be scoffed at by people who are actually handy or who consider themselves craftspersons!
My first step was to check out Instructables.com for some ideas. I looked at a bunch of plans and discussed options with Ryan and thought about it for a while. Then I took stock of what I had on hand and got to work. I took some scrap 2X4s and a piece of particle board that I had and used that for my rack frame. That project kind of evolved as it went because I realized it was not going to be sturdy enough to hold a thirty gallon barrel full of wet plant waste. In order to add support I took a length of half inch copper pipe that was in the garage and cut two pieces from that, flattened the ends, drilled holes into the ends, and screwed one to each side.
With the rack finished I went to work on the barrel. One thing I did that no one mentioned on the other projects was to mark out my door and then mark all of the holes for the hardware and drilling those before cutting out the door. That made the drilling much simpler because the surface was more sturdy and I didn't have to worry about trying to line up the latch slots while trying to holding a loose plastic door in place.
It would be easy enough to cut the door out with a jigsaw, but I just used a Dremel-type tool with a cutting wheel on it. It worked like a charm and cut through the plastic easily--though I ended up using two cutting wheels to do it. Once the door was cut I put all of the hardware on--hinges (thanks again, Ryan!), latches, etc. For a handle I drilled a hole in the door and fed a length of old inner tube through it and knotted it on the back side.
For drainage and aeration I used a quarter inch bit and drilled holes all around the barrel at about four inch intervals. Again, I didn't measure this out or anything like that. I just sort of eyeballed them and went for it. They are clearly not spaced perfectly, but they will more than do the job.
With the sides of the main barrel complete, it was time to do the ends. I cut two holes in the ends with a hole saw attached to the drill. The idea is to run a length of pipe (also from Ryan's yard) through the hole so that the barrel can rotate around the pipe. I wanted to add some extra support for the pipe so, like others have shown on the net, I cut two pieces from some wood I had and drilled holes through them as well. As you can see from the photos, these are far from perfect circles! In order to more evenly distribute the load across the ends of the barrel, I put five bolts through each end.
Once everything was put together I figured I should pretty it up some so I broke out the paint. I bought black spray paint for the barrel that is meant for use on plastic, Krylon Fusion. It works great but probably poisoned everything in a one mile radius. I wanted the barrel black so that it will help generate heat within the barrel. I had some green paint in the garage that I used for the rack.
I set it up and transfered all the stuff from my "current" compost barrel and gave it a few turns. Everything seems to work great!
