My wife likes to compost. But finding an affordable and effective bin is hard. Over the years, she has used compost piles, store-bought bins, and bins I built for her. All of these had problems.
There are two ways to compost and if you are a person who only composts yard clippings then you are probably thinking "What's the big deal? Just throw the stuff in a pile and be done with it." But if you also compost kitchen scraps then you know this is where the problems begin. Kitchen scraps attract mice, rats, possums, skunks, and raccoons. This makes open bins a problem. Your neighbors will probably frown if you are increasing the local rat population. (Except for my rat-loving friend who shall not be named.)
Pets can be another problem with open bins. Our dogs have enjoyed many hours of digging through the compost looking for mice and lizards. And they have literally ripped apart plastic, store-bought bins while "hunting".
Open bins are an attractive option because they easily satisfy several requirements for composting: heat, ventilation, moisture, and occasional mixing of the compost. But in our experience they are too much trouble.
So in my opinion, a good compost bin should:
- Be black to absorb heat
- Have adequate ventilation
- Have adequate drainage
- Have a way to add water or better, collect water itself
- Allow for easy mixing of the compost
- Keep out critters and pets
One of the best bins I've seen is a black, cylindrical bin that lays on a stand so it can be turned. But the price approaches $100 and it's relatively small. That bin gave me the idea to build the bin in this instructable. My bin is made from an inexpensive trash can which I modified to meet my requirements. It's black, it has vent holes, its lid can be secured and collect water, it has a drain, and I can roll it on the ground to mix the compost.
Step 1: Parts
We don't need many parts for this compost bin. And these parts should be readily available at any home improvement store. I purchased all my parts at Lowe's, except for the ice chest drain plug which I got at Academy Sports.
- 1 - 32 gal. trash can
- 8 - #8-32 Nylon insert nuts (Stainless Steel)
- 8 - #8-32 x 3/4" Screws (Stainless Steel)
- 16 - 3/16" x 1" Washers (Stainless Steel)
- 4 - 4 3/4" Screen door pulls
- 1 - Ice chest drain plug
- 2 - 34" or 35" Rubber straps
I chose this particular trash can because it is cheap, it will be easy to modify, and the lid can be pushed in which will allow it to catch rain water. All of the fasteners are stainless steel to prevent rusting. The #8 screws just barely fit through the holes of the pulls. Make sure yours do the same and you won't use the screws that come with the pulls. Save them for another project. The rubber straps are just long enough to securely hold the trash can lid on without putting too much strain on the attachment points. I wouldn't use bungee cords because sunlight can cause them to deteriorate.
Here are the approximate prices of the parts:
- $16 - Trash can
- $2 - Nuts
- $2 - Screws
- $4 - Washers
- $8 - Handles
- $7 - Drain plug
- $6 - Rubber straps
Step 2: Tools
For this project you will be drilling holes, cutting off parts of the trash can, and tightening nuts. Here are the tools you will need:
- Phillips head bit
- 5/32" drill bit
- 1/4" drill bit
- 1" drill bit
- Phillips screw driver
- Adjustable wrench
- Utility knife
- Scissors or metal snips
I used a 1" Forstner bit to drill the hole for the drain plug. However, this bit can be expensive. You can also use a 1" paddle bit (aka spade bit) or cut out the hole with the utility knife.
Gratuitous plug for DeWALT Tools - I am highly satisfied with my DeWALT 20 volt drill and driver. The lithium batteries are a joy compared to Ni-Cad or Ni-MH batteries. They don't lose their charge during storage and 20 volts provides more than enough torque for most jobs.
Step 3: Attachment Points for Straps
Your compost can attract critters and pets. We need a way to secure the lid. The four screen door pulls will be attachment points for the rubber straps which hold the lid on.
I installed the pulls on the raised sections of the can which are next to the garbage can handles. The pulls are installed 5 3/4" from the top of the can. Mark the can 1" from the edge of the section and 5 3/4" from the top. This will be the location of the first hole for the pull. Center one hole of a pull over this mark, align the pull horizontally, and mark the location of the second hole. To make this easier, make the first hole using the 1/4" drill bit. Loosely attach one side of the pull to this hole putting the parts together according to the picture. Align the pull and mark the second hole. Then move the pull out of the way and drill the second hole. Finish by attaching the second side of the pull to the second hole.
Tighten the screws and nuts with the screw driver and the adjustable wrench. If you choose to use the drill to tighten the screws instead of the screw driver, use a lower torque setting so you don't over tighten the screws.
Step 4: Drain
You don't want your compost to be too moist. The ice chest drain plug lets us drain off excess water. Install the plug on one of the sections which has the garbage can handle. Drill a hole 3" from the bottom of the can in the center of the section. Use the 1" drill bit or utility knife to make the hole.
Install the plug as shown in the picture. The drain plug and its cap are installed from the outside of the can. The nut, washer, and gasket are installed on the inside of the can. Notice there is an error in the drawing on the package. The open ring of the cap has to be installed between the garbage can wall and the lip of the drain plug, otherwise it will simply fall off.
Step 5: Vent Holes
Your compost bin needs ventilation holes. The location and number of holes is not critical. However, the holes should be above the drain and I didn't want the holes so low that ants could find their way in.
The trash can I used has raised and recessed sections. I drilled three vent holes in the center of each section. On the raised sections, the holes are 13, 19, and 25 inches from the bottom of the can. On the recessed sections, they are 9, 17, and 23 inches from the bottom. Use the 5/32" drill bit for the holes.
To speed up the measuring, I made a guide stick with the location of the holes for the raised sections on one side and the recessed sections on the other.
Step 6: Lid
The trash can lid has supports on the underside to keep the lid from collapsing. Of course, we want the lid to collapse so it will act as a funnel which will catch rain water or allow us to add water with a hose. We need to remove the supports. Cut along the white lines shown in the pictures with a utility knife, scissors, or snips.
Now that the lid can collapse, we need holes in the center to let the water in. Use the 5/32" drill bit for the holes.
Instead of one bigger hole, I went with small holes to keep out mice and rats. It is possible they will try to chew their way in, but I haven't noticed this, yet. Another option is one bigger hole reinforced with galvanized metal mess. But, that means more parts and complication.
Step 7: Behold the Awesomeness!
And your compost bin is done!
I have built three of these and my wife seems to like them. We haven't had any issues with critters and our dog ignores them.
Testimonial from an actual customer:
"I have three of these bins and I think they will work very well. I haven't gotten any compost out of them yet as we've only had them a few months and I am not a faithful compost turner! However, I have great expectations. I have elevated them about 6 inches using leftover bricks. This lets me drain off the compost tea (excess water) into a bucket so I can use it to water plants with. To turn the compost I simply lift the bins off the platforms and roll them around the yard. If we have gotten a lot of rain I will leave them on their sides in the yard to drain more completely through the vent holes."