Composter (Drum Style)

This composter rotates so that compost matter can breathe (which should also minimize odor) and break down a little faster. I created this prototype in about 2-3 hours. This project applies the fine art of meatball carpentry--emphasis on function NOT aesthetics. The materials should run about $10-$15. I don't know what the weight limit is for the compost matter.

UPDATE: There was some concern that the compost mass would be excessive (someone estimated 300 pounds). Currently, the cylinder is full with composting leaves and kitchen discards and it weighs roughly 35-50 pounds.

Step 1 Materials/Tools List

MATERIALS
2-Plywood 2' X 2' (This will be cut into a circle Radius= ???)
Fence wire 3' X 62 (Try to use a fine mesh--mine is ~1/4")
1--2 X 4 X 92-5/8"
1--1 X 4 X 48"
PVC 3/4" X ~35"
~49" Rebar
Nails, staples, glue

TOOLS
Measuring tape
Circular Saw
Sabre Saw
Drill
Hammer

NOTE: I will update this soon with more specific info

Comments

[javajunkie1976]

I've made similar compost tumblers yet when I go away, they still need to be turned.

So, what I did was to attach a slow RPM motor like a rotisserie motor controlled by a water sprinkler timer which also controlled a drip line that was placed over the tumbler. First the timer starts the motor, then after 5 seconds, the drip line is activated. After about 10 - 15 rotations, the drip line is cut off. The tumbler is continued for another 1/2 hour to make sure everything is mixed. Inside the tumbler I use 1x3 strips to act as "blades" (kind of like what's in your dryer.)

I usually set the timer for 1 activation per 3 days. I've gotten very good results this way.

[HenrikOlsen]

Quite late to comment I see, but I'd make the mesh as a spiral as in the attached doodle.

Turn the drum one way and the compost is mixed and aerated, turn the other and the drum is emptied.

[ERCBIENG]

 Clever!

[karo1039]

I don't think it has been brought up, but another modification you could do is to add something on the middle rod to make sure the pile gets mixed up, so the middle of the compost pile doesn't stay in the middle.

[hv3333]

There are simple tricks to mark out perfect circles, like using a nail, some string & a pencil to make a giant compass. An alternative might be to track down one of the plywood drums electrical cable (the larger scale stuff, not standard house wiring stuff) comes on - ready made circles with central holes. I was also wondering about putting the central axis slightly off-centre - if it was moved up very slightly (I'm thinking an inch at most) the drum would naturally settle in the same position the whole time. Another method might be to add a weight to the bottom. Just make sure you position the opening in the right place!

[ruthy nov]

To make a door you can simply leave your wire mesh longer about 2-3, staple as described, (leaving an opening), attach velcro to the flying end and to the secure end so you can close and open easily.
To keep your fingers from getting hurt by the wire, take a long enough plastic tube, cut a long cut and insert the wire mesh in it. It will hold nicely.
Thank you for all your wonderful projects!
old lady.

[soad17111]

this looks like a good idea. I am starting to get into saving the inverment. So i might use this.( or something close)

[TimBTodd]

environment*

[WalkaboutTigger]

I am going to recommend a slight modification. I live on the coast in California and in order to maintain appropriate temperatures within the pile, I wrap my bin with a blue or black poly tarp and secure it tightly to the drum with black rubber bungees. I added a gromet in the middle of the tarp to insert a thermometer but you need not do this if your needs to not extend to using a thermometer. The other advantage of the tarp is the prevention of leakage of fine particles (such as coffee grounds) during rotation. The tarp can also be completely removed and cleaned if necessary. Do not use a cloth tarp as they tend to compost very readily. Pre-cut round sections of plywood can be purchased from most home improvement stores. I also added 6-inch semi-pneumatic tires to my compost drum so I could move it around with my lawn tractor to the various areas of my property.

[jdlink]

WalkaboutTigger...good suggestion. Composts have different needs depending on your environs. For example, if it rains a lot, you may need to have a provision for limiting the moisture. If it is a dry climate, you may need to water the compost on a regular basis. As WT points out, you may need to provide for cold or hot conditions as well. My compost setup allows fine particles to fall thru. It would be a good idea to put a pan below composter to catch the particles...they are now ready for use.

[babybackribs]

suggestion- Wouldn't using clear plastic be more viable? Kind of like the greenhouse effect where the sunlight goes in but cannot escape, that should keep it good and warm no?

[WalkaboutTigger]

The challenges with using clear material are that clear material becomes opaque over time due to scratches and embedded debris, ages much more rapidly in the elements so it cracks and fractures, clear material that is IR transparent in one direction only is expensive, some of the microbes in compost piles experience significantly reduced reproduction in visible-spectrum light. Another 'attraction' to the black polyvinyl tarp material is that it can hide the less attractive aspects of the composting process so you don't have hide the compost drum, in limited space yards, when having friends or guests over - yes, vanity has its place!

[djsc]

I like this idea, could do it to any compost heap too.

[galadriel]

For a door, since it it wire, take a look at the doors on wire rabbit cages. The door itself is wire, it's held on with wire loops, and another bit of wire forms a locking latch. You could easily cut a door area out of your wire and make a wire dor to go over that cut out area.

[cindynsg]

I think I would use a plastic drum with the round plywood as support with a solid bar (like for weights) & PVC. The stand will work, provided the base is wide enough. At any rate, cut a flap out of the side of the drum, apply a piano hinge with support for for weight and a two slide bolts with supports behind them for added weight. If you want a screen, then you can make one to slide in when you open the flap door. Making a completely screened unit doesn't let the material compost because it lets too much air in. The idea is to get the material hot, sot the darker the barrel the better.

[pinoymale]

I just recently started learning about composting and this looks like an ideal project for my small apartment. Forgive my ignorance, but are you supposed to add soil to the above list of compostable material? How long will it take before it starts creating compost?

[jdlink]

pinoymale, I am not sure a compost system is a good idea in an apartment since it will attract various types of bugs. In some cases, you can store compostables in doors overnight (covered up) but any longer is risky. I don't add soil to my compost. I just harvested some compost that I started last year. It was really rich but as usual it is not completely digested. The compost drum may speed up the process but you may have to be very proactive...water compost when dry and turn it often. My guess is allow at least 4-6 months for the compost to break down but 1 year might be more realistic for black gold.

[Trebor1503]

If you leave it as a mesh all the way around then the smaller particles will fall out the bottom, which would be counterproductive to making compost. I would suggest lining the bottom half of the circumfrence with a solid, probably plastic sheeting would work fine, or plastic corrigated sign board. If you did that then you could lay a few 2x4 accross the underside to reinforce the barrel. I am inspired to try my own version 2.0 of this project.

[jdlink]

I had the same concern as nagutronsays where the wire mesh will sag under a lot of weight. So yesterday I set a 15 lb dumbell in the center of the drum. It held firm. I did the same for 25 and 35 lbs. It did ok. (I may muster up the courage and see if it can handle my 45, and maybe even the 55 lb dumbell.) I have no idea what the actual weight of the compost matter will be but my guess is that it will not exceed 50 lbs. I will upload photos with the dumbells soon.

[iwilltry]

I think that compost should be close to the same density as water (1000kg / m³). Soil is more dense than water, but compost is more aerated than soil. The volume of your cylinder with current dimensions is about 0.2 m³. If you filled it completely, that would be 200 kg (440 lb). 1/10th full (as nagutron suggested might be the limit) is already over 40 lb. Arguably the weight will be more evenly distributed than a dumbell, though. Not saying it will work or won't. Just posting some quick calculations. Good luck.

[jdlink]

First, compost is the final product. What is input is leaves, grass, coffee shells, etc...heterogeneous matter with a reasonable amount of air mixed in. The compost process digests this matter into a smaller denser mass. The drum should be filled originally to say 60-75% with this matter...(You should never fill it to 100%). It will reduce to maybe 35-45% full by the time the process has completed. We'll see and thanks for the input/calculation.

[Monkman]

I've been thinking of something similar, but for sifting soil. Spinning a drum sure beats shaking a screen back and forth. I like the use of the pipe to keep the ends apart. Thank you!

[servant74]

for the 'door', how about putting some plywood or old plastic sign board that can cover the hole (or a little wider, an inch or two). And use some inexpensive bungee cords (from a local dollar store?) to hold the 'door' in place during rotation. You can go fancier/different by putting buttons or screws (and leaving the heads standing proud) on one side of a board, and use wire ties or wire to loosely fit over them (so they can come off to open the device) and the other long side will be 'hinged'. To do a hinge, again wire tie or use 'bailing wire' to lace through holes near the edge (a half inch or so in from the edge of the 'door', to the wire cage. Make sure you have one 'hinge' every 3 to 6 inches for its full length. The opening side I would think to put at least one per foot that the door is long. And keep the opening slot kind of narrow (no more than a foot or so wide). Just some rambling thoughts.

[jdlink]

nagutron, I have considered this and for my prototype I expect to add cross rods as needed. As it is I have stapled the wire mesh to the round plywood at 2 inch intervals which may suffice. The compost matter will not be extremely dense (leaves, grass clippings, vegetable peels, coffee grounds) so the weight should not be excessive plus. Plus, it is counterproductive to fill the drum beyond 50-75%. Compost will drop thru when it is sufficiently fine (granular) to the ground or into a pan. But it is a prototype so I expect to learn what needs to be modified.

[nagutron]

This is a pretty cool idea, but I think that you'll need supports going all the way around for it to work. Kind of like bars on a cage, if the cylinder were turned vertical. They would be spaced six inches apart, maybe. Otherwise, I'm guessing the mesh will buckle pretty easily and you wouldn't be able to fill the composter more than a tenth full.

[ewilhelm]

You should add this to the Go Green Contest!