Picture of Double-Decker Drum Composter
Composting is easy and fun. Kitchen scraps, leaves and lawn clippings are allowed to decompose naturally and they become a healthy, nutrient-rich and beneficial soil for the garden.

In this instructable, I will show how I made a spinning double drum composter to make soil for my garden.

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Step 1: Making the frame

Picture of Making the frame
I decided against documenting every step with building the frame, mainly because it's a simple enough design.

The frame consists of 3 pressure treated 4x4's and 1 pressure treated 1x4, all eight feet long. One 4x4 was cut exactly in half and the 1x4 was cut into quarters - they were to become the 2 beams and 4 stakes.

I drilled pilot holes through the posts and into the beam and held them together with galvanized lag bolts. Each of the corners where the beam meets the post got corner braces and the top got flat braces. The braces are meant for extra support, since the barrels may become heavy. The space between the top beam and bottom beam was 3 feet.

I used a 2 inch hole saw to cut holes into sides of the posts so they can hold the poles later on.

Then, I used some exterior screws to fasten the stakes to the bottom of the posts. The entire frame gets cemented into the ground later and the 4 stakes offer additional support to the frame.

At the bottom of the posts and stakes, I drilled some screws partially into the wood to hold them into the cement better.

Step 2: Installing the frame

Picture of Installing the frame
After the frame was complete and I decided where it was going to go, I dug two trenches for the posts and stakes to go into.

Step 3: Installing the frame

Picture of Installing the frame
After I dug the holes and set the frame into place, I filled the holes with fast setting cement. Each hole took 6 bags (12 total - 60 lbs. each).

Once the barrels are made and full, they could get very heavy with the compost so the frame and concrete anchors must be strong. I feel as though the stakes and concrete will prevent the frame from leaning or moving much.

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pjgardens7 years ago
(removed by author or community request)
why is galvanized pipe a "no no"?
wfdixon sedona0073 months ago

metal has a zinc coating. Questions have been raised regarding the safety of zinc. The coating on these pipes may also have cadmium which is dangerous. (Do a search for toxic effects of zinc.)

iPodGuy (author)  pjgardens7 years ago
Why is that? What's wrong with it? Any sort of pole that is strong enough would work I guess.
There is an issue with food storage if it is acidic in galvanized vessels. There is also an issue with the lead-based solder used to hold together buckets, etc. as it can leach out and be absorbed by food. In your application though there is likely little contact with the pole and there is no solder involved.
is pvc okay?
iPodGuy (author)  vooodooo5 years ago
It needs to be strong if you plan to pack your drum full.
hey genius, this is a COMPOST BARREL!!! It doesnt matter about "food storage", and "acidic gavanized vessels"........ freakin genius
it does matter about food storage because most people put their compost on vegetables, which become food. as plants grow they have to adsorb nutrients from the soil, so whatever is in the soil will get into the plant. so i think this is an important, and i would like to know of an alternative if there happens to be one
iPodGuy (author)  arkbuchman5 years ago
The only idea I've got is PVC or ABS pipe, but it's surely not as strong as metal pipe.  Copper or cast iron probably isn't good because both will oxidize.
wfdixon3 months ago

I love this idea!

joeyisadog1 year ago

the quality of your composter is great. Looks very strong. When you move out of that house they'll make it a swing set with the framing that'll last for decades... :)

However, if those are oranges in your compost i recomend not composting them because the citric acid with throw-off your ph and could kill or inhibit good bacteria, etc.

enper1 year ago
hi iPodGuy,

this seems to be taken from your idea.
alftalavera2 years ago
Hello friends, I have my rotating compost barrel, say mechanically works acceptably, but beginning to have doubts about its effectiveness beyond being an ingenious and striking.
When green waste burial in a pit in the ground decomposition is very fast and the result has always been good, but this is more work to turn a barrel. With this method I find it hard to find plant debris after a week.
With the rotating barrel took 15 days and I have only a mixture of herbs and plant something muddy, clarified that the mixture contains dried leaves, ground black oak, and ready-made compost.
The barrel has a strainer at the bottom to drain the leachate and in the lateral walls having holes for ventilation.
I think I did my best to build my barrel, I am satisfied with its mechanical operation. Only one thing I do not like is that the tube that operates as an axis, is tangled grass and some like banana peels. If I had to build it again would prevent him having an axis atravezara surely try a bearing mechanism that would stick in the side walls of the barrel.
If anyone interested can share their experience with a barrel swivel I appreciate it, just as I can share all the details of my case.
P.S. If my English seems strange, just tell them you do not master the language, but I do my best. My email is
leander373 years ago
The number of holes seems excessive IMHO. I would be worried about compost drying out. When I build this, I'd think about cutting the number of holes in half. Any thoughts?
iPodGuy (author)  leander373 years ago
Definitely go with less. You can always drill more later if the compost is not breaking down properly.

Half of them clog anyway.
I guess that answers my question about the top one dripping on the bottom one.
Cestus2 years ago
What a popular post! How do you get the compost out of the top barrel? Seems like a silly question, but important! Do you use a shoot or slide to get it into wheel barrel?
I live in Rio de Janeiro, Brazil and have making compost by the University of California Method (making compost in 14 days) using only grass clippings (nitrogen) and leaves (carbon), with good results.
Did you make compost in your system using only Grass Clippings and Shredded Leaves?
In how many days the compost is ready for using?

Francisco Bolivar
Lorddrake3 years ago
when the barrel is filling up do you have any problem with distortion around the holes that the axle passes through on the barrels?

if so. would it help adding a support plate inside and out (say 6-8 inches square) so that the axle passes through ... plate | barrel wall | plate .. to help redistribute the load?
iPodGuy (author)  Lorddrake3 years ago
I never had problems with the axle holes distorting. I just went and looked at the bottom barrel (the one I use the most) and even though it's been four years since I published this instructable the axle holes have not warped or bent. They're smoother obviously because they've been rotated on the axle so many times, but it doesn't appear that they've grown any bigger.

55 gallon drums are really strong.

If you're really concerned with your barrels becoming too heavy and failing, you could always add some kind of plate as re-inforcement. If you have an extra drum, I bet you could cut out plastic reinforcement plates, or wood, metal, pvc... It's certainly not going to hurt the design.

Good luck!

modrod5 years ago
Great Instructable. Last year I expanded on the concept and made a three-barrel, rotating composter where each barrel spins independently and the entire unit rotates to make unloading more easy. I'm still perfecting it and have learned a few things: If an empty barrel ends up on top, it takes a big effort to rotate the two full barrels to the top. I'm thinking of some sort of crank device but with at least two of the barrels cooking at any one time, it's difficult to do that kind of work to the unit. Still works quite well.

I started with lots of air holes, which proved to be too many for our desert climate, so I filled most of them. The down side to that was that during our very wet winter (unusual) the compost batches got too wet and stopped cooking for a while. Now that it's dried out somewhat, everything seems to be working well again.
do you have plans for this anywhere on the web? I would love to build one
Not really, just some rough sketches I made based on the original, double decker Instructable and other ideas. The only differences between mine and the double are the main axle and spokes, which are welded to a small piece of tubing at the center.

Sorry I don't have more. I didn't take photos as I went along, so in order to do a Instructable correctly, I'd have to build another one. That isn't feasible at the moment.
modrod modrod3 years ago
Just a quick update on my knockoff. Yesterday, one of the individual barrel axles broke, due to being rusted. I didn't use galvanized to go through the inside of the moist barrels, just some steel tubing I had left over from other projects. It's the bottom barrel in the photo. I'm now in the process of replacing that one and the other two. Other than that, it still works great.

On the spinning issues, I've found that making sure all barrels are full, at some stage of compost, really helps when turning the whole thing.

rhodge-1 modrod4 years ago
Gear the main shaft with a Large gear and the drive gear (or two) from a gear speed reduced motor that is fairly cheap at about $50. that will turn those on a 1/3 hp or up to 1./2 hp with all full.
About a 10 to 1 ratio maybe?
I got one of those second hand for $10. Was 1/2hp.

modrod rhodge-14 years ago
Interesting idea but a little overkill for this application. I've found that my rotation problem goes away if I just keep all three barrels full. :)

I have discovered that iPodGuy's original design for the doors is better than what I did. The plastic doors, at least one of mine, has warped a bit and I'll have to reposition one of the locks in order to get it to seal better. Not a big deal...
rhodge-1 modrod4 years ago
For the doors warping; I had occasion to put steel strap around the plastic of one I made years ago and that stopped the plastic warping; used Pop Rivets with inside washers for that.
Maybe add slide screen locks at a couple of other points to spread the load to stop materials pressing outward too hard? What do you think?
modrod rhodge-14 years ago
That's probably a good idea on the steel strap. Thanks for that for future reference. I do have two slide locks per door and will either move the one that doesn't line up or add another as needed.
aje127 modrod4 years ago
Dude that is AWESOME. I have a huge yard that has a BIG veggie garden and then an insane landscape flower and fruit garden. I would be really interested in how you did this and if you fixed your rotating issue.
modrod aje1274 years ago
Nope, haven't addressed the rotating issue yet. I've just been man handling it. I did recently empty out one of the barrels and rotated everything around. Didn't seem so difficult this time, maybe because the bins weren't really overly wet at the time.
iPodGuy (author)  modrod4 years ago
That thing is nuts! Nice work!
Here is my take on the dual-barrel setup -- a side-by-side. I bolted a 1-1/4 flange on each end of the barrel (flat side out), with PVC pipe adapter screwed inside and PVC pipe running between them as a bushing, and short pieces on the outside as spacers. I ran a single 1" galvanized pipe through the posts and both barrels.

Allen Cham3 years ago
This is so neat! Ipod Guy, do you think its a good idea for me to put some super dry soil in it too so it fertilizes the soil? Did you need any earthworms or anything like that? and also, do you fill the whole barrel fully with compost or only half full? and is it hard for you to transfer the compost from the top bin to the ground since the lower barrel is in the way?

Sorry its like a whole barrage of question :) great job!
leander373 years ago
For an extra $25 or $30 I'd consider getting an extra drum and cutting a door that would be oversized as compared to the opening. This might alleviate fit/warp/sticking issues.
iPodGuy (author)  leander373 years ago
That's a mighty fine idea.
Layout7 years ago
My grandfather once made a similar design out of a metal drum. He cut the door out of a second drum and made it larger than the opening. That way you only need two hinges and a latch and the door still holds its shape. Plus it is much easier to open than 4 barrel locks. Great Instructable.
Metal is a good idea, but be careful about what was previously in the drum (oil? pesticides? bleach?), and also consider rust as a potential issue.
SGravel4 years ago
A PVC "sleeve" around any type of metal pipe would solve the problem of potentially leaching contaminants into the soil. It’s an extra step, but you’ll get the best results combining the two materials.
Oddly, PVC may be more "toxic' than any metal that might be used. Steel is predominantly Iron, which is generally beneficial in soils.
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