Make a Tumbling Composter

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About: Interested in electronics and workshop DIY

Did you know that over 1/3 of the food in the world is wasted? Or that half of the fruit and vegetables produced are wasted? (According to https://www.ozharvest.org/what-we-do/environment-f...

Obviously there are things that we should be doing to reduce food waste, like ensuring that we only buy what we need and planning out meals. I encourage you to do these things, but its inevitable that there will be parts of fruits and vegetables that we don't use. You can harness these scraps and left overs to help grow your own food or even just give nutrients to your garden. Enter the world of composting.

The advantages of making your composter are;

- Save money

- Design to your needs/capacity

- Re-use materials to make the composter

- Interesting project and having pride in something you built yourself

Step 1: Materials and Tools Required

Making your own tumbling composter is relatively easy and only requires a few basic tools and supplies. You'll need some or all of the following tools depending on what materials you have available;

  1. Hand saw/drop saw (for cutting wood to size)
  2. Hack saw (if required to cut your metal pole to size)
  3. G-Clamps
  4. Spirit level
  5. Cordless or Corded Drill with
  6. A drill bit a bit smaller than the diameter of your screws and Philips head bit to suit the screws you choose
  7. Spanner/socket to suit your bolts
  8. 2x hole saws for your drill; one to suit the size of your metal pole and the other about 2cm in diameter
  9. Dremel with plastic cutting disk
  10. Hobby knife or sandpaper
  11. Tape measure
  12. Drill bit about 5mm in diameter [optional]

The materials you'll require are;

  1. 55 gallon/200 litre plastic drum or a smaller drum depending on your needs. I got mine from a flower wholesaler for $22 (Australian). Its important to check the drum is food certified! The last thing you want to be putting on your home grown food is industrial chemicals...
  2. Sturdy metal pole about 30cm (10 inches) longer than the length of your drum
  3. 4x lengths of 4x2 wood just longer than your drum. Two of these lengths will be cut in half.
  4. About 30 self taping screws
  5. 2x M10 (or similar) bolts a bit longer than two of the bits of 2x4 put together (approximately 10cm)
  6. Two butt hinges about 7cm in length
  7. One or two bolt latches
  8. Length of plywood about 50cm x 10cm
  9. Paint or something to coat your wood in to protect it
  10. Two split pins or 5cm lengths of thin metal rod [optional]

Step 2: Prepare the Drum and Frame

First thing to do is to wash your plastic drum with dishwashing liquid and give it a good rinse. Then you want to find the centre of the drum on the bottom and on the lid and use the hole saw to cut holes so that your metal pole will slide through both ends.

Cut two of the lengths of 2x4 in half. Next form a sort of a X with these bits of wood so that you have a small crossover at the top and clamp them in place. Now you can lift the drum up onto these X's of wood so that the small crossover section is facing upwards. This is to check your frame is going to have enough height so the drum is lifted off the ground. Once your happy with the angles, use your spirit level to mark a line parallel to the ground on the lower bits of the wood.

Leave the clamps in place while you drill a hole in the centre of the X's of wood for your bolt to go through. After you put the bolt and nut on it, drill a hole a few centimetres away from the bolt hole with the drill bit thats just smaller than your screws. Put one of the screws in the wood. This screw is to stop the frame from rotating. Use the drop saw to cut the X's of wood along the line thats parallel with the ground. This will make sure your frame sits flat on the ground.

Mock up your frame so that the wooden X's are about an inch wider than the plastic drum, ensuring the drum can rotate freely. Take the other two pieces of 2x4 wood and put them into position so they sit on the inside of the wooden X's and will support the frame. Make sure they aren't too close to the drum to prevent it from rotating. Once in position, drill holes and put in screws. Add further screws as required to ensure everything is solid and won't move.

Step 3: Cut Out the Compost Door

Work out how big you want the door to the composter. Keep in mind that once your organic matter has been sufficiently composted, you may want to use a shovel to get it out.

Before you mark out the size you want your door, spin the drum a few times to find out where it comes to a stop. Use this as a guide for where to cut the door. Mark out the door and use the Dremel to cut it out completely. Smooth out any rough edges with a hobby knife or with sand paper. Secure the hinges on the upper part of the door making sure they are both level and don't work against each other. Secure the hinges to the drum using screws. You might want to cut the excess of the screws off with your Dremel so that it doesn't catch on anything.

Cut the pieces of plywood up so you have 4 squares about 10cm x 10cm (3 inchs x 3 inchs). Secure these squares with screws on the inside of the drum on the left, right and bottom sides of the door opening. These bits of wood prevent your door from going inside the composter and also give the door some rigidity.

Close the door and fit your bolt latches. I only had to use one, but some people prefer to fit two to make sure the door is secured when you rotate your drum and the contents don't spill out.

Step 4: Finishing Touches

Its optional to drill a small hole through each side of the metal pole about 5cm from where it comes out of the drum. This is to put a split pin/small length of metal rod through the metal pole which will prevent the pole from sliding through the drum. This is generally only required if the composter is going to be put on a slope. Alternatively just be careful when you rotate the drum and adjust it if its sliding in one direction to save you putting a pin in the metal pole.

Use your drill and 2cm hole saw to drill rows of holes in the barrel. The holes were about 10cm apart and I put them around the outer edges of the drum, but that was mainly to stop the liquid from draining out. The micro-organisms that break down the compost are just like you and I in that they need oxygen to survive. These holes allow the drum to breathe and will speed up the composting process.

The last step is to paint the wooden frame with paint or something else that's going to protect it from the elements.

Step 5: Composting Tips and Tricks

I hope you enjoyed building your tumbling composter. Enjoy having a use for those kitchen scraps you have preparing meals :)

Here's a few tips I picked up that will ensure you have a smooth composting experience!

  • Tumble your compost once a day to help circulate oxygen through the pile.
  • Keep a small ice cream container in the kitchen for your scraps and empty into the compost as required. Saves you multiple trips!
  • You can generally compost any fruits, vegetables or gardening cuttings, but DON'T add meat or dairy to your compost as these throw out the balance.
  • Start your composting by adding a small pot plant worth of rich soil. Soil contains all of the micro-organisms that help to break down organic material and adding it at the start ensures you give your compost a "kick start"
  • Place your compost in an area that is warm, but out of direct sun. The organisms will produce heat during breaking down your food scraps and placing it in a warm position helps to speed the process up.
  • Make sure you balance the moisture levels. Unless you are only composting water rich foods, you might have to add some water from time to time. Generally a good rule of thumb is to add the same water by weight as the scraps you are putting into the compost. You want to the "pile" to be moist, but not dripping wet. If your pile is getting too wet then add some saw dust or newspaper to dry it out.
  • Use excess water in your compost bin as a liquid fertiliser. It's called compost "tea" and is very high in stuff that your plants love!

Thanks for reading and if you have any suggestions to improve the design please feel free to comment.

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    10 Discussions

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    ericCycles

    10 days ago

    The top and bottom of that drum are relatively thin and not designed to support any force. I believe The holes you cut for rods will eventually deform or crack if you have any significant amount of compost in there. You need a system to distribute the force.

    1 reply
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    ShamuscgericCycles

    Reply 8 days ago

    Hi ericCycles. I haven't had any issues with the top and bottom of the drum warping around the holes yet and I've had the composter for a few months now. It would have at least 20kg of vegetable matter in it. I suppose it depends on which barrel you can get your hands on. The barrel I used was about 5mm thick plastic and feels pretty solid to me, but if you got a thinner barrel you might have an issue with that.

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    tlebsack

    10 days ago

    I'm composting in a back yard pile and my sister owns the store-bought version of what you have built. This is an excellent idea. What might help would be to make the platform tall enough to push a wheelbarrow beneath so that opening the door drops the new compost directly into the wheelbarrow. I also like the suggestion of putting the fins inside to aid stirring. I think that the clothes washing machine industry refers to these as baffles.

    1 reply
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    Shamuscgtlebsack

    Reply 8 days ago

    A platform for a wheelbarrow is a great idea Tiebsack! You might just need to strengthen the frame to handle the centre of gravity being higher up.

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    gman57

    Question 10 days ago

    Nice write up , but I would have liked to see the location and number of holes drilled into the barrel.

    1 answer
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    Shamuscggman57

    Answer 8 days ago

    HI Gman, apologies about that. I've now added two more photos in step 4 of the holes and their locations. Just for reference they were about 10cm apart, although this is just a guide, you might want to put more holes in it to get more oxygen.

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    GrahamW49

    9 days ago

    As an optional extra you could make a grid that fits over the door then leaving the door open and turning it would give you a pile of compost underneath but keep the uncomposted matter inside.

    1 reply
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    ShamuscgGrahamW49

    Reply 8 days ago

    Thats a really good idea! I actually put a small ball valve tap on the lowest point of the barrel to try and achieve the same effect as the grid, but it kept getting blocked up. The grid is a much better idea :)

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    ClintL2

    Tip 12 days ago

    You may want to put some screws into the length of the wall of the tumbler so that the compost doesn't just slide upon rotation of the drum. This is a quick and dirty way of snagging the organic material and forcing it to tumble. Conversely, you may want to install fins or paddles along the inside wall of the tumbler to perform the same function.

    1 reply
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    ShamuscgClintL2

    Reply 12 days ago

    Good suggestion! I've found that's an issue when I rotate the tumbler that it doesn't tumble the vegetation. I've taken to getting in there with a shovel to mix it all around instead, but I like you're idea better