DISCLAIMER: THIS IS NOT A NEW IDEA. IN FACT, IT’S A BUILD OF A COMPOST SIFTER I SAW HERE:
Simply put, it’s three second-hand bicycle rims screwed to some batons and mounted onto a frame that sits on top of a wheelbarrow. You load up the cylinder with compost and as you spin the cylinder smaller bits of compost ready to go on the garden fall through the wire mesh. Larger bits are deposited out the end for further composting. Costa’s video is straightforward and easy to follow. In need of more detail, I have undertaken the build and recorded it here in my own worm compost sifter.
WARNING: I have a year 8 pass in woodworking, so some of the steps can probably be done better! Also, be careful with the tools kids and use the appropriate safety gear.
The compost sifter is ideally used as a faster way to sort worms from worm compost. The 6mm wire I eventually used, should be small enough to stop worms dropping through into the finished vermicompost.
However, some smaller worms and also cocoons in the worm compost will fall through the wire. You can either sort through the sifted worm compost to retrieve the worms or leave them where they are. A more thorough sorting method is to take the finished worm compost and place it under a light source.
Worms are photovores and will naturally burrow towards the centre of the pile. After giving the worms ten to twenty minutes to burrow begin scraping the worm compost away. It should be devoid of worms or only have a few slow coaches left behind.
Step 1: Tools Needed
- Wood for the frame – This is store bought. Dimensions are 1200mm by 70mm by 30mm. Costa’s video, rightly suggests, that you can also use any recycled wood to build the frame. A recycled pallet would be ideal.
- Wood for batons. This is used to screw the bike rims and form the cylinder. Each baton is 1200mm by 42mm by 19mm.
- Bicycle wheel rims. I was able to pick these up at a local bike recycler for $AU10 each. Most bicycle shops or bicycle repair places should have some lying around. The gentleman at Bicycle Recycle was very confused when I needed three rims and probably MORE confused when I explained I was going to use them to make a worm compost sifter.
- An angle grinder. While not mandatory, it makes removing spokes from the bicycle rims much easier.
- 4 castors. These were chosen to be small enough to fit inside the bicycle rims to turn the sifter.
- A square and pencil to make sure that all the lines are straight and true.
- Pliers are a much more labour intensive way to remove the spokes from the bicycle rims.
- Electric drill because screwdrivers are so last century.
- A hand saw and sawhorse for cutting the pieces of the frame and the batons to the right length.
- Screws to assemble the frame and attach batons to the bicycle rims.
- Tape measure.
- Tin snips.
- The wheelbarrow is pretty important. It is these measurements that will determine the size of the frame.
- The wire mesh lines the inside of the bicycle rims and forms the sifter. The original wire mesh I used was too big and I changed it for 6mm square wire used in aviaries to help keep out pests like mice.
Step 2: Worm Compost Sifter Build Instructions
CONSTRUCTING THE FRAME:
The frame is constructed to fit over the top of the wheelbarrow.
The frame is four pieces of the larger wood lengths. Two lengths match the width of the wheelbarrow and two matches the length of the wheelbarrow.
NB: Make sure the body of the wheelbarrow is square. The one pictured is slightly wider at the top than at the bottom. Make adjustments to the layout of the frame appropriately.
CONSTRUCTING THE CYLINDER:
The cylinder is three bicycle rims with the spokes removed and they are then fastened to the batons. You CAN remove the spokes with a pair of wire cutters, pliers or a screwdriver but do it with an angle grinder; it is so much more fun. Spokes are under tension and the first few will “ping” as the tension is broken. With an angle grinder.
Attaching the bicycle rims to the batons
Two of the three bicycle rims are attached with screws. The third is purposely not attached so that it can be adjusted once the castors are attached.
The castors are held in place with four screws. Because the spacing of the castors and the bicycle rims may need adjusting, hold the castors in with only one or two screws before final positioning of the cylinder is finished.
This bit is a bit fiddly. The third rim should only be attached once the correct adjustments for fitting the castors into the first and third rim.
Cut the wire used to sift the compost to length. It should be slightly larger than the circumference of the bicycle rims. Then it can be rolled up and fed down the centre of the cylinder. Unwind the wire inside the cylinder and attach it to the batons using the plastic ties. The fun of this is that these are the one-way plastic ties. There’s no coming back from this.
NOTE: There are two rolls of wire attached to the cylinder. The wire turned out to be about 30mm short, which required cutting and attaching the second roll of wire. Once the correct sized wire is attached, you should have something that looks like this:
Which produces this BEAUTIFUL black gold. Or worm compost if you’re slightly less excitable.
I hope this has been helpful. If you have any questions, please email me or reach via The Gentleman Vermiculturist