There is another type of bin developed recently where the bin is top fed but inverted (flipped over) for easy harvesting via a removable bottom. They have a locking lid and are inverted by rolling over, pivoting on a stand or simply turned upside down manually. Like the 'flow through' bin this type also provides excellent aeration from the top and bottom.

Here are a couple of examples from YouTube:

Easy Roll Worm Composter

Flip-Flop Worm Bin

After having a storage tote for nine years and experimenting with a flow through bin I found preferred different aspects of each. The 'top feeding' method used with a flow through was tidier (no digging required) than the 'pocket feeding' used with the storage tote. Also I prefer to harvest the vermicompost in large batches rather than continually from the flow through.

An inverting bin which can be both top fed and batch harvested seemed ideal for me. I decided to modify my small DIY flow through worm bin by replacing the fixed bottom grate with an easily removable bottom. This bin weighed about 13kg (29lbs) when full which will be manageable for me to manually invert the bin for harvesting. Any larger bin would likely require a mounted pivoting or rolling design similar to those shown in the video links above.

This is a small readily portable bin suitable for limited amounts of organic waste. It had been fed an average of about 460 grams (1 lb) per week during the 28 months it was used as a flow through and was harvested five times. I believe harvesting just twice a year will be possible while maintaining the same level of waste input.

My flow through bin is made of two 20 litre plastic pails nested together. For the modification first the wires of the grate were cut and removed. A removable bottom was made from an old Melmac dinner plate with a grid of holes drilled in it for drainage and aeration. In normal daily use the plate rests on two heavy gauge wire supports inside the base at the level of the bottom of the inner pail. For harvesting or maintenance the inner pail is lifted out of the base and inverted. While being lifted the plate is held to the bottom of the inner pail by plastic twine laced through the holes for the old grate wires. The twine/lacing can be easily removed from the inverted pail to allow the plate to be removed for harvesting. Both being plastic, neither the twine or plate will corrode.

Another old dinner plate will be used as a lid for the pail to use when inverting it. Coat hanger wires inserted through holes in the rim will hold the lid and contents in place when the pail is inverted.

The nesting pail design used in the original flow through version was needed to collect the castings as they fell through the bottom grate. This inverting bin could be easily made from just a single pail. Holes would be drilled in the bottom and the lower 2cm (1") of the pail wall for aeration and the lacing. Then the pail bottom would be cut out and suspended 2cm (1") up in the pail with heavier lacing. A pail lid and drip tray would complete the bin.

Here is a link that might be useful: Inverting Worm Bin by Boreal Wormer

This post was edited by boreal_wormer on Mon, Jun 17, 13 at 15:33