709-218-7927 The Landfall Garden House 60 Canon Bayley Road Bonavista, Newfoundland CANADA A0C 1B0 |
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Hand Driven Trommel
All trommels are cylinders of mesh; the most popular domestic model uses bicycle rims as the circular framework.
This YouTube video screenshot shows a small drum, two bicycle wheel rims, four pieces of wood for stiffening of the frame. To the left an operator rolls the drum by hand, to the right an operator introduces raw material to be sieved.
The drum rides on castors (circled) which fit beautifully into the rims, The castors are on a wooden frame, notched to remain in place atop a wheel barrow.
I am the only operator and do not want to switch sides or tools for each load. As well I suspect that manual operation suits a few wheelbarrow loads, but will not be a good way to deliver a thousand cubic feet of sieved soil.
Note that a mesh of any grade (coarser, equal or finer) can be rolled into a liner cylinder longer than the bicycle-rim cylinder to provide an extended length, and hence period of sieving.
This screenshot from a YouTube video shows a small extension – about three inches – at the output of delivery end of a trommel. The extension could be longer because by the delivery end (in theory) all we have is robust rolling coarse material, of very little mass. I am assuming that you do NOT toss six-inch diameter rocks into a trommel of this size.
At the reception or “top” end a similar extension, perhaps up to one foot, could be used to catch those introductory and farewell dribbles of soil from the shovel as it approaches and recedes from the delivery stroke. Again, these dribbles will be of low mass and so can be supported by a flexible section of mesh.
If you have made your extensions too long, trim them by one inch each day that they seem to be too long.
At the 3m30s point in the video the builder mentions replacing the mesh-weaving plastic ties with a bar; I suppose that the bar will add to the rigidity of the mesh cylinder; sounds good!
4m10s put the castors on a sliding (adjustable) plate to improve alignment.
5m50s “move the trommel along as we …” I start thinking that as I roam the bed, I could add rotted compost at each movement, producing a heap of sieved soil mixed with partially-composted fibres, all of small grade.
7m39s We studied this method in High School Chemistry classes with Mr. Crosby. “ Zone refining ”
8m0s Notice the excess movement; the operator’s body must move about five feet with each shovelful. Obviate this by attaching a small galvanized funnel so that shovels can by dumped from any direction.
8m18s “took about six hours” but note that the operator is digging out sod, not just re-sieving an existing bed.