The Drying Trays
The trays used in the prototype were a bottomless box with copra-netting nailed into the bottom and steel wheels bolted onto the sides. These proved awkward to build and clumsy in practice.
The frame-based tray shown would allow different flooring options and replaceable runner strips.
Rail track
Vassa runner strips on vassa rails is the recommended track system because it is simple, local and cheap. If available, heavy-duty castor-wheels could be mounted under the tray frame. For this size of tray two wheels, centrally mounted, would be enough.
Tray Flooring
Decking options include: netting, sheet-steel, corrugated-iron, timber, plywood.
An internal tray width of 0.9m. matches the size of copra/cocoa mesh. This gives the trays an overall width of 1.0m.
This dimension matches those given elsewhere in this manual. It is also suitable for flat galvanised sheet, which can be angle-bent over the side-rails.
Tray Frames
The frame for the trays is built up from (75 x 50mm) timber.
The accuracy and straightness of the frame pieces is very important since the runner strips fitted to the bottom edges must be straight and parallel. When fitting the floor it is also advisable to nail or clamp the frame to a flat surface to prevent it distorting at this last stage. Note that the front end is made oversized, like a drawer front, to block the opening when the tray shuts. This can be added last.
This frame has been covered in sheet metal.
Sheet-steel (26G) is the preferred option, because …
(a) it is about ½ the cost of netting, and
(b) it will conduct heat to underneath the beans, assisting with drying.
Materials list
Piece |
Size([mm] |
Lgth [m.] |
Qty. (ea) |
x 8 |
Rails |
75 x 50 |
2.1 |
2 |
16 |
Cross braces |
75 x 50 |
1.0 |
4 |
32 |
Front board |
200 x 25 |
1.0 |
1 |
8 |
End board |
150 x 25 |
1.0 |
1 |
8 |
Runners (vassa) |
75 x 25 |
2.1 |
2 |
16 |
[Side boards] |
150 x 25 |
2.1 |
2 |
16 |