709-218-7927 The Landfall Garden House 60 Canon Bayley Road Bonavista, Newfoundland CANADA A0C 1B0 |
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Crammed Rack
The crammed rack is the regular rack driven by a cam wheel. The cam wheel is an off-centre wheel which raises and lowers the lower end of the rack.
I found that my 2022/23 dropped rack was reluctant to deliver the coarse grades from the lower end of the rack, because the lower end coincided with the pivot or axle. Had I used a shorter mat (or a longer frame), there would still have been enough motion at the end of the mat to cause the coarse material to travel off the end of the rack.
It seems to me that a cam mounted at the lower end will provide minimal vibration at the upper end to start the material moving, and that the coarse material will move faster as it is freed of the finer material.
Here is the value of modular components; I should be able to try a lower-mounted cam and an upper-mounted cam.
The rack will be suspended by cords and/or tension springs, or sitting on compression springs (such as valve springs from a car engine).
I plan a proof-of-concept using my electric drill with an axle on which is mounted a cylinder of wood, about two inches diameter and perhaps three inches long.
The position and diameter of the cam must be matched to the rotational speed of the drill. I need enough power (energy per unit time of rotation) to lift the end of the rack and allow it to drop by gravity to provide the impact.