Improved Flap Valves
by John Smith
|As the flap valves are inaccessible once the bellows have been covered,
I have given the following tip to ensure correct operation of the valves:
I suggest replacing the shorter, rounded strip of soft leather with a strip of the same material (or the blackout material) about 6 to 7 inches long, and 1 1/4 to 1 1/2 inches wide. This is to be laid over the inlet holes and fixed at both ends with a small strip of wood and glue - as in the plans. The material should be not stretched, but not too loose, either - just laid flat on the board and fixed. It only has to lift about 1 mm or so to allow air to pass in sufficient quantity.
I suggest that this method could be used for all the valves, and would produce a more consistent and 'quicker' action, resulting in better air pumping.
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