A wooden I-beam is clamped to the case and the spring-loaded go-bars press the board to the ribs. The ribs are supported from underneath. Tension is regulated by the length of the dowel of length of threaded rod. Made from hardware store items, PVC pipe and end caps, spring, dowels, 3/8" threaded rod. I like the threaded rod best because of its dynamic adjustability. In the foreground on 917, notice the wedge under the block of wood. The block is pivoted against the strut to press the board on the other side. Jon Photos at: http://tinyurl.com/3h97v http://tinyurl.com/2lpul http://tinyurl.com/33cc5 Direct ptg.org URLs: https://www.moypiano.com/ptg/files/attachments/3c/60/27/65/Sprngprss.jpg https://www.moypiano.com/ptg/files/attachments/d9/cf/47/36/925.jpg https://www.moypiano.com/ptg/files/attachments/ac/46/e8/90/917.jpg
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