I've been thinking a bit about how the calculated rib scale allows you to design a spring with known stiffness, and have setup my spreadsheets and belly experiments to predict and adjust this quantifiable stiffness/flexibility (spring). As has been mentioned, there are other parameters such as back scale and grain angle, panel tapering or not tapering which also effect "stiffness". I put "stiffness" in quotes because ribs design targets and creates a spring while these other parameters, backscale etc either restrict or avoid restricting that spring...they don,t create spring. They are often referred to as having "stiffening" qualities but I'm thinking that there is a structural and tonal distinction between stiffening as the result of spring rate of a rib and "stiffening" as the result of limiting movement of the rib spring. David Love, it sounds like you've played around with various grain angles on calculated rib boards. Have you experimented with the traditional 45ish degrees, ie somewhat parallel to the long bridge, board angle? Most of the rc&s boards I seen or hear about assume that the slightly greater 50-55 to more is an improvement, while some push 70deg. It seems as if the tenor and bass would appreciate the near full crossgrain effect of grain parallel to the tenor in the long bridge. As in most belly issues, I suspect that the tradeoff was made to help out the treble, ie keep the rib weight down in killer octave by "stiffening" the board in that area. Are there any calculated string load/rib scale folks working with low grain angles? Jim I -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA
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