> There was a discussion some time back about calculating the load per rib but > I can't find it. Do you simply average the number of unisons per rib in > that section and calculate the load accordingly? > > David Love I use the diabolically clever and highly sophisticated method of looking at where a line half way between and parallel to the ribs intersects the bridge and noting the unison numbers at those points. Using these physical observations, each rib is assigned the total bearing load of the unisons it will be carrying in the piano at the presumed bearing angle and calculated tensions from the scaling spreadsheet. Unison loads down scale of the line go to the rib immediately below the line, and unison loads up scale of the line go to the next rib up. In other words, I look at the layout and see which ribs are carrying which unisons and add up the unison loads for each rib. The deflection of each rib is then computed with the accumulated load for each, and that gives me some idea of the load capacities of every rib in the system. I then diddle rib dimensions, number, and/or bearing angles until I like the interrelated results of calculated deflection under load of the system, and build it. Every rib is doing a specific job, and I'd like some idea of what that job is for every single rib. It's really not remotely mysterious or tricky. It just takes plain old time, thought, and work. Making sense of the outcome in terms of tone production is about the only thing that will take some accumulated experience and educated judgment - within the scope of what type of rib support system you're using (RC, or RC&S). The rules are different for each. I have no clue whatsoever how to design a CC board, so that one's not on the list. Ron N
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