Sorry I'm slow in responding to this but have been away a few days. I can't speak for Ron's designs but we have compared notes on occasion. My approaches on these vary so it may be a hard side by side comparison. I don't always do a full bells and whistles treatment. My most basic approach is with original rib positions, unmodified plates (except installation of new counterbearing bars and aliquots where needed), bass cut-off and often modified bass bridges to increase backscale length and shorten or eliminate cantilevers. I always install a bass cut-off bar (can't see any reason not to have one). I don't always do radial rib patterns, vertical hitches, transition bridges, treble fish, bass floats. It depends on the scope of the job, what the customer wants etc.. I have gone to modestly increased grain angles (from 45 to 50 or 55 degrees) I don't usually go to 60 degrees as some do. I still thin the panel if the bass is not floated but only on the bent side and mostly behind bass bridge and on the treble shelf--down to about 4-5 mm and starting about 100 - 125 mm from the edge. I don't do full diaphragmizing. The straight side and the belly rail side are full thickness, usually 8-9 mm depending on the piano. Rib radii are chosen depending on the length of the rib, the target amount of crown and the targeted residual crown after loading. Thus, shorter ribs tend to have a tighter radius. With a full cutoff bar and treble fish installed the overall rib lengths will tend to be much shorter which will tighten the radius overall. The middle 1/3+ (varies a bit) is at full height and a longer gradual taper starts at that point (no big scoops out at the end of the ribs). About 10 or 11 mm of unloaded crown on the longest rib is all I want--considerably less on the shorter ribs. Rib dimensions are based on beam deflection formulas and the calculations of the stiffness of the entire assembly are derived from the ribs and without factoring any compression from the panel. I want around 40% residual crown after loading depending on where in the scale. I rib the boards between 6 and 6.5% EMC mostly. While I calculate the rib dimensions for a loading of around 550 lbs for a small to medium grand and maybe up to 650 for a larger grand (D excepted), I don't actually load the boards that much when actually strung. My bearing settings have backed off considerably from when I began this. The whole range (ideally) is probably between .5 (bass without any significant cantilever) and 1.25 degrees in the treble which I probably get by note 64 and continue to the top. The very top of the treble, I find, doesn't need any more bearing than that. The actual rib deflection formulas that I'm using are still evolving somewhat and I'm not ready to part with them quite yet. As Ron mentioned, the entire process continues to evolve (slowly), and since I employ different approaches on different pianos it complicates things a bit. David Love www.davidlovepianos.com If there were a way that would not jeopardize proprietary info, I think it would be highly useful to collect and sort through the varied experience of people working their own approaches to the RC&S concept to confirm common trends and combine the communal intelligence. For instance, I think I have a reasonable idea how Ron defines stiffness throughout the scale, but I'm completely guessing on Davids definition of stiffness. I get the feeling David's radii are larger than Ron's, and calculated rib loading is less than Rons. Without specifics though the communication is somewhat limited. It there were some way to share specifics(and I'm not sure how to do this without giving away proprietary stuff) I think the combined empirical intelligence which could come out of these discussions could be substantial. I'm not sure what I'm asking for here...I wonder if it would be useful and instructive to design a panel discussion specific to RC&S for the convention? Since it would clearly be defined as specific to RC&S concepts, and moderated to keep on that topic, we could avoid the head butting regarding CC vs RC&S ad nauseum and focus on combining the knowledge & experience of RC&S concepts which have been collecting independently in our shops. Jim I -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA
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