---------------------- multipart/alternative attachment Ron By the way you sent this thru last week & I didn't have time to say it was very well described & if one takes time to really anaylisze the dynamics of this rib design the vibrational effiecncy of this shape rib seems ... transparent. The way you described it made it crystal clear in my thought process & I hope others. I catch on quick after a long time! What about using the same approach with a solid rib. The only difference in our procedure as to shape has been not using as much of a straight taper at the rib end. Vibrational waves emanating at the bridge & radiating outward is all s.o.p. thought and this rib design whether it be laminated or not seems to aid the idea of the soundboards center as the starting point for vibration & also showing the most movement. Dale > Are we say the same thing in a different language? i.e.. A one inch > square rib until the taper begins?. Then it becomes ...tapered? > Dale Almost. Crowned top, flat bottom, taper feathering. I cut 'em to depth on a table saw, so the thickest part is in the middle. I make no attempt to keep the section depth constant through the center, and would prefer not to even if I could easily do it. They're a taper of one sort or another from the center point to just inside where they meet the rim. I want them to bend as uniformly as possible, like a bow, so stress is evenly distributed and vibration response is from the whole rib (and membrane) at once. At least, that's the intent. Make a 1/3-1/3-1/3 taper-straight-taper test rib, and another of the same dimensions with conventional tapering. Support the ends and load the center. The taper feathered rib forms a nice smooth continuous arc, or if it was constant radius crowned to begin with, it deflects to a nearly straight line under the right load. The conventionally feathered rib shows a tight bend in the feathered sections, a relatively straight run, and a relatively tight bend in the center where the load is. The tight bends are the high stress areas. while the relatively straight sections aren't responding like they could. The conventional rib shape just wasn't very well designed as a load bearing member, which is why I use the shape I do. It does what I think I want it to do. If I had an easy way to do it, I'd probably crown the bottom of the rib too, but the taper is easy and quick with a router jig, even though it buries me in chips, and works pretty well. Ron N _______________________________________________ ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/c8/95/e8/32/attachment.htm ---------------------- multipart/alternative attachment--
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