---------------------- multipart/alternative attachment In a message dated 11/13/2003 6:59:10 PM Pacific Standard Time, Crashvalve@aol.com writes: In a message dated 11/13/03 1:32:52 AM, Erwinspiano@aol.com writes: What do I mean? This will answer Crashvalves question as well. When pre-stressing a board with good legitimate crown values as I described, it does require having the plate in and secured with bolts & screws. Enough so that when driving the maple wedges between the struts and the bridge tops it (the plate) doesn't flex Dale Well drat, I was hoping you were talking about iterating some trigonometry that would use the string scale and degrees of downbearing and yield a down bearing in pounds. This then loaded onto the bridge to test board deflection. At this stage of soundboard build, the only variable left to tweak is plate set/downbearing, and knowing the amount of deflection expected from a board might be a good indicator of stiffness ? >>>>You get trig from Del & others. From me, well there are simple ways to figure angle of deflection. It's the rear length of the string from the front bridge pin to the aliquot times . 026 for 1 & 1/2 degree. .017 for 1 degree. This will give you distance bearing specs. I believe the average bearing force for a typical 160 lb. tension scale is a bout four pounds per string at 1& 1/2 degrees deflection. What I know is that pre stressing the board usually yields a similar deflection after it's strung. It's simple to measure from the strut down to the bridge top after the tension is on & I usually find about the same amount of squash that pre-stressing yielded. Sorry if this seems overly minute, but I seem to get farther along in just about any piano task if I can mike it up. BTW how did you measure that .400 panel ? I had the plate out & measured at the nose bolt holes. I have seen an un-mounted soundboard calipered using a dial indicator clamped to the top of a jigsaw (sans blade) but in the piano is different. I finished putting a .020 probe into the end of a depth mike Glenn ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/b7/d9/8a/92/attachment.htm ---------------------- multipart/alternative attachment--
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