This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Dale Erwin wrote: Is that a Weber grand? =20 1890s Knabe. What does the bathroom scale say the psi per go bar is 100 lbs or so? Well, you can make the cross-section dimensions and lengths so that they = exert whatever pressure you want. I simply find it easiest to use two or = three go-bars for each string section. Most of them are in the 50 - 60 = lb. range - but like I say, just dimension the go-bar so that you get = whatever pressure/weight you need. I'd be interested as to how much precompression your board is showing in = this condition. You can measure it in mm at the three treble plate = struts before & after stressing =20 Or, for a much more complete picture, you can measure the change in = crown at all accessible ribs! That's what I do. You get dirtier and say = more nasty words, but you sure get a great picture of what is happening = down yonder. I tape a string at one end of the panel near a rib and hold = it to the panel at the other end of the rib. Then I use a series of = little feeler-gauge wooden blocks that I made up (in half-millimeter = increments) to see which one will just fit between the string and the = panel bottom. I do that at all accessible ribs both before pre-stressing = and with the board loaded. The first time I did that was a MAJOR "Ahh-Ha" moment for me! On one belly on a very small grand we did we found that we were not = seeing the compression we were expecting after loading. So we ended up = planing some of the ribs down a tad and then everything was fine. Had I = not evaluated loaded crown deflection in this manner, I might have = produced a piano with a too-stiff soundboard (I suppose crown would have = lasted for a couple hundred years.....). I'll bet I know what it is. What? Terry Farrell ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/5d/10/2a/25/attachment.htm ---------------------- multipart/alternative attachment--
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