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<DIV><EM>Dale Erwin wrote: Is that a Weber grand? </EM></DIV>
<DIV><EM></EM> </DIV>
<DIV><FONT size=3>1890s Knabe.</FONT></DIV>
<DIV><EM></EM> </DIV>
<DIV><EM>What does the bathroom scale say the psi per go bar is 100 lbs =
or
so?</EM></DIV>
<DIV><EM></EM> </DIV>
<DIV><FONT size=3>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.</FONT></DIV>
<DIV><EM></EM> </DIV>
<DIV><EM>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 </EM></DIV>
<DIV><EM></EM> </DIV>
<DIV><FONT size=3>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.</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>The first time I did that was a MAJOR "Ahh-Ha" =
moment for
me!</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>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.....).</FONT></DIV>
<DIV><EM></EM> </DIV>
<DIV><EM>I'll bet I know what it is.</EM></DIV>
<DIV><EM></EM> </DIV>
<DIV><FONT size=3>What?</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>Terry Farrell</FONT></DIV></BODY></HTML>