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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=Erwinspiano@AOL.COM
href="mailto:Erwinspiano@AOL.COM">Erwinspiano@AOL.COM</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> July 12, 2002 12:29 =
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Bridge =
design</DIV>
<DIV><BR></DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face="Times New =
Roman" size=2
FAMILY="SERIF"><I>In a message dated 7/12/2002 10:31:34 AM Pacific =
Daylight
Time, <A =
href="mailto:pianobuilders@olynet.com">pianobuilders@olynet.com</A>
writes:<BR></I></FONT></FONT></DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face="Times New =
Roman" size=2
FAMILY="SERIF"><I><BR></FONT><FONT lang=0 =
style="BACKGROUND-COLOR: #ffffff"
face=Arial color=#000000 size=2 =
FAMILY="SANSSERIF"></I> </DIV>
<DIV> Del</FONT><FONT lang=0
style="BACKGROUND-COLOR: #ffffff" face=Arial color=#000000 =
size=2
FAMILY="SANSSERIF"></DIV>
<DIV></FONT><FONT lang=0 style="BACKGROUND-COLOR: #ffffff"
face="Times New Roman" color=#000000 size=2
FAMILY="SERIF"> <FONT size=3> =
</FONT></FONT><FONT
lang=0 style="BACKGROUND-COLOR: #ffffff" face="Times New Roman" =
color=#000000
FAMILY="SERIF">Thanks <BR> Pre-molded rib =
radius. That
is slick. Makes sense. Any observations to tonal =
differences?
/superiority of Lam. ribs verses crown cut ribs? I suspect not and =
any
tonal enhancement difference is in the design. Still on the learning
curve.<BR> What about number of laminations? Have =
you
found an optimum? My thought is long deep ribs will require more =
thinner
lams. or less thicker lams. and shorter ribs the same thing depending =
on some
decision as to what's enough for adequate stiffness, consistency
etc.<BR> Economically more lams. means more
machining<BR> Dale =
Erwin</FONT></FONT></DIV></BLOCKQUOTE>
<DIV><FONT face=arial,helvetica><FONT face="Lucida Sans"
color=#000080></FONT></FONT> </DIV>
<DIV><FONT face=arial,helvetica><FONT face="Lucida Sans"
color=#000080> 1) Tonal =
superiority. All
things being equal I doubt there is any though I've done any specific =
testing to
prove this. I'm not sure how I could. There are too many other =
variations
job-to-job to be able to isolate just the one factor. In other words, if =
there
is a difference, it's not dramatic. The laminated ribs are more =
consistent
rib-to-rib since the variations of wood characteristics are evened out. =
For the
same reason I believe crown stability to be better and longer
lasting.</FONT></FONT></DIV>
<DIV><FONT color=#000080></FONT> </DIV>
<DIV><FONT color=#000080> 2) =
Number of
laminations. I know the lay-up schedule we use --it's different for each =
height
of rib -- whether that is optimum or not I don't know. It works and =
works
well.</FONT></DIV>
<DIV><FONT color=#000080></FONT> </DIV>
<DIV><FONT color=#000080> It's not really a matter =
of
'adequate stiffness.' The stiffness of the finished rib is going to be a =
function of the wood characteristic -- its stiffness, or its MOE -- and =
the
overall height and width cross-section. It's more a matter of how =
much
spring-back is allowable. When bent laminates are made there is always =
some
springback when the laminated is taken from the press. This is true =
whether a
glulam beam is being made for your church roof or a grand rim is being =
taken
from the rim press. A rib with more, thinner laminations has less spring =
back
than does one fewer, thicker laminations.</FONT></DIV>
<DIV><FONT color=#000080></FONT> </DIV>
<DIV><FONT color=#000080> 3) I did =
not start
developing and using laminated ribs as an economy move, though they =
probably
would be on a much larger scale of manufacturing. They certainly make =
better use
of excellent quality wood that would otherwise go to waste. Nor do we =
continue
using them for economy reasons now. Indeed, they are some more expensive =
for us
to make on our very small scale of manufacturing -- whacking out a few =
solid
spruce ribs would be some cheaper. We continue using laminated ribs for =
the
various reasons mentioned in earlier posts.</FONT></DIV>
<DIV><FONT color=#000080></FONT> </DIV>
<DIV><FONT color=#000080>Del</FONT></DIV></BODY></HTML>