<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=iso-8859-1" = http-equiv=Content-Type> <META content="MSHTML 5.00.2314.1000" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A href="mailto:dbhersh@home.com" title=dbhersh@home.com>Doug = Hershberger</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = href="mailto:pianotech@ptg.org" title=pianotech@ptg.org>pianotech@ptg.org</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> January 07, 2000 2:22 = PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> setting up for = installing soundboards</DIV> <DIV><BR></DIV> <DIV><FONT size=2>Dear List,</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>My questions to those of you with experience are = as follows;</FONT></DIV> <DIV><FONT size=2>1. what are your thoughts pro/con on = atmospherically crowned boards</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>It is the so-called "traditional" method of = crowning soundboards.  However, by even the very early 1900s, = designers and builders were discovering its limitations.  See Wolfenden's book.</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>The basic limitations are:</FONT></DIV> <DIV><FONT size=2>    1)    The = results are highly dependent on variabilities in atmosphere and wood.</FONT></DIV> <DIV><FONT size=2>    2)    It places = extremely high stress loads on the wood fiber leading to rapid breakdown of same.</FONT></DIV> <DIV><FONT size=2>    3)    = Performance is unpredictable.</FONT></DIV> <DIV><FONT size=2>    4)    Life span = is unpredictable.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <DIV> </DIV> <DIV><FONT size=2>2. Is the other method, radiusing the ribs and = pressing the ribs/board into a caul of some sort?</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Yes, this is the other method.  Or some = combination of the two.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <DIV> </DIV> <DIV><FONT size=2>3. (this one is my question) What do they mean = when they say 60 ft radius as it applies to soundboard crown?</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Just that.  In theory, at least, the radius = of the curve of the soundboard along the rib is 60 feet (approx. 18 m).  = Someone, somewhere, has decided that this amount of crown was the = "correct" amount.  It rarely -- if ever -- works out in practice and even = if it did, the theory is incorrect.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <DIV> </DIV> <DIV><FONT size=2>He seemed to think that Steinway uses the = atmosphere type method. I told him when I was there I didn't remember which method = they used but they had a very expensive machine for precisely cutting around the = perimeter of the board so that it would tightly fit the inside of the = rim. Maybe that tight fit, plus gluing onto a angled shelf, plus = diaphragmatic taper all contribute to their boards holding their crown. = </FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>That is the method used by Steinway (unless they = have changed their process in the past several years).</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Yes, Steinway does have a wonderful machine for = trimming the soundboard to fit the rim.  This has nothing to do with forming = crown or with sustaining it, however.  Nor does the angled shelf (inner rim).</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Thinning the soundboard panel through the treble = section actually reduces the compression-crowned soundboard's ability to = maintain crown over the long term.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>I might mention that these are some pretty basic questions.  Usually when a technician moves into soundboard = replacement they have already been answered.  It might be wise for your = friend to do some serious studying before tackling a project like this.  It is = very costly to equip one's shop for soundboard work -- whether you purchase = the necessary tools or purchase them, it is still going to be = expensive.  Then there is the performance of the finished product to = consider....  </FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Regards,</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Del</FONT></DIV></BLOCKQUOTE></BODY></HTML>