<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1106" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT color=#800080>Hello Gene Nelson. You will find a better = chance of someone responding to your post if you use an appropriate subject line = (many will just delete no subject). And it is nice to sign your = posts.</FONT></DIV> <DIV><FONT color=#800080></FONT> </DIV> <DIV><FONT color=#800080>I will intersperse a few thoughts I have on = your questions. I don't think I really have any answers for you, as so much = of this is still a bit nebulous to me also. But maybe together we can bug = someone knowledgeable into responding!</FONT></DIV> <DIV><FONT color=#800080></FONT> </DIV> <DIV><FONT color=#800080>Terry Farrell</FONT></DIV> <DIV> <SPAN id=__#Ath#SignaturePos__></SPAN> </DIV> <DIV>----- Original Message ----- <DIV>From: "Nelson. Gene (PWA)" <<A href="mailto:nelsong@SacCounty.NET">nelsong@SacCounty.NET</A>></DIV>= <DIV>To: <<A = href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV> <DIV>Sent: Sunday, January 19, 2003 1:43 AM</DIV> <DIV>Subject: (no subject)</DIV></DIV> <DIV><BR></DIV> <DIV>> Please help a newbee understand. <BR>> <BR>> I am trying = to picture where the stiffness is in soundboards. If you<BR>> consider = the typical compression type that has ribs and board pressed into a<BR>> = caul, then the ribs are pulling the board toward the flat side or the<BR>> = position that the ribs want to come to rest. Is this creating stiffness = in<BR>> the soundboard?</DIV> <DIV> </DIV> <DIV><FONT color=#800080>The ribs are trying to flatten out, but = the panel will only compress so much, so you end up with some crown. So I think = your question is: is compression-generated crown responsible for = soundboard stiffness. Good question. Or is the stiffness simply a characteristic of = the material properties and dimensions. (My gut tells me the crown will = add to the stiffness, but I know what I am picturing is the dome-and-buttress = thing which does not appropriately apply.)</FONT><BR> <BR>> The reason I = ask is that recently I had a chance to be instructed on how to<BR>> handle a = new soundboard out of the box without ribs attached. It quickly<BR>> = bacame obvious how fragile they are in this state. Any mishandling = could<BR>> easily cause a fracture. Then I think about the grain orientation and = how<BR>> the bridges are aligned to this with exception of the extreme treble = and<BR>> maybe some of the bass. Along the grain is the weakest part of the board = -<BR>> am I wrong? So where is the stiffness. </DIV> <DIV> </DIV> <DIV><FONT color=#800080>I have noted the same thing. The unribbed = panel can be like a wet noodle. But only ACROSS the grain (perpendicular to the grain = or long axis of the tree). The panel has a fair bit of stiffness along the = grain. The long bridge will add to the along-grain stiffness. After ribs are glued = to panel more-or-less across the grain, the soundboard will have stiffness both = along and across the grain.</FONT></DIV> <DIV> <BR>> Also curious, is board stiffness something that can = be calculated?</DIV> <DIV> </DIV> <DIV><FONT color=#800080>No doubt! Del?</FONT></DIV> <DIV> </DIV> <DIV>> Is it a factor in rib design?</DIV> <DIV> </DIV> <DIV><FONT color=#800080>I'm sure overall stiffness is going = to be the combination of the physical properties of the panel, = bridge and rib (and maybe the shape, as in crown?).</FONT></DIV> <DIV> </DIV> <DIV>> Is it used to calculate how bearing is supported? </DIV> <DIV> </DIV> <DIV><FONT color=#800080>I suspect the answer is that is should be. = I'll bet there are many factory sad/horror stories related to this not being = taken into account?</FONT></DIV> <DIV> </DIV> <DIV>> Or is board stiffness related only to musical qualities? = </DIV> <DIV> </DIV> <DIV><FONT color=#800080>Another I don't know the answer to. I suspect = it will also relate to soundboard longevity.</FONT><BR> <BR>> Thank you = very much.<BR></DIV> <DIV><FONT color=#800080>And thank you for posting some interesting = questions. Let's hope some knowledgeable soul can shed some light here.</FONT></DIV></BODY></HTML>