<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML xmlns:o = "urn:schemas-microsoft-com:office:office"><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1226" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>----- Original Message = ----- </FONT> <DIV><FONT face="Comic Sans MS" color=#000080>From: "Richard Brekne" = <</FONT><A href="mailto:Richard.Brekne@grieg.uib.no"><FONT face="Comic Sans MS" = color=#000080>Richard.Brekne@grieg.uib.no</FONT></A><FONT face="Comic Sans MS" color=#000080>></FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>To: "Pianotech" = <</FONT><A href="mailto:pianotech@ptg.org"><FONT face="Comic Sans MS" color=#000080>pianotech@ptg.org</FONT></A><FONT face="Comic Sans MS" = color=#000080>></FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Sent: October 02, 2003 = 8:33 AM</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Subject: Re: RC vs CC again</FONT></DIV></DIV> <DIV><FONT face="Comic Sans MS"><BR><FONT = color=#000080></FONT></FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>> <BR>> All of = this suggests to me that in general, a CC board has an easier<BR>> time generating = a higher stiffness to mass ratio...as long as the<BR>> compression in the = panel holds. Yes ?<BR>> <BR>> RicB <HR> </FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>No.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Remember the stiffness = of the ribs increases directly with its width but with the cube of its = height:</FONT><FONT face="Comic Sans MS" color=#000080></FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><SPAN style="mso-text-raise: -12.0pt"> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><SPAN style="mso-text-raise: -15.0pt"><IMG height=54 src="cid:03c201c38908$8fe32e80$d2e2b1d8@Mainddf" width=102 v:shapes="_x0000_i1025"></SPAN><o:p></o:p></SPAN></B></P></SPAN><o:p></= o:p></SPAN> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><I><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><FONT color=#000000 size=2></FONT></SPAN></I> </P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><I><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><FONT color=#000000 size=2>y</FONT></SPAN></I><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><FONT color=#000000><FONT size=2> = deflection of beam (measured at = center)<BR>K = a constant (0.25 for a center-loaded = beam)<o:p></o:p></FONT></FONT></SPAN></P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><FONT color=#000000><FONT size=2>P = load on beam (at center)<o:p></o:p></FONT></FONT></SPAN></P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Lucida Sans'; = mso-bidi-font-size: 10.0pt"><FONT color=#000000><FONT size=2>E = modulus of elasticity (1.57 x = 10<SUP>6</SUP> for Sitka spruce)<o:p></o:p></FONT></FONT></SPAN></P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><FONT = color=#000000><FONT size=2><SPAN><EM>l</EM> = length of = beam<o:p></o:p></SPAN></FONT></FONT></P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><FONT = color=#000000><FONT size=2><SPAN><EM>b</EM> = width of = beam<o:p></o:p></SPAN></FONT></FONT></P> <P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><FONT = color=#000000><FONT size=2><SPAN><EM>d</EM> = depth of beam<o:p></o:p></SPAN></FONT></FONT></P></FONT><FONT face="Comic Sans = MS" color=#000080></FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>... and we get to = manipulate both the height and the width of the rib. I can make that rib enormously = stiff before I run into mass problems.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" = color=#000080>Del</FONT></DIV></BODY></HTML>