<!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 6.00.2800.1276" name=GENERATOR></HEAD> <BODY bgColor=#ffffff> <DIV>Hi Ric,</DIV> <DIV> </DIV> <DIV><FONT face=Arial size=2>You're right!  You came up with = the same thing!  (duh)  8-P  Of course I did make it more user friendly.  ;-)  I think you have too much faith that people = know how to use mathematical formulae without being given detailed instructions.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>I <STRONG>also</STRONG> think...  = that you enjoy mathematics far more than you let on!  I always enjoyed = things mathematical -- very satisfying to solve a difficult problem.  My dissertation was very mathematical as well.  I do recognize others = who have caught this bug!  ;-)</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Peace,</FONT></DIV> <DIV><FONT face=Arial size=2>Sarah</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=Richard.Brekne@grieg.uib.no href="mailto:Richard.Brekne@grieg.uib.no">Richard Brekne</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">Pianotech</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, December 11, = 2003 1:50 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Rib = dimensions</DIV> <DIV><BR></DIV>  <P>Sarah Fox wrote: <BLOCKQUOTE TYPE="CITE"> <STYLE></STYLE> <FONT face=Arial><FONT size=-1>Hi = Terry,</FONT></FONT> <FONT face=Arial><FONT size=-1>OK, here's a more user-friendly method = for you that will give you the correct position of the rib anywhere along its length.  (You can also use this method to plot out points on a template.  Compute numerous points and connect the dots.  :-)</FONT></FONT> <FONT face=Arial><FONT size=-1>Clamp any = part of the rib against a flat surface, concave side up (soundboard side = down).  With this arrangement, let:</FONT></FONT> <FONT = face=Arial><FONT size=-1>h = the height of the rib above the flat surface</FONT></FONT> <FONT face=Arial><FONT size=-1>r = = radius of the rib</FONT></FONT> <FONT face=Arial><FONT size=-1>d = the = distance along the rib you are measuring, with respect to the clamp point.  = For instance, if you clamp in at the middle of a 4 ft rib and measure at = the end, d would be 2.  Of course this is approximate.  More accurately, d would be the distance from the clamp point to the = position <B>on the flat surface, directly underlying the measurement = point</B>.  (Think right triangles.)</FONT></FONT> <FONT face=Arial><FONT = size=-1>Then:</FONT></FONT> <FONT face=Arial><FONT = size=-1>h = r - Sqrt ( r^2 - d^2)</FONT></FONT> </BLOCKQUOTE> <P>Which is exactly what I wrote in my last post, exept I didnt = specify that you could measure anywhere along the rib... figuring that was kind of = self explanitory.. :) <P>""You could also do this simply by   r - Sqrt( r ^2 - (0.5L)^2)   L being the length of the rib. "" <BR>  <P>What I thought was neat about all the replies... is that we came = out with two basic approaches... solving for crownheight, and solving for = radius. So you can check either way you set up your rib jig. If you want a 60 = foot radius.. then use the above... if you want to use a certain = crownheight and want to be sure what radius you are imposing.. then use the formula = Ron N put out. <P>Cheers <BR>RicB <BR>  <P>-- <BR>Richard Brekne <BR>RPT, N.P.T.F. <BR>UiB, Bergen, Norway = <BR><A href="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> = <BR><A = href="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broad= park.no/~rbrekne/ricmain.html</A> <BR><A = href="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib= .no/grieg/personer/cv_RB.html</A> <BR>  </P></BLOCKQUOTE></BODY></HTML>