<!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 6.00.2900.3243" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face=Arial><BR><FONT size=2></FONT></FONT> </DIV> <DIV><FONT face=Arial size=2>> Percent residual crown doesn't tell you much in a system that has variable<BR>> radius control.  If you start with a rib that has 10 mm of crown and deflect<BR>> it 5 mm it has 50% left.  If you start with a rib with 5 mm of crown and<BR>> deflect it 5 mm it has 0%.  But they both have the same amount of deflection<BR>> for the given load. </FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2><STRONG>Thank you David!</STRONG></FONT></DIV> <DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV> <DIV><FONT face=Arial size=2><STRONG> I keep trying to make this point: <FONT color=#ff0000 size=3>we should all be including the span with our crown data, without which the data is absolutely meaningless! </FONT></STRONG></FONT></DIV> <DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV> <DIV><FONT face=Arial size=2><STRONG>Further, if we can't predict this sag, we can't predict the dynamic bearing and angle of string deflection, which means we don't know the pressure and are going to have a rough time of making any rib scale that isn't a shot in the breeze.</STRONG></FONT></DIV> <DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV> <DIV><FONT face=Arial size=2><STRONG>BTW, while I don't make CC boards anymore,  I did apprentice in a shop for several years that made about 20 CC boards a year and I have to say it was like being in the Wild West. We were total cowboys. The only thing we paid attention to was emc (3.5%). Rib dimensions came right off the old board, the compression crowning was all over the place depending on the time of year and size of the panels/ribs, and we set distance bearing with the spare change in our pocket. Yee haw! Boy were those days fun and also one of the reasons that I'm so compulsive now. :)</STRONG></FONT></DIV> <DIV><STRONG><FONT face=Arial size=2></FONT></STRONG> </DIV> <DIV><FONT face=Arial size=2><STRONG>Jude Reveley, RPT<BR>Absolute Piano Restoration, LLC<BR>Lowell, Massachusetts<BR>(978) 323-4545</STRONG></FONT></DIV></BODY></HTML>