<!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 5.00.2919.6307" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#d8d0c8> <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:davidlovepianos@earthlink.net" title=davidlovepianos@earthlink.net>David Love</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> Saturday, March 29, 2003 = 8:34 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> RE: Bridge = dimensions</DIV> <DIV><BR></DIV> <DIV><FONT face="MS Sans Serif" size=2>Perhaps it was a = misinterpretation of your previous post on the subject, but I though you said that part of = the reason for undercutting the bridge was to allow that part of the sound = board to be able to move freely up and down.  </FONT></DIV> <DIV><FONT face="MS Sans Serif" = size=2></FONT> </DIV></BLOCKQUOTE> <DIV><FONT size=2>Well, it's not going to be completely free, but it = does need some freedom of motion. </FONT></DIV> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV><FONT face="MS Sans Serif" size=2>That prompted my question = as it seemed that freedom to move up and down and stiffness, i.e. high impedance, = were at odds.  I think you've answered that question, but if the board is = going to move anyway, why bother to undercut the bridge other than to move = it away from the bellyrail?  Is it assumed that on a piano with a more = severely undercut bridge, it should have a more substantial rib configuration = to balance it and vice versa?  </FONT></DIV></BLOCKQUOTE> <DIV><FONT size=2>Ah. I think I see the question. Actually, through = the high treble the ribs are pretty much superfluous. The bridge body is so close = to the bellyrail--actually the soundboard liner--that the bulk of the required stiffness comes from the soundboard itself. More or less, depending on = the grain orientation (relative to the bellyrail) and the thickness of the = soundboard. It is not until the bridge gets some distance away from the bellyrail that = the ribs  begin to have any real effect.</FONT></DIV> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV><FONT face="MS Sans Serif" size=2>And given the choice = between more mass in the bridge or more substance in the rib configuration, what would = you choose?  Am I right in assuming that the more minimal = undercutting in a Steinway bridge is because the rib configuration is more = skimpy? ! If so, then would undercutting the bridge further on a Steinway create more = problems and a weaker treble if the rib pattern and height remained the same?</FONT></DIV></BLOCKQUOTE> <DIV><FONT size=2>Some Steinway bridges are minimally undercut. Others = have had the bejeebers whacked out of them. We've just replaced one on an L that = was cut back to no more than half of its already rather narrow width (mostly = less than 30 mm throughout) and was taken down to 24.5 mm high at C-88. = By mounting the plate so that the treble end was brought up to the same = height as the bass end (i.e., with the pinblock uniformly thick across its width) = the height of the new bridge is going to be about 30 to 32 mm. I expect = sustain will be a bit better</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>I haven't done a whole lot of work on the theory of = balancing the bridge dimensions off against the rib dimensions. I've evolved a = balance that works and try to stick with it. One of these days....</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Del</FONT></DIV> <DIV><FONT size=2>Delwin D Fandrich<BR>Piano Designer & = Builder<BR>Hoquiam, Washington 98550 USA<BR>360.532-2563<BR>360.532-6688<BR><A href="mailto:pianobuilders@olynet.com">pianobuilders@olynet.com</A></FO= NT></DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; = PADDING-LEFT: 5px; PADDING-RIGHT: 0px"><FONT size=2> <DIV> </DIV></FONT></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>