<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=windows-1252"> <META content="MSHTML 6.00.2600.0" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT color=#008000>Comments interspersed below:</FONT></DIV> <DIV> <SPAN id=__#Ath#SignaturePos__></SPAN> </DIV> <DIV>----- Original Message ----- <DIV>From: "Delwin D Fandrich" <<A href="mailto:pianobuilders@olynet.com">pianobuilders@olynet.com</A>>= </DIV> <DIV>To: <<A = href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV> <DIV>Sent: Thursday, July 18, 2002 11:15 AM</DIV> <DIV>Subject: Re: Untapered Soundboard Ribs</DIV></DIV> <DIV><BR></DIV> <DIV>> <BR>> ----- Original Message -----<BR>> From: "Farrell" = <<A href="mailto:mfarrel2@tampabay.rr.com">mfarrel2@tampabay.rr.com</A>>= <BR>> To: <<A = href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>><BR>> Sent: July 18, 2002 3:48 AM<BR>> Subject: Untapered Soundboard = Ribs<BR>> <BR>> <BR>> > The Mehlin grand I worked on the other day had = untapered ribs on its<BR>> soundboard. Ribs on other pianos are somewhat = abruptly tapered near the<BR>> ends. Is that so the panel will tend to move as = one unit and flex around the<BR>> perimeter - somewhat like a speaker = cone might move with its firm cone and<BR>> soft surround material that connects = the cone to the basket (I kinda don't<BR>> think this is really a good = analogy). It would seem to me that untapered<BR>> ribs are quite a departure = from "the proper way to build a soundboard".<BR>> <BR>> You do raise some interesting questions. It is my belief that ribs in the<BR>> 'modern' = piano are end-tapered the way they are to accommodate the practice<BR>> of compression-crowning. In this process the rib actually resists = the<BR>> formation of crown--i.e., the rib wants to remain straight but is = forced<BR>> into a curve by the stress interface created by the expanding = soundboard<BR>> panel. The rib must be kept to a reasonably consistent height and thickness<BR>> if the crown radius is going to be anywhere close to uniform.</DIV> <DIV> </DIV> <DIV><FONT color=#008000>Interesting. That sure does make a lot of = sense. Should work also.</FONT><BR><BR>> Even as most manufacturers began = converting from compression-crowning to<BR>> rib-crowning techniques (or some = combination of the two) the traditions of<BR>> rib sizing and feathering carried = over.</DIV> <DIV> </DIV> <DIV><FONT color=#008000>Hey man, we gotta do it like the masters!</FONT><BR><BR>> The problem, of course, comes at the = parameter where the tall ribs will<BR>> restrict the motion of the vibrating panel. = More or less--considering the<BR>> range of motion of the typical soundboard, = however, there really isn't a lot<BR>> of bending going on around the = parameter of the soundboard. So, in real<BR>> life, that untapered (un-feathered) rib may not matter all that much.<BR>> Indeed, it may = well help through the killer octave region.<BR>> ><BR>> > If = soundboards vibrate their various frequencies in small random<BR>> (seemingly) = areas of the board...<BR>> <BR>> Don't confuse reality with desirability. = Just because the typical soundboard<BR>> does break up into a myriad of miscellaneous resonances doesn't me this is<BR>> the ideal. Or that = this is desirable.<BR>> <BR>> > ...why do we taper ribs like we do (the = abrupt taper near the end). Why<BR>> not an even taper along the entire rib? = Or no taper?<BR>> <BR>> Why not indeed. Have you ever seen the ribs on = one of our soundboards? It's<BR>> been some years since we've feathered = anything in the conventional manner.</DIV> <DIV> </DIV> <DIV><FONT color=#008000>No I have not. I have seen the Walter grand - = but I don't remember the rib tapering. I'll just have to see your stuff = sometime! Thank you for your thoughts.</FONT><BR><BR>> Del<BR>> = </DIV></BODY></HTML>