<HTML>In a message dated 2/2/2003 7:13:40 AM Pacific Standar= d Time, Erwinspiano writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Subj: Re: Bearing difference on different soundboards </= B> Date: 2/2/2003 7:13:40 AM Pacific Standard Time From: <A HREF="mailto:Erwinspiano">Erwinspiano</A> To: <A HREF="mailto:oleg-i@wanadoo.fr">oleg-i@wanadoo.fr</A> In a message dated 2/2/2003 = 4:13:49 AM Pacific Standard Time, oleg-i@wanadoo.fr writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Subj: Bearing difference on = different soundboards Date: 2/2/2003 4:13:49 AM Pacific Standard Time From: <A HREF="mailto:oleg-i@wanadoo.fr">oleg-i@wanadoo.fr</A> To: <A HREF="mailto:caut@ptg.org">caut@ptg.org</A> Sent from the Internet Hello Issac</BLOCKQUOTE>      <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000= ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"></FONT= >Hello, I understand recently that w= e probably don't have to apply down bearing the same way on a rib crowned so= undboard and on a "compression crowned" board, as the last one will do it's = best under a light load, while the crowned rib bar ask for the down bearing = to give them some more internal tension. >>I think yes and no. I use the same methods of setting bearing on= both but the CC  boards are old with little crown and the Rib crown bo= ards are new &have plenty and are stronger. </BLOCKQUOTE>        One basic rule is not to apply more = bearing than crown. If 1/4 <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">inch of crown is present in = either kind of board design, for example on the longest ribs, then any dista= nce bearing at the string rest should not exceed 1/4 inch or so.  It's = OK to press the board to the flat position with the bearing,which is obvious= to me that Steinway and others routinely did, but not beyond.   <= BR>   T</BLOCKQUOTE> his can be a problem if = your method of setting bearing does <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">not take into account how sw= ollen the board is at the time your setting bearing/bridge heights. I have c= ommonly seen 1920's S&S boards that still had uniform &graduated bea= ring but the board is sunk below flat. So What happened? </BLOCKQUOTE>     <F= ONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY= ="SANSSERIF" FACE="Arial" LANG="0">If The board is on the dry side = (EMC) when bearing is set the crown <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">shrunk down. Go easy on the bea= ring load for the load will increase naturally with the soundbds moisture ab= sorption and to much pressure will cause increase panel compression which br= ings early wood fiberdestructosis. (my word grin).</BLOCKQUOTE>     In a rib crown board I wish to be = conscious of EMC levels as well but its not as critical. I like to run damp = chasers under the board from the moment its glued to the case to stabilize E= MC. I have less to worry about and less guess work. Make sense? That being said A rib crowned board is ever so much stronger and my sense o= f it from others as well as myself that RC boards can handle a stiff load.<B= R>   All that said I like to check bearing and sound board squash as the t= enor is strung. We string up to pitch. This way when I get to the treble I c= an make sure of the residual bearing and make any fine adjustments at that t= ime. I.e. shim the string rest, adjust the nose bolts a squeak etc. <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">That makes a big difference in approach I guess.</BLOCKQUOT= E> >>Yes, If a flat b= oard is reused it still needs some nominal bearing (2mm) but it doesn't' rea= lly help much because a flat board is very flaccid and flexible except in th= e top trebles. <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> A friend of mine use to fine= regulate down bearing pressure with the string's rest height while stringin= g, checking with the strings at pitch as he goes.</BLOCKQUOTE> >>>>With the = strings chipped up to pitch I like to check my final bearing with the Lowell= down bearing gauge. I want to see 5 to 6 lines of movement or .015 to.018 o= f residual bearing in the middle portions on a fully crowned RC board. More = is seen in the top treble and less in the low tenor. I like some bearing at = the top of the bass bridge tapering down to basically o in the low bass espe= cially on cantilevered bridges.   We don't make CC boards. <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> Do some of you apply this me= thod ? Isaac OLEG Entretien et r�paration de pianos. PianoTech 17 rue de Choisy 94400 VITRY sur SEINE FRANCE tel : 033 01 47 18 06 98 fax : 033 01 47 18 06 90 cell: 06 60 42 58 77 <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT= : 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">----- </BLOCKQUOTE> </BLOCKQUOTE> </BLOCKQUOTE> </HTML>