---------------------- multipart/mixed attachment --part1_140.96b1111.2b6f4f9f_alt_boundary In a message dated 2/2/2003 7:13:40 AM Pacific Standard Time, Erwinspiano=20 writes: > Subj: Re: Bearing difference on different soundboards=20 > Date: 2/2/2003 7:13:40 AM Pacific Standard Time > From: <A HREF=3D"mailto:Erwinspiano">Erwinspiano</A> > To: <A HREF=3D"mailto:oleg-i@wanadoo.fr">oleg-i@wanadoo.fr</A> >=20 >=20 >=20 > In a message dated 2/2/2003 4:13:49 AM Pacific Standard Time,=20 > oleg-i@wanadoo.fr writes: >=20 > >> Subj: Bearing difference on different soundboards=20 >> Date: 2/2/2003 4:13:49 AM Pacific Standard Time >> From: <A HREF=3D"mailto:oleg-i@wanadoo.fr">oleg-i@wanadoo.fr</A> >> To: <A HREF=3D"mailto:caut@ptg.org">caut@ptg.org</A> >> Sent from the Internet=20 >>=20 >>=20 >> Hello Issac >=20 >=20 > >> Hello, >> =20 >> I understand recently that we probably don't have to apply down bearing=20 >> the same way on a rib crowned soundboard and on a "compression crowned"=20 >> board, as the last one will do it's best under a light load, while the=20 >> crowned rib bar ask for the down bearing to give them some more internal=20 >> tension. >> >>I think yes and no. I use the same methods of setting bearing on both=20 >> but the CC boards are old with little crown and the Rib crown boards are= =20 >> new &have plenty and are stronger.=20 >=20 > One basic rule is not to apply more bearing than crown. If 1/4=20 > >> inch of crown is present in either kind of board design, for example on= =20 >> the longest ribs, then any distance bearing at the string rest should not= =20 >> exceed 1/4 inch or so. It's OK to press the board to the flat position=20 >> with the bearing,which is obvious to me that Steinway and others routinel= y=20 >> did, but not beyond. =20 >> T > his can be a problem if your method of setting bearing does=20 > >> not take into account how swollen the board is at the time your setting= =20 >> bearing/bridge heights. I have commonly seen 1920's S&S boards that still= =20 >> had uniform &graduated bearing but the board is sunk below flat. So What=20 >> happened?=20 >=20 >=20 > If The board is on the dry side (EMC) when bearing is set the crown=20 > >> shrunk down. Go easy on the bearing load for the load will increase=20 >> naturally with the soundbds moisture absorption and to much pressure will= =20 >> cause increase panel compression which brings early wood=20 >> fiberdestructosis. (my word grin). >=20 >=20 > In a rib crown board I wish to be conscious of EMC levels as well but=20 > its not as critical. I like to run damp chasers under the board from the=20 > moment its glued to the case to stabilize EMC. I have less to worry about=20 > and less guess work. Make sense? > That being said A rib crowned board is ever so much stronger and my sense= =20 > of it from others as well as myself that RC boards can handle a stiff load= . > All that said I like to check bearing and sound board squash as the teno= r=20 > is strung. We string up to pitch. This way when I get to the treble I can=20 > make sure of the residual bearing and make any fine adjustments at that=20 > time. I.e. shim the string rest, adjust the nose bolts a squeak etc. >=20 > >> That makes a big difference in approach I guess. >=20 >=20 > >>Yes, If a flat board is reused it still needs some nominal bearing (2mm= )=20 > but it doesn't' really help much because a flat board is very flaccid and=20 > flexible except in the top trebles. >=20 > >> =20 >> A friend of mine use to fine regulate down bearing pressure with the=20 >> string's rest height while stringing, checking with the strings at pitch=20 >> as he goes. >=20 >=20 > >>>>With the strings chipped up to pitch I like to check my final bearing=20 > with the Lowell down bearing gauge. I want to see 5 to 6 lines of movement= =20 > or .015 to.018 of residual bearing in the middle portions on a fully=20 > crowned RC board. More is seen in the top treble and less in the low tenor= .=20 > I like some bearing at the top of the bass bridge tapering down to=20 > basically o in the low bass especially on cantilevered bridges. > We don't make CC boards.=20 >=20 > >> =20 >> Do some of you apply this method ? >> =20 >>=20 >>=20 >> Isaac OLEG >>=20 >> Entretien et r=E9paration de pianos. >>=20 >> 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=20 >>=20 >>=20 >> >>> ----- >>>=20 >>=20 >=20 --part1_140.96b1111.2b6f4f9f_alt_boundary An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/caut.php/attachments/f6/97/83/fb/attachment.htm --part1_140.96b1111.2b6f4f9f_alt_boundary-- ---------------------- multipart/mixed attachment An embedded message was scrubbed... From: Erwinspiano@aol.com Subject: Re: Bearing difference on different soundboards Date: Sun, 2 Feb 2003 10:13:40 EST Size: 15323 Url: https://www.moypiano.com/ptg/caut.php/attachments/cf/75/f5/95/attachment.eml ---------------------- multipart/mixed attachment--
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