Sohmer

[Farrell]

Newton has a good idea for going in from the top, but you can still do the string thing on the bottom. Make two blocks the same thickness (easiest approach) as the underside maple cap. Maybe try some double-sided sticky tape on blocks. Attach to soundboard bottom near two far edges between the same ribs. Stretch string. If blocks are same thickness (remember tape thickness!) as maple underside cap, if you have a gap, you have crown, etc. Remember to measure many, many places on board. You can also hold string tight between the maple cap and each end of the board. Sometimes the boards are "S" shaped and you might find for instance that a string stretched all the way across the board suggests no crown - flat board. But on one side of the bridge there is positive crown and on the other side of the bridge is negative crown. Believe me, soundboard do warp that way! I've got the thinnest sounding Bechstein to prove it!

Terry Farrell
  
----- Original Message ----- 
From: "Owen J. Greyling RPT" <greyco@kingston.net>
To: <pianotech@ptg.org>
Sent: Thursday, March 21, 2002 12:28 PM
Subject: Re: Sohmer


> Hi Robin,
> Could you elaborate on how you were able to measure the crown on your
> Sohmner?  I have a 7 foot, serial # 25512 model #11 in my shop, and am
> pondering how to measure the crown with that maple reinforcing strip in the
> way.  I don't think that this piano has any crown, but would love to hear
> your method.
> Thanks, Owen.
> ----- Original Message -----
> From: "Robin Hufford" <hufford1@airmail.net>
> To: <pianotech@ptg.org>
> Sent: Thursday, March 21, 2002 3:45 AM
> Subject: Re: Sohmer
> 
> 
> > Dale,
> >      I have a Sohmer 9B in the shop.  It has conventional crown which is
> > about 1/8 in the middle.  This is after restringing and being within 1/2
> > step of pitch.   I think these are great pianos and I like their bridge
> > agraffe system.  This particular Sohmer had a very pronounced long crack
> > running about an inch and a half or so in front of the bridge.  This
> > crack, which I have seen on several other Sohmers in virtually the same
> > configuration, is obvious stress relief from the forces produced by the
> > bridge operating and pulling on the board, that is, relief of shearing
> > stresses.  Usually, there is about an eighth of an inch or more of
> > offset in height between the two parts of the board where this occurs.
> >       In the one in the shop the ribs were dowelled to the board in this
> > area and the crack was filled with epoxy.  This crack is about the only
> > characteristic failure of  the c. 6 feet Sohmers with the agraffe system
> > I have seen, although, as I have seen perhaps, only 8 or 9 over the
> > years, this may be a generalization on shaky grounds. The factory,
> > apparently, was aware of this as they have attached on the botton side
> > of the board, under the bridge, a long reinforcing strip of maple, let
> > in and passing through the ribs. The crack occurs in front of this
> > strip.
> >      As to the agraffe termination at the bridge, I think this works
> > quite well and, is probably a better, but more expensive mousetrap.
> > Perhaps the expense is not that much more than the conventional method
> > but I would guess that it would be as the bridge requires, of course,
> > planing, notching of a somewhat different fashion,  the maple strip,
> > notching of ribs, AND an agraffe and its installation.  The ringtime of
> > this system seems distinctly superior to my ear in comparison to the
> > conventional method.
> > Regards, Robin Hufford
> >
> > Erwinspiano@AOL.COM wrote:
> >
> > >    Part 1.1    Type: Plain Text (text/plain)
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>