Sohmer

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: March 15, 2002 10:56 PM
Subject: Re: Sohmer


> >
> >Are you sure those were reverse crown by design? Those I've done had
positive crown. And extremely high scale tensions -- highest I've ever
measured. Around 62,000 lbs (28,000 kgf +) or better as I recall. Took some
doing to bring it down and retain the agraffe design (as per the customers
request).
> >
> >Del
> >
>
> Del,
> I somehow lost a previous post in which you said you had re-engineered
(right
> word?) several of these pianos.  Does that mean that you eliminated the
agraffes on
> the bridge?  If so, why?  Here you talk about bringing down the tension
and
> retaining the agraffes.  I don't see what difference it makes to the scale
whether you > have agraffes or bridge pins.  Could you elaborate on that a
bit?

With the Sohmer's I've left the agraffe bridge arrangement. It's one of the
few of its type that has held up well over the years. I'm not sure what has
made the difference. Perhaps it's the length of the agraffe--the threaded
portion of which extends nearly all the way through the bridge--or it may be
the maple reinforcing bar mounted on the backside of the soundboard
paralleling the bridge. Whatever it is, among the agraffe bridge systems the
Sohmer is unique; it seems to work quite well.

To reduce the string tensions I sectioned the bridge at the plate brace gaps
and staggered the individual pieces to reduce the tensions to some
reasonable level. I dry fitted the individual bridge sections on to the
soundboard template, made little gap spacers to fill in the saw kerfs and
splined them back together. This did stagger them a bit so I rounded
everything off a bit and cleaned them all up so they would look pretty and
sprayed them with lacquer after they were mounted on the new soundboard.

No, it makes no difference in terms of scaling whether agraffes are used or
bridge pins are used. The agraffe bridges are a bit tricky to work with when
it comes time to establish string bearing because of the vertical string
offset but sketching things out on paper helps.

Most other agraffe bridges automatically get replaced with conventional
bridge work simply because they have all shown a tendency to self-destruct
over the years. But not the Sohmer system. At least not those I've seen.

Del