----- 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
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