Plate Flexing

[David Love]

The problem is that the bridge is pretty level all the way across.  So
if you lower the plate at the nose bolts (which actually isn't possible
because the picture was taken with the nose bolts at neutral) you would
have to lower the bridge, unless you built up the aliquots by a
considerable amount.  The dowels are all cut pretty evenly around the
perimeter.  The plate just warped.  My understanding is that during
certain periods at Steinway, plate warping was more of a problem that at
others.  

If you set the plate at neutral, as I mentioned earlier, that would
force a fairly severe change in elevation, and mass, of the bridge from
one end to the other.  What is the effect of that, I wonder.  The
difference would be over 12 mm from low tenor to upper treble unless you
could fool around with the plate and block at the treble end and raise
that.  Then, of course, you start creating problems with string height
and bore distance, etc., etc..  Maybe the correct answer in this case is
jut to bend the sucker down and the hell with it.  I believe Shirley did
make this one.  

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Farrell
Sent: Friday, May 20, 2005 3:10 PM
To: Pianotech
Subject: Re: Plate Flexing

How flat is the plate along the hitch pins? If that is fairly flat, then
you 
should simply be able to adjust nose bolts to get the plate where you
want 
it in that low tenor area. Is a string stretched across the bass notes a

similar height above the bass bridge? If there is, is there any problem
to 
simply lower nosebolts to position plate properly?

Maybe someone tried to "tighten" the nose bolts in the past?  (i.e.:
"what 
are those darn things for anyway?")

Shirley the piano was not manufactured that way!!!!!!!!!!!

Terry Farrell

> While taking off the plate bolts of a Steinway L (c1961) I noticed the
> plate coming up at the tail.  The photo shows a stretched string
between
> the agraffe and hitch at note 27 after removal of the bolts--no
movement
> in the treble, btw.  Before removing the plate bolts, the bearing
> measured plus 1o at this point.  Total amount of flex in the tail was
> about .75".  Interesting in that the bridge is fairly uniform height
and
> the plate is level along the stretcher.  If I were to recap the bridge
> to accommodate the plate in a neutral position, there would be a 14 mm
> difference between the height of the bridge at not 27 and note 88.
>
> While the plate clearly has sat this way for a long time, I'm not real
> crazy about bending it that much again.  Plate flexing on Steinways is
> common but I've always wondered what the upper limit is.  This seems a
> bit excessive.  This piano will not get a new soundboard
(unfortunately)
> but that wouldn't really solve the problem anyway.  It seems that the
> plate is warped.  The string height does dip somewhat at the top of
the
> treble (typical) and since I'm putting in a new block my thought is to
> raise that side of the plate a bit which would rock the plate down a
bit
> in the back (though not much), recap the bridges (all of them will
need
> to be done) to allow a lesser amount of flexing at the tail.
>
> Any other suggestions or comments would be welcome.
>
> David Love 


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