Plate Flexing

[David Love]

Of course, it's difficult to lay the plate on a flat table, but with the
plate laying flat against the pinblock and the nose bolts turned down so
they don't rest against the underside of the plate at all, the plate
lays flat on the dowels in the treble and for a ways down along the bent
side.  It starts to come up off the dowels about half way around.  When
you get to the bass end, the plate is off the dowels by, as I said,
between 1/2 - 3/4", depending on how you measure.  The dowels themselves
are fairly consistent in height all the way around, not varying by more
than a mm or two.  Since I am replacing the block (haven't removed it
yet) and recapping the treble bridges I, and since the string height
dips a bit in the upper end, I may raise the plate slightly at the
treble end which will tilt the plate slightly downward at the bass end.
Not enough to avoid bending it down again, but a little bit.  Replacing
the perimeter bolts with set screws might make it easier to tweak things
as well, but since the plate requires bending to set the height of the
lock nut underneath, it becomes a little awkward to do that.  I'd have
to use a clamp and a block of wood (something like you use to clamp the
soundboard down for gluing) to bend the plate into position and then set
then turn the set screw up or down as needed.  

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Farrell
Sent: Saturday, May 21, 2005 2:23 AM
To: Pianotech
Subject: Re: Plate Flexing

I may not be understanding the situation clearly here, so please bear
with 
me. If you lay the plate down on a flat table, is the plate flat or can
you 
see that it is warped?

What do you mean that the nose bolts are neutral? I presume you mean
that, 
with the plate bolts removed, the hitch pin edge of the plate is resting
on 
the rim dowels (or at least some of them) and just touching the base of
the 
nose bolts? With the plate bolts removed, is the plate perimeter resting
on 
all the dowels, or is it up off the dowels in the bass/tenor? I'm 
envisioning that the plate rests on dowels in the treble area, the nose 
bolts everywhere, but is raised up above the dowels in the bass. If that
is 
the case, then I should think you could just lower the nosebolts, maybe 
trim/lower a few of the low treble dowels a tad and be back in business.

How flat is that plate?

You need to hear from Del Fandrich or Ron Nossaman for a good opinion on
the 
effect of added bridge height. I know one time I thought I needed to
make 
one a little shorter than normal and they both advised against it -
however, 
maybe a little added mass in that area is not such a detrimental thing.

Terry Farrell


> 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 


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