[pianotech] Increasing bridge height

[David Love]

Just to add something here, in practice the string heights very somewhat
because of the curvature (or warping) of the plate not just because the
bridge height changes.  For the B I have in the shop at present the string
heights increase from low tenor to the break by 3 mm while the bridge height
decreases by 2 mm.  The string height then drops by about 5 mm by the time
you get to note 88 while the bridge height does the same.  If I move the
treble side of the plate relatively higher, then the difference between the
string height at the break versus the low tenor will increase.  My goal,
therefore is to have a bridge height which graduates from somewhere around
35 mm in the low tenor to around 30+ at note 88.  Because of the plate I
won't be able to bore the hammers uniformly if I want them to match center
to string height throughout the piano.  So I either custom bore each section
with a graduated bore distance point or live with the regulation differences
in each section (wouldn't be the first time).  Welcome to the wonderful
world of Steinway plates.     

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Will Truitt
Sent: Tuesday, March 24, 2009 3:08 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Increasing bridge height

Hi Ron:  

One question that has not been asked by me or anyone else is what changes
you are making to the height of the bridge other than in the high treble.
We are talking here about of Note 88 having a bridge height of  30 mm (Del
says elsewhere that 32 mm is ideal for the A-2 in question).  Are you making
the bridge height along its entire length the same height as in the  high
treble, or are you raising it by a corresponding amount along its length (as
in adding 5 mm. or whatever everywhere?).  Is there sufficient benefit to be
had by increasing  the bridge height along its length to merit doing so, or
is the bang for the buck best realized only in the treble? I would be
grateful if you would describe your method for the entire treble bridge for
the sake of clarity.  From your other comments, it sounds to me like you are
making it fairly uniformly one height.  

I understand what you are saying about the uniform height difference - the
Steinway string height tapers downward into the treble (in my A-2 the
highest point of the string height is at about note 51 at 195 mm., and note
88 is at 189 mm. - fully a 6 mm. difference!).  If I bore the treble hammers
to only one value, it seems a matter of choosing my poison - I am going to
be overcentering, undercentering, and just right depending on what note I am
on.  If all else is equal, it seems a candidate for a tapered bore, unless
there is some sublime mystery to Steinway's one size fits all boring that I
am missing here.

Will  



-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Tuesday, March 24, 2009 6:43 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] Increasing bridge height

Will Truitt wrote:

> I am guessing that what you are saying her is that your practice of
raising
> the bridge is essentially the same as Del's, but I am not sure what you
are
> trying to say about the string plane in the upper treble (although I know
> that the string height tapers down as you progress into the treble in
> Steinways, if that is what you are referring to).  I don't know what you
are
> referring to with "works out fine".  Please explain a bit more fully.

With the string height closer to uniform throughout the tenor 
and treble, the height difference between the shank center and 
strike point on the string will be more uniform than in the 
original. So you're not creating more problems elsewhere in 
making the treble end of the bridge taller, you're at least 
somewhat correcting something (of the many)  that shouldn't 
have been there in the first place.


> I take your comments about the stack and bore to mean that you are boring
> the tenor and treble hammers to one measurement, albeit one that reflects
> the 4 or 5 mm higher string height, yes?

Yes, except only the high treble changed 4-5mm.
Ron N