The Steinway Bell Bolt/ How tight

[Bill Ballard]

At 2:16 PM +0200 9/17/02, Richard Brekne wrote:
>>PIANO2NR@aol.com wrote:
>>
>>Does anyone know how tight the bolt that goes through the bell is 
>>supposed to be?  Finger tight plus 1 full turn?
>
>That is nearly exactly the word I got from the head of S&S Hamburgs 
>technical support section just a couple weeks ago.
>
>But then he also mentioned that a bit tighter was ok too as long as 
>it increased sustain. I would be real carefull about tightening this 
>myself without having some way of knowing just how much the plate 
>was being stressed.


I remember bringing up the subject in June of 98. Rick Davenport's 
story about Heiner Seinwald (?), the Fazioli tech, working a miracle 
on a piano in Rick's shop (not a Fazioli). Don Mannino's contribution 
to this thread was, "I would be hesitant to do what Heiner does 
without knowing what he knows".

Knowing how much the plate is stressed requires knowing where it lies 
flat before the bolt begins to deform it. In a plate with a tension 
load, that's not reliably readable.

I remember Jim Coleman remarking that such a maneuver was not likely 
to remedy slim or negative downbearing because the board would squash 
to return the downbearing pressure to the pre-maneuver level.

But that bolt can definitely stiffen up the plate web, which is what 
I gather Heiner was sensing with his finger tips.

Bill Ballard RPT
NH Chapter, P.T.G.

"I gotta go ta woik...."
     ...........Ian Shoales, Duck's Breath Mystery Theater
+++++++++++++++++++++