Action Elevations

[David Love]

Ric B:

I would choose hammer at 90 degrees to the string over the shank being
parallel to the keybed.  In practice, the string is not actually parallel
to the keybed.  It rises slightly as it moves toward the bridge.  Some
techs (Richard Davenport comes to mind) advocate a slight short bore so
that the hammer is at 90 degrees to the string at impact.  You could
accomplish the same thing raking the hammer inward slightly.  
Historically, this was sometimes done to accommodate shank deflection.  I
have encountered older pianos (Bechsteins, for example) where the string
heights were not only uneven, but were such that a bore of flange center
pin to string height distance would not allow the bass hammers to get
underneath the block.  In such cases I have bored all hammers the same and
adjusted the rake in each section to accomplish the 90 degrees at impact. 
It has produced no strange regulation compromises nor any compromise in
feel that I could detect.  It seems that this is how the hammers were
originally installed.  

I'm not sure I understand your second question.

David Love

> [Original Message]
> From: Richard Brekne <Richard.Brekne@grieg.uib.no>
> To: PTG <pianotech@ptg.org>
> Date: 1/20/2003 7:52:00 AM
> Subject: Action Elevations

...snip...

> So first... if you have to choose the lesser of two evils... what would
> you say is the right choice to make ? Keeping the hammer shank
> centerline parallel to the keybed at strike distance or hitting the
> strings at 90 degrees ?

...snip...

> Another question I am wondering about....
>
> If the center spread is to be viewed as a fixed value, and bore distance
> is fixed..doesn't that sort of dictate the height of the hammer shank and
> whippen centers over the keybed ?


> RicB