A not so boring, boring dilemma

[Jon Page]

At 07:11 AM 4/9/2002 -0400, you wrote:
>One effect of changing a bore distance is the differences in
>regulation.  Shortening the bore will raise the let-off, the drop and
>change the capstan location.  I should suggest boring several hammers of
>different sizes at the angles you suggest and try the regulation and see
>how it feels.
>
>Feel is the ultimate criteria.
>
>                 Newton

Last year I installed a set on and old Bechstein. I encountered the same 
measurements in regards to the hammer
length and angle. Resign yourself to the fact that you will not achieve a 
90 degree pitch and length close to
'hammer flange center to string' difference.

Calculate the longest hammer length attainable by considering what length 
will allow the action to slide in under the
pin block and have the shanks off the rail.  The angle will have to be wide 
to get the hammers to hit the strings squarely.
here's what I have recorded for hammer length between the sections:
2 1/4 , 2 1/4  \  2 1/16, 2 1/8  \  2 1/8, 2 1/16  \  2, 2

The only angle I have recorded is for the top section which is 3 degrees to 
2 degrees.  The rest were greater than 8 degrees
as I recall.  Bore a few samples to your calculations and fit them on the 
shanks, the ends of each section.  Lift the hammer to the
strings and check it's attitude with a square.  Once this is ascertained, 
check strike point.  Angle the hammer back just a
little more to allow for hammer wear because as the hammer becomes shorter, 
the angle decreases.  Install your trials and
check strike point and regulation.

Don't make the tenor/treble hammers longer than what would be proportional 
to the bass section, regulation difficulties will develop.
So fit the bass hammers to the strings/pinblock allowance and bore the 
treble hammers a proportional distance, that is the difference
between the bass string height and tenor string height and their respective 
sections.

Fortunately the piano was also being relocated at the time and it went to 
my shop, which saved a lot of running back and forth for these fittings.

The action played fine and has been functioning without complaints. BTW, 
the friction on these rocker arm, sticker actions is lower
than the modern configuration.

Regards,

Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@attbi.com
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