Even balance weight or even something else, that's the question.

[John Hartman]

David Love wrote:
> 
> Why do we assume that even balance weight should be the standard which
> translates to a lighter feel at the upper end of the piano than at the
> lower end.  Anybody experimenting or setting up pianos with a graduated and
> increasing balance weight or, better yet, with uniform inertia?
> 
> David Love
> davidlovepianos@earthlink.net

David,

As far as I know no one has created the tools or methods to calibrate an 
even gradation of inertia in an action. I think it would be difficult to 
use key leads to balance the action statically and dynamically at the 
same time.

Please refer to the illustration I have posted on my web site. If you go 
to the information page there is now a link to a page I have created for 
materials of interest to technicians. I have posted a drawing of how to 
measure the moment of force and the moment of inertia.

The greatest variation in inertia is found in the keys due to variations 
in the leading pattern. I suppose keeping the leading pattern as even as 
possible would provide a rough calibration of key inertia.

BTW both of these keys could have the same moment of force but the lower 
key would have a lower moment of inertia.

John Hartman RPT

John Hartman Pianos
[link redacted at request of site owner - Jul 25, 2015]
Rebuilding Steinway and Mason & Hamlin
Grand Pianos Since 1979

Piano Technicians Journal
Journal Illustrator/Contributing Editor
[link redacted at request of site owner - Jul 25, 2015]