Moment of Inertia of grand action parts.

[John Hartman]

Richard Brekne wrote:

> 
> One of the things we are going to end up needing is a very clear and
> simple way of measuring action MOI, comparing to a reference base ala
> Stanwoods Smart Chart... or something in the same spirit, and choose
> what hammer weights, ratio, and key leading will give us the particular
> performance characteristics we are after at any given time. 

Well Richard,

That would be nice but I don't think any simple process will come out of 
this adventure. I think getting the action reasonably accurate in terms 
of static balance is useful. It helps to make the action feel even at 
soft levels of play. Once the action is played with more force many more 
variables come into play and things become rather messy. To get the 
action to play from note to note perfectly evenly at loader levels we 
need to control things like the differences in key stiffness. Looking at 
the difference between the naturals and sharps I don't think that is 
going to be practical. I think the benefit to learning this stuff is in 
guidance with the relative importance of some of the thinks we do to 
actions. It will help to tell us what to pay attention to and what to 
leave alone.

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]