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

[John Hartman]

Richard Brekne wrote:
> 

> I would be very interested indeed in hearing how one would achieve uniform inertia
> in the action while at the same time being able to vary hammer mass from bass to
> treble. I suppose you had somthing in mind ?

I don't' think you can get an even inertia in the 
action from bass to treble unless you make the 
hammers the same mass. Or compensate for the mass 
difference somewhere else. I don't think getting 
the action to have the same inertia in the bass 
and treble is the point. Getting it even from note 
to note and not making it excessive would be the 
objective.

> 
>>>John Hartman Wrote:
>>
>>>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.
>>
> 
> Isnt "balance"  rather <<by definition >> a static measurement ? Would you be so
> kind as to expound a bit on what a "dynamic balance" is exactly ?...
> 

Dynamic balance relates to measuring and adjusting 
the inertia of an abject in rotation. You can 
statically balance a car wheel for example and it 
will run smooth at low speeds. You need to balance 
it dynamically if you want it to run smoothly at 
higher speeds. Inertia takes over when a body is 
accelerated faster than gravity (16 ft per second 
squared?). When we play the piano action most of 
time we are moving the parts in the dynamic range.

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]