Inertia

[Michael Wathen 556-9565]

Ken Sloane left this message:


    Mike at Cincinnati: The rationale for my saying that not much
    information is derived about inertia by using touchweights while
    measuring acceleration in a key/ham system came in the next
    sentence, though (I must admit), I didn't make that very clear.
    Let me be more thorough.

    I said in that next sentence: "Pianos I have encountered with lots
    of inertia seem to be fine for the pianists until they play them
    fast and loud. At that point, all the inertia in the piano becomes
    a problem for the pianist as they try to accelerate/decelerate the
    key/hammer  systems very quickly many times persecond". In other
    words, I don't think we would see much difference in acceleration
    rates between pianos of high and low inertia until we tried to
    accelerate them -- i.e. their key/hammer systems -- very quickly
    as occurs in fast, loud playing.

I've been thinking about this over the last several days.  The purpose
of wanting to look at angular accleration is for my diagnostic
purposes.  My experience is frustration with mostly Steinway actions
that have been retrofitted with new parts.  You can achieve good
Weight and Friction values and still have an action that is
unsatisfactory.  If I think back over the last 12 years here I have to
admit that there are just as many complaints about actions that are
too easy to play as there are about ones that are difficult.

Ken:
    We have to invent some sort of spring loaded machine that could
    engage notes rather forcefully but, of course, at the same force
    from piano to piano to analyze inertia because its presence, as
    it relates to the pianist in a problematic way, is not felt on
    soft blows. Obviously the touchweights mimic a softer than soft
    blow.

Let me point out that accleration is entirely independent of the
speed.  This means that using the method I described in my original
post it will not matter what gram weight I use to make my
measurements.

Michael Wathen
College-Conservatory of Music
University of Cincinnati