Keyleads and MOI

[Ed Sutton]

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Dear List-

This discussion of MOI in piano actions has been one of the great =
moments on this list.

Throughout this discussion I have been trying to find an answer to the =
question "How can I tell if it matters enough to do something about it?" =
and "Is there a point of diminishing return where we should stop =
worrying about key lead placement?"  As practicing piano technicians, =
this is the question we are all seeking to answer.

The act of playing a piano is so complex, the demands are so varied, and =
the techniques, sizes and shapes of people who do the playing are so =
varied, that while analysis of the physics of the action give us =
insight, I don't believe it can give final answers.

Ultimately the answers will have to come from empirical performance =
tests using real musicians.

I have been trying to think of some way to test this that doesn't =
require an immense budget and research lab, since I have neither!.

So I've done various thought experiments, looking for something =
feasible.

Here's the best I can imagine so far.  I would appreciate critical =
comments:

1) Start with a piano with a well designed and regulated action.  It =
should have strikeweight and frontweight continuities, even balance =
weight and friction as low and even as possible, and presumably wippen =
assist springs.  The keyleading should be as consistent from key to key =
as possible.

2) Add extra key leads to certain keys.  Add these leads in pairs =
equidistant from the balance pin hole, one lead to the front, one to the =
back.  In this way the measured parameters of frontweight and =
balanceweight should not change, but the MOI of various adjacent keys =
would be very different.  If, for example, one large lead is added, =
front and back at 8" from the balance pin hole, the relative MOI =
difference between keys will become greater from bass to high treble. =20

3) Have pianists play the piano and report on what they feel and how it =
influences their playing.  Compare their reports with actual locations =
of extra lead.=20

Thanks for your comments.

Ed Sutton

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