What matters most?

[Mark Davidson]

David,

I don't really disagree with you.  The question isn't really absurd (I just
spent most of my spare time this summer improving my own piano's touch).

And I agree that Stanwood's contributions are the best thing we've got
going.

But I guess my main point is that the ultimate goal w.r.t. touchweight is to
put a
certain amount of energy into the key and thereby accelerate the hammer to
some acceptable speed.  From the pianist's point of view it's about
acceleration and velocity.  Yet we never measure this.

Newton's equation of motion is

force = mass * acceleration, (or torque = inertia * angular acceleration)

Stanwood sets acceleration to zero. Then the forces neatly sum to zero.
He never measures inertia, acceleration, or energy in the system directly.
This does not make his system in any way invalid, but  he's still one
step away from what is, in my mind, the ultimate goal, which is tracking
where the energy from the pianist's fingers goes.

Consider another model:

1 The first 10 or so grams of force go into overcoming friction
2 The next 40 or so go into overcoming BW
3 All additional force goes into acceleration of key, wippen, and hammer.
The
   relative amounts of energy in each part depend on the inertias and speeds
   of each part.
4 Some minimum amount of speed is required at letoff for the hammer to
   continue on and strike the string producing a usable tone.

When measuring DW/UW, we add only enough weight to overcome 1 and 2.
Acceleration and velocity are never measured.

So here's the question: for a given setup, what is the terminal hammer
velocity for a 100g (or any other) DW?

When we can answer that I think we'll be a lot closer to the answer to
Richard's
original question.

-Mark

David Love wrote:
>The question may seem absurd to the pianist who doesn't even know the names
>of the parts, but it's certainly not absurd if the piano isn't performing
>well.  As technicians, we need to be able to quantify cause and effect as
>much as possible if we are to have any chance of producing a predictable
>action, soundboard, or anything else for that matter.
>
>With respect to this question, I think what we are likely to find, and have
>found (thanks in large part to David Stanwood), is that a certain weight at
>the hammer end works best with certain action ratios....