Key Leads and Inertia

[Classic Touch Ent]

Greetings Richard and Don and all interested,

While the example given states a relationship regarding inertia and the 
effect of weight a given distance from the 'fulcrum', it seems somewhat 
removed from my real world experience.
How many pianos have weights placed one cm from the fulcrum? See 
http://www.stanwoodpiano.com/Pa100088web.jpg . (I.m guessing the lead 
closest to the balance pin (fulcrum) is 7- 10 cm away.)
That aside, at any given distance, how much assistance does a weight or 
weights give the pianists finger moving the 'stack mass' (which is say 
11 cm on the other side of the fulcrum)? and at what velocity? and 
finally at the location of the pianists on the key lever? Doesn't the 
distance of the pianists finger from the fulcrum mitigate the 
effectiveness of weights either fore or aft of the point of finger 
contact (and at differing rates of effectiveness for differing 
velocities)? Isn't it interesting that the pianists finger position is 
(by necessity or choice) variable? Richard Brekne, the name of your 
pharmicist/drug store (do they deliver to the US) please.

Best, Rich Olmsted

On Wednesday, April 30, 2003, at 08:33 PM, Don wrote:

> Hi Richard,
>
> The inertia goes up by the *square* of the distance from the 
> fulcrum--so
> yes three weights would likely have less inertia than *one* farther 
> from it.
>
> Run the numbers
>
> 30 grams x 1 cm from fulcrum = 30
How many pianos have weights placed one cm from the fulcrum? Of any of 
my grand pianos the closest weight is 10 cm from the balance pin. Also 
See http://www.stanwoodpiano.com/Pa100088web.jpg . I.m guessing the 
lead closest to the balance pin (fulcrum) is 7- 10 cm away.
 From what I have observed the 30 grams nearer the fulcrum might more 
likely be (3) 10 gram weights spaced over a distance, say 7- 12   from 
the balance pin (not in the same location & each having a different 
effect).
>
> 10 grams x 3 cm from fulcrum = 90
>
> If I'm wrong please let me know *grin*.
>
> Regards,
> Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.
>
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