Keylead inertia and leverage (was Re: Ideal leading pattern:)

[Mike and Jane Spalding]

Ric,

This is one of those counterintuitive concepts:  how can more weight result
in less inertia?  The key (no pun intended) is in the leverage.  The closer
the weight is to the balance rail, the shorter the distance it moves during
a keystroke.  Less acceleration.  The closer the weight is to the balance
rail, the more leverage is available to the pianist to overcome the inertial
resistance.  These two leverage effects (less acceleration, more mechanical
advantage) combine to cause less resistance to be felt by the pianist.  If
you can struggle through the math of my earlier post, I think you'll see how
it all works out.

Mike

----- Original Message -----
From: Richard Moody <remoody@midstatesd.net>
To: <pianotech@ptg.org>
Sent: Monday, April 02, 2001 2:34 AM
Subject: Re: Keylead inertia and leverage (was Re: Ideal leading pattern:)


> ----- Original Message -----
> From: Mike and Jane Spalding <mjbkspal@execpc.com>
> To: <pianotech@ptg.org>
> Sent: Sunday, April 01, 2001 2:49 PM
> Subject: Keylead inertia and leverage (was Re: Ideal leading pattern:)
>
>
> >
> > So, in both cases, the force AT THE WEIGHT is equal to 4*A.  But the
> force
> > felt by the pianist, AT THE FRONT RAIL, is reduced by the leverage:
> For the
> > weight at 4", the force is reduced by 4" divided by 8", so the
> pianist feels
> > 2*A.  For the weight at 2", the force is reduced by 2" divided by
> 8", so the
> > pianist feels A.  Bottom line, the closer the weight can be placed
> to the
> > balance rail, the less inertial resistance the pianist will feel.
> >
> > Mike
> >
>     A key with 2 weights near the front rail can be made to require
> the same down weight as a key with 4 weights near the balance rail.
> The key with 4 weights is heaver than the key with two weights.  This
> should make it feel harder to press it down (accelerate it) exp on a
> ff  note.even though it still has the same down weight as the key with
> only two weights.  The weight is the same to move each key, but isn't
> more force is needed to accelerate the heavier key to the same speed
> as the lighter key if both keys have  the same balance ratio?   ---ric
>
>