Private: Keylead inertia and leverage

[Richard Brekne]

Thought I'd move this into the private areana for a bit..

You mentioned a few times now that the pianist "feels" less "resistance" when
the weights are in close... wouldnt that kind of explain (in part) why I am able
to so often observe the difference in how the measureing process of uw and dw
behaves ???

btw I tried it again today.. and same thing... I get a smooth measurement with
leads in close.. and some kind of friction stop up with them out.

regards... the other ric... grin

Mike and Jane Spalding wrote:

> 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
> >
> >

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:Richard.Brekne@grieg.uib.no