Virtual Capstan

[Mark Davidson]

This was my initial reaction.  You do less work at the front
of the key but the same amount at the back of the key.  How's that possible?
Yet he's got the experimental data to show it works.

I think the answer lies in that fact that the magnets, like a spring, have
stored energy
that is released as the wippen and key move apart which does some of the
work.
This energy is stored again as the parts move back together.  It wouldn't
work
if the distance between the parts were not changing.

Not exactly intuitive, but really cool!

-Mark

----- Original Message -----
From: "Bill Ballard" <yardbird@vermontel.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Saturday, June 21, 2003 11:17 AM
Subject: Re: Virtual Capstan


> At 12:35 AM +0200 6/20/03, Richard Brekne wrote:
> >The whippen assist spring simply makes the whippen lighter by
> >pulling up against it from the whippen rail. This really does
> >something quite different. It provides a secondary support for the
> >weight of the action very much in the same sense that the
> >capstan supports the action weight.
>
> Under Newton's Third Law (Action and Reaction), the support for the
> force opposing the lifting of the spring is the action frame. Under
> your scheme, the support for the force opposing the magnets is the
> pianist's finger and hand. It doesn't sound as though the forces
> encountered in playing this action have been reduced by transferring
> them to something outside of the system of parts in motion (pianist
> included). But if you don't intend to counterbalance more than 5g of
> BW, this could be negligible.
>
> Bill Ballard RPT
> NH Chapter, P.T.G.
>
> "I gotta go ta woik...."
>      ...........Ian Shoales, Duck's Breath Mystery Theater
> +++++++++++++++++++++
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives