Leverage and Dip

[David Love]

No, changing the spread does change the ratio.  The wippen is a lever as
well (though a different class of lever than the key, for example).  The
farther away from the flange that you lift it, the greater the mechanical
advantage.  When you increase the spread you are increasing the "wippen in"
dimension which lowers the ratio.  There was an example of this awhile back
when Newton Hunt traveled to South America? to help solve a weight problem
on a Yamaha.   He was able to achieve a reduction in weight, lowering the
ratio by increasing the spread.

David Love


----- Original Message -----
From: "Isaac OLEG" <oleg-i@wanadoo.fr>
To: "Pianotech" <pianotech@ptg.org>
Sent: October 03, 2002 9:45 PM
Subject: RE: Leverage and Dip


That is why action spread changes are not so much changing the overall
ratio in terms of weight or distance, mostly the friction and magic
lines off more or less ?

Isaac O



> -----Message d'origine-----
> De : pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org]De la
> part de David Love
> Envoyé : vendredi 4 octobre 2002 01:24
> À : Pianotech
> Objet : Re: Leverage and Dip
>
>
> The simplest way to look at this is with a teeter-totter.
> With fulcrum
> centered there is a 1:1 relationship with weight placed at
> either end,
> 100lbs will balance 100lbs and the arc scribed at one end
> will be duplicated
> at the other end.  Move the fulcrum so that one side is
> twice the length of
> the other.  Now, 100lbs on the shorter end will be balanced
> by 50 lbs at the
> end twice its length, and the arc scribed by the short end
> will also be 1/2
> of the arc scribed by the long end.  The 2:1 relationship
> is maintained both
> in terms of force leverage and distance leverage.  Though a
> piano consists
> of 3 levers, the overall relationship of input to output
> doesn't change.  At
> least that is my understanding.
>
> David Love
>
>
> ----- Original Message -----
> From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: October 03, 2002 2:31 PM
> Subject: Re: Leverage and Dip
>
>
> Before we go on... :)  could we resolve what seems to be
> two mutually
> exclusive standpoints here ?
>
> Bill Ballard wrote:
>
> > The problem is of course that there is no direct
> correlation between
> > action leverage as measure by distance and by weight.
>
> David Love writes:
>
> >The action ratio not only refers to the relationship
> between change in
> >weight at the hammer and the resultant change in weight at
> the key, it
> also
> >refers to the relationship between key travel and hammer travel...
>
> snip snip.....
>
> >At a ratio of 6:1, for example, 10 mm of dip
> >will result in the hammer traveling a total of 60 mm.  (It
> also means
> that a
> >change in 1 gram at the key will result in a change of 6
> grams in the
> >balance weight.)
>
>
> I dont mean to be a pain or anything... but you two seem to
> be saying
> exactly the opposite about this, and its kind of a central point.
>
> Thanks to both of you for some good reading... Its late and
> I have been
> putting in 18 hour days this last week... so I will re-read both
> tommorrow and get back to you.
>
>
> Cheers
>
> RicB
> --
> Richard Brekne
> RPT, N.P.T.F.
> UiB, Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
>
>
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