MOInertia

[Isaac sur Noos]

John,

I am looking for the drawing and can't find it, could you please post
it again ?

Thanks.

Isaac OLEG

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Isaac OLEG
accordeur - reparateur - concert
oleg-i@noos.fr
19 rue Jules Ferry
94400 VITRY sur SEINE
tel: 033 01 47 18 06 98
fax: 33 01 47 18 06 90
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> -----Message d'origine-----
> De : caut-bounces@ptg.org [mailto:caut-bounces@ptg.org]De la part de
> John Hartman
> Envoye : mercredi 31 decembre 2003 23:57
> A : College and University Technicians
> Objet : Re: MOInertia
>
>
> Richard Brekne wrote:
>
> > I've asked this point on two occasions already and we
> havn't gotten
> > really into the point. Its one thing to point out the
> individual MOI of
> > the parts as John, and others have done. But how these
> turn out after
> > leverage is figured would be another thing. If it came
> anywhere close to
> > the roughly 5:1 ratio figure... then suddenly the Hammer
> and Shank MOI
> > become reduced by a factor of 5 and we are talking a
> whole different
> > degree of significance for the key MOI.
>
>   Richard,
>
> I thought I sent a drawing with how the leverage effects
> the MOI of the
> parts in the action chain? If you didn't see this I can
> send it to you
> off-list. The leverage that effects the MOI is different than the
> leverage that effects static balance. With MOI the angles
> that the wip
> and shank go through in relation to the angle the key
> travels is what is
> used.
>
[link redacted at request of site owner - Jul 25, 2015]
> >>
> >>
> >>     Key MOI = 10,307 gmcm^2
> >>     Wippen MOI = 3149 gmcm*2
> >>     Hammer and shank MOI = 165,528 gmcm*2
>
> These figures are adjusted for the reflected MOI in
> relation to the key.
> If you add these all together they are the MOI of the
> action. The total
> MOI controls how the action responds to a force applied to
> the front end
> of the key. In particular how much acceleration the front
> end of the key
>    will achieve in relation to a given force.  In a loose
> sense the MOI
> is to action dynamics what balance weight is to static balance.
>
> John Hartman RPT
>
> John Hartman Pianos
[link redacted at request of site owner - Jul 25, 2015]
> Rebuilding Steinway and Mason & Hamlin
> Grand Pianos Since 1979
>
> Piano Technicians Journal
> Journal Illustrator/Contributing Editor
[link redacted at request of site owner - Jul 25, 2015]
>
>
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