Ideal leading pattern:

[larudee@pacbell.net]

I stand corrected.  By the way, it is part of the principle of the Steinway
accelerated action design, right?

Paul

Mike and Jane Spalding wrote:

> Paul,
>
> I believe you are mistaken regarding the inertia.  (As a former machine
> design engineer who recently jumped out of the frying pan and into piano
> tuning, I have some experience with this).  It does indeed vary with the
> placement of the lead:  Putting less lead further out will result in more
> inertia than more lead closer in.  Half the weight, twice as far out, same
> static downweight, but twice the inertia.  (For those of us old enough to
> remember phonograph records, this is why the counterweight on the tone arm
> is very large and very close to the pivot point.)  Doesn't change your
> conclusion:  all other things being equal, keep the lead near the pivot
> point.
>
> Mike Spalding
>
> ----- Original Message -----
> From: <larudee@pacbell.net>
> To: <pianotech@ptg.org>
> Sent: Thursday, March 29, 2001 10:15 AM
> Subject: Re: Ideal leading pattern:
>
> > David,
> >
> > As a matter of simple physics, it makes no difference whether you put less
> lead
> > farther away from the balance rail or closer in, with one stipulation.
> The
> > stipulation is that the key is perfectly rigid and has no flexibility.
> > Otherwise, both the momentum and inertia will be the same either way.
> >
> > Of course, we know that the key is not perfectly rigid, so placement of
> more
> > lead closer in is probably preferable, all else being equal.  This reduces
> the
> > sense of inertia in the key because the part that takes the force of
> depression
> > has less mass in it than otherwise, and applies leverage to the part that
> has
> > the mass, closer to the balance rail, after some momentum has already been
> > gained in the key.  Along with the use of cylindrical key bearings, I
> think this
> > design is part of what Steinway calls its accelerated action, but I am
> prepared
> > to be corrected.
> >
> > Paul Larudee
> >
> > David Love wrote:
> >
> > > I run into this sort of situation frequently and I would like some
> opinions.
> > >   Steinway model S ca 1936.  I am replacing hammers and shanks only.  I
> use
> > > Steinway hammers full taper, Abel shank 16.5 mm knuckle gives me the
> best
> > > combination of regulation/downweight from which to work.  The strike
> weight
> > > is medium and consistent throughout.  Key weight ratio is 5.0.  When I
> > > install the hammers, I will still want to take 2-5 grams off the
> downweight
> > > throughout much of the piano (though it is somewhat erratic) to get a
> 52-48g
> > > taper.   Doing so does not compromise the upweight.  The present front
> > > weight of the keys allows me to add lead without exceeding the maximum
> > > recommended front weight (according to Stanwood charts).  But... the
> keys
> > > already have a fair amount of lead grouped mostly toward the balance
> rail.
> > > Though the front weight is not excessive, the keys themselves weigh a
> lot
> > > because of the amount of lead in them (e.g. C16 = 163g , C40 = 144g, C64
> =
> > > 133g).  I have the option of adding a small lead, or removing two or
> more
> > > large leads from near the balance rail and replacing them with one large
> > > lead out toward the front of the key.  The latter will produce a more
> > > conventional leading pattern--and involves a lot more work.
> > >
> > > My questions are:
> > >
> > > 1.  Which one will produce a better feel?
> > > 2.  Will the difference be significant?
> > > 3.  Do front weight parameters change with the overall length of the
> key:
> > > i.e., is the allowable front weight greater for a model D than for a
> model
> > > S, or there other factors.
> > > 4.  What additional information will be helpful in making a quantifiable
> > > decision?
> > >
> > > David Love
> > > _________________________________________________________________
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> >