Even balance weight or even something else, that's thequestion.

[David Love]

I think it is a slight misstatement to say the uniform balance weights
produce uniform feel.  I agree that the balance weight system is far
superior to the down weight system.  I wasn't arguing for using the down
weight when balancing an action.  I routinely use the balance weight as the
standard.  That being said, setting the balance weights equal produces a
smooth curve from bottom to top, not uniformity from bottom to top.  The
differences, exist as a result of declining friction, declining strike
weights, and declining front weights.  My question came up as a result of a
customer whose piano (balanced with equal balance weight) felt lighter to
her at the top.  And, in fact, it does feel lighter at the top for the
reasons just mentioned.  In her case, this was not desirable.  Une
hirondelle ne fais pas le printemps, as they say in France (one swallow
does not make the spring), it is only one case and I am not necessarily
trying to draw conclusions for all pianists.  But it did give rise to the
question as to whether a graduated balance weight will not produce a more
uniform feel.  That is what I ended up doing and to her satisfaction. 
Since the upper end of the piano feels lighter due to reduced friction and
other factors previously mentioned, in order that it should feel more like
the lower end of the piano you might need a higher balance weight at the
top than the bottom.  It wouldn't necessarily destroy your smooth curve. 
You would still have a smooth strike weight curve, a smooth front weight
curve (unless you are not a licensed installer, in which case you would
have to settle for a quasi smooth curve), and now, a smooth balance weight
curve progressing upward at, say, the same rate as the friction decreases. 
Just an idea.

As for Richard Brekne's question, did I have something in mind when I
suggested using inertia, or a dynamic model.  I can't say that I have a
specific idea.  I don't really know how to handle the inertia question in a
quantifiable way--not yet anyway.  There are those who are working on the
project, though, and it will be interesting to see what comes of it.  I am
reminded, however, of a presentation I saw some years ago by Rich
Baldessin.  In short, he had a customer who complained of an action that
was too light.  Taking lead out of the keys did not seem to solve the
problem adequately.  Anyway, to make a long story short, he found that in
order to satisfy the customer, what was needed was to add two leads, one
behind the balance rail and one in front, equidistant from the center.  The
net effect on the balance weight would have been zero, but the, presumably,
increase in inertia was what the pianist was looking for.  So, my thought
was that in order to compensate for the decrease in hammer weight and front
weight as you proceed up the scale, all of which subtract from inertia, a
graduation from front leading to a combination of front and back leading,
might lead to a more uniform sense of inertia in spite of the apparent
obstacles.  Then again, it might be much ado about nothing.

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: David C. Stanwood <stanwood@tiac.net>
> To: <pianotech@ptg.org>
> Date: 4/21/2003 11:18:24 AM
> Subject: Re: Even balance weight or even something else, that's
thequestion.
>
> >David Love wrote:
> >> 
> >> Why do we assume that even balance weight should be the standard which
> >> translates to a lighter feel at the upper end of the piano than at the
> >> lower end.  Anybody experimenting or setting up pianos with a
graduated and
> >> increasing balance weight or, better yet, with uniform inertia?
> >> 
> >> David Love
> >> davidlovepianos@earthlink.net
>
> >John Hartman Wrote:
>
> >David,
>
> >As far as I know no one has created the tools or methods to calibrate an 
> >even gradation of inertia in an action. I think it would be difficult to 
> >use key leads to balance the action statically and dynamically at the 
> >same time.
> >
> >Please refer to the illustration I have posted on my web site. If you go 
> >to the information page there is now a link to a page I have created for 
> >materials of interest to technicians. I have posted a drawing of how to 
> >measure the moment of force and the moment of inertia.
> >
> >The greatest variation in inertia is found in the keys due to variations 
> >in the leading pattern. I suppose keeping the leading pattern as even as 
> >possible would provide a rough calibration of key inertia.
> >
> >BTW both of these keys could have the same moment of force but the lower 
> >key would have a lower moment of inertia.
> >
> >John Hartman RPT
> >
> >John Hartman Pianos
[link redacted at request of site owner - Jul 25, 2015]
>
> Dear David and John,
>
> I'll pitch in my boiled down take on this subject:
>
> For years my study group used smooth Balance Weights instead off smooth
> Down Weights when weighing off and we noticed that it made the pianos feel
> more dynamically uniform.  Using the BW method eliminates friction errors
> in the lead pattern.  This is the  major drawback to the Down Weight
system
> without a friction check.  
>
> When I started tipping keys onto digital scales and studying the results
we
> found that front weight patterns turned out to be smoother by using BW
> instead of Down weight but they were still irregular.  The Front Weight
> smoothness was made even smoother when hammer weights were adjusted prior
> to weight off by to make Strike Weight to a smooth curve.  I mean a major
> improvement.  
>
> We found that even when Strike Weights are smoothed and the keys balanced
> to a smooth Balance Weight, there are still significant note to note
> variations in the front weights.   These inconsistencies were eliminated
> with Equation Balancing using calculated Front Weight curves (US Pat
> 7877872).  This results in Front Weights that fit a smooth curve and
> pianists report that the pianos feel even better.  
>
> I'm aware that the Pattern itself is important.  Consider a case when two
> keys have the same front weight, one with one lead out to the front and
> another with say four leads in close to the balance rail.  The key with
one
> lead way out takes more force to accelerate to the same velocity as the
one
> with four leads in close to the rail.  At Reno I showed the pendulum rates
> of two balsa wood beams, both with the same front weight and lead pattern
> as above mentioned.  The pendulum rate of the beam with four leads was
> twice as fast as the beam with the single lead.  So it does make a
> difference how the leads are patterned in the keys.  
>
> John says:
>
> >I think it would be difficult to use key leads to balance the action
> statically and dynamically at the 
> >same time.
>
> The solution that we use with Precision TouchDesign installations is to
use
> smooth front weights and center symmetrical key lead patterns around a
> point half way in between the front of the key and the balance rail.  We
> keep the patterns as tightly spaced as possible. The patterns are always
> close to center line of the front half of the key.  We find that this
> addresses the dynamic quality sufficiently enough using practical static
> weight methods...  
>
> Here is a picture of a "Tower Pattern" as we call it:
>
> http://www.stanwoodpiano.com/Pa100088web.jpg
>
> I can hear some saying to themselves "that looks like a lot of lead".  The
> example given is a Kawaii with a 5.3 strike weight ratio and 1/4 high zone
> hammer weights with 44.5mm blow and 10mm dip.  The Front Weights are under
> my published "ceiling".  We know from experience that such setups play,
> feel, and sound great...
>
> Theoretically I can imagine that the most ideal and dynamically smooth
> displacement of weight added to the key for weighing off would be to use
> bars of metal, attached to the bottom of the keys, of varied lengths as
> needed to balance the key with their center point on the center point of
> the key but what's the point of hair splitting?  It's a good and necessary
> mental exercise that's what... but impractical and unnecessary in the real
> world.
>
> Thanks for the formula's John.
>
> David Stanwood
>
>
> P.S.- David... I don't understand the part of your question: "Why do we
> assume that even balance weight should be the standard which translates to
> a lighter feel at the upper end of the piano than at the lower end?"   
>
>
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