[pianotech] Upright Key Weighting

[John Ashcraft]

Floyd,
I agree with Joe. Adjusting the springs will give you a static downweight
in the right range, and the piano will play well at pianissimo. This is a
good last step.

The mass of the hammers comes into play much more at fortissimo, where the
perceived force is increased, since F = ma. The faster acceleration of the
key/hammer system is felt in the fingers of the player. If you have
low-mass hammers, you feel like you are falling into the piano. A 10-gram
hammer at middle C will feel like 50 when you look at the 1:5 mechanical
disadvantage with 3/8" key dip and a 1-7/8" hammer travel. A 9-gram hammer
will feel like 45. The hammer mass gives you a dynamic downweight feel.

So, if you want the piano to feel more like a 52-gram-downweight grand,
look at the hammer mass.

John Ashcraft, RPT
Portland, OR Chapter

On Wed, Jan 18, 2012 at 4:35 AM, Floyd Gadd <fg at floydgadd.com> wrote:

> **
> List,
>
> I have a client (a piano teacher) with a 1906 Heintzman upright piano.
> She is concerned that the touch feels too light--that there is too big a
> distance between what her students encounter on this piano and what they
> will find when they play in festival or in an exam.
>
> First, an assumption.  Let's assume that the "preferred" pianos against
> which this is being compared are not just badly weighted and regulated
> grands; let's assume the the comparison is against a well set-up grand.
>
> The Heintzmans of this era tend to be well designed and set up.  This
> piano behaves pretty much like any of its contemporaries in  good playing
> condition.  Friction  and wear are not significant contributors to the
> complaint.
>
> My experience in altering the key weighting of verticals has been focused
> on small pianos from the 1960's.  Following a post in this forum by Stephen
> Schnell (November 18th, 1996) in a thread called "Small vertical key flop",
> I have been backweighting keys for an upweight (with hammer held out of the
> way) of 15 grams, then adjusting the hammer return spring to achieve a
> downweight of 50 grams, or thereabouts.  Add to this the normalization of
> friction throughout and thorough regulation (especially damper timing) and
> I end up with a much improved piano.  But here the initial problems being
> addressed tend to be excess effort (against the hammer return spring) to
> depress the key, and poor key return.
>
> The Heintzman I am working on has good key return.  Downweight is somewhat
> below 50 grams, and I do not recall what the upweight is, but I seem to
> remember it being less than 15 grams.  There are, if my recollection is
> correct, no lead weights in the keys.
>
> My inclination is to pursue the same course of action I have used with the
> smaller verticals--achieving a target upweight with springs out of the
> picture, then regulating the springs to achieve a final result.  I think I
> should be aiming for a final downweight somewhere in the order of 50 grams.
>
> Any suggestions or guidance on this?
>
> Floyd Gadd
> Manitoba Chapter
>
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