jack slides out before delivering power

David Skolnik davidskolnik@optonline.net
Tue, 23 Nov 2004 11:17:15 -0500


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Julia -

Your description of the symptoms remains a bit unclear.  Do you mean that 
if you were to sit down at the piano and play each note forcefully, once, 
that each would play, but if you were to do the same with a minimal force, 
it would not?  Or is it that a note, after being played softly once, will 
cheat when attempted again?   While Issac and David Stahl might be correct 
in assessing the jack pinning as the problem, it could also relate to key 
leveling, though the opposite to what you suggested.    If there is not 
enough (just enough) lost motion, the jack will not return under the butt 
on a slow (soft) release. Besides leveling, other possible contributing 
keyboard issues could be either excess friction or excess front 
weighting.  This could be further aggravated by tight wippin pinning, 
excess friction between jack top and butt leather, bad geometry of the butt 
profile,  incorrect thickness of butt cushion, or an imbalance between 
hammer return spring and jack spring.

I recall working on a small Steinway consol, some years ago, where the 
configuration of the lower butt geometry created the dilemma where, by the 
time I eliminated excess lost motion, the jack would not navigate over what 
appeared (to it) as an inverted speed bump.

On the other hand, it might just be the jack pinning.

Let us know.

David Skolnik



At 11:52 PM 11/22/2004 -0500, you wrote:
>Greetings,
>
>              Working on a Hamilton built by Baldwin studio upright today, 
> I noticed that  on a reallly soft blow to the key, the jack wants to slip 
> forward almost to the back of the catch's shank, instead of delivering 
> the kick to the base of the hammer butt.
>
>              The customer complained that, on a soft blow the key 
> wouldn't play and would sort of jam. Looking at this situation I saw that 
> the jack would sometimes just slip out too much forward and not deliver 
> its power. What would cause this? Could the keys not be levelled high enough?
>
>Julia Gottchall,
>Reading PA

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