June Journal and FW's

[David Love]

----- Original Message -----
From: "Bill Ballard" <yardbird@pop.vermontel.net>
To: <pianotech@ptg.org>
Sent: May 30, 2002 9:04 PM
Subject: Re: June Journal and FW's
> Just as a fine tuning of BW? It seems a waste of their abilities.

Some older European pianos I have played have had assist springs with very
little leading in the keys.  Though those actions may not have been
precisely balanced, they certainly were low inertia.  I have not been overly
impressed with that set up.  But I can't say definitively.  It's not hard to
set up an action with relatively low inertia without assist springs.  I am
not yet convinced of the benefit there unless you want to go to heavier
hammers.  But I am still open minded.

But right now it seems that one either uses assist springs to adjust for
uneven SBR, or to allow for adjustable BW's, or both.  Assuming for a moment
that adjustable BW's are not that important, I'm not convinced that trading
even FW's for uneven WAS tension isn't just trading one type of unevenness
for another.  That being said, I can definitely see the value of equal SBR
through the entire action.  I have been experimenting with getting even
ratios by altering the spread from note to note (it doesn't take much) when
the SBR doesn't fall into place.  After setting up the action with smooth SW
curve and logging all front weights, I all measurements and on a spread
sheet calculate the SBR.  If the ratio is too high on a given note, I
increase the spread slightly by shimming out the wippen flange from the top
of the flange.  Vice versa if the ration needs to be increased.  Retest, in
put the numbers until the SBR is relatively uniform.  This is not unlike
setting up a staggered capstan line on a piano that has uneven KR on sharps
and naturals.  Here it can be done with the spread.  Steinways are very
friendly this way with the flange mounting they have.

Once this is done, the FW's will fall into place in a uniform pattern
assuming a smooth SW curve.

Real SBR uniformity seems better than artificial SBR uniformity created by
the use of an assist spring with varying degrees of tension.  For one, the
action will regulate uniformly from note to note.  You may be able to
compensate for FW's with an assist spring if you have one note at SBR 5.4
and another at SBR 5.8, but you won't cure the regulation irregularities as
well.  Assuming that pianos will always have manufacturing irregularities
that will cause uneven SBR's, this seems like a possible, though not
perfectly clean, solution.

So the other reason to use the assist spring is to have variable BW
settings.  I can see that this as a real advantage if you are unsure of the
pianists tastes, or if they are, and you don't want to have to drag the
action back to the shop to make minor changes, or if someone just wants the
latitude to change their mind.  But I don't see that a variability of 10 -15
grams is necessary.  I would guess that 99% of pianists would be satisfied
with a BW between 36 and 40 grams.  Throw in an extra gram on either side,
even out the SBR by the method I have suggested and preweigh the action at
41 BW with springs detached.  Minimal use of the spring would then allow you
to take the action down without experiencing some of the unpleasantness of
highly tensioned springs that I have experienced.

I wouldn't call that a waste of their abilities.  It may turn out that their
best use is to mitigate small deviations in a small way.  Why push their use
to the maximum where, by some consensus, problems can occur.

Of course, if you want monster hammers... well that's different.

David love