on needling old upright hammers

[Dave Nereson]

----- Original Message ----- 
From: <Alpha88x@aol.com>
To: <pianotech@ptg.org>
Sent: Friday, July 16, 2004 1:36 PM
Subject: on needling old upright hammers


> Greetings,
>
>              We were told in piano tech school NOT to needle hammers right
on
> the crown. Upon arriving home from 9 months at tech school, I was
Jones-ing
> to refurbish my old upright and needle the hammers in my Yamaha U3, as the
tone
> was harsh on both pianos.
>
>               Well, I first did the old upright's hammers. Needled the
> "shoulders of the hammers careful to not go near the crowns. Put the
action back in
> the piano and I heard hardly no change. That horrible harsh, explosive,
glassy
> sound prevailed. So, I decided to slightly needle just a few of the
offenders
> alittle closer to the crown. No difference...tried alittle further into
the
> crowns....To make a long story short, I didn't alleviate the harsh tone
till I
> deeply pounded the needle right in the crowns of the things! What gives?
>
>                I got the results I wanted, namely a more mellow tone, but
> only when I did exactly what I was told NOT to do.
>
> Julia Gottchall,
> Reading, PA
>

    Yes, most instruction on voicing cautions against needling right on the
crown.  For good reason.  If you needle TOO MUCH (and that's the essential
phrase here) right on the crown, you may soften the tip of the hammer too
much and kill its power and resiliency.  But the reason most pianos with a
harsh, glassy tone sound that way is because the felt has become packed down
and hard in the string grooves.  If you space the hammer over so that it
hits in between grooves, the tone will be totally different.
    But that's not a practical solution.  If the grooves are quite deep
(more than the string thickness), file the hammers first.  Then see what the
tone is like.  It's probably even brighter than it was before, but at least
now, if you did a good job, the hammers are striking all three strings of
each unison simultaneously and if you have to align hammers to strings, they
will hit on a smooth even surface, rather than trying to "find" the old
string grooves.
    Now you can voice, and I believe a recent article in the Journal
encouraged voicing right on the strike point (crown).  As long as you don't
excessively jab deeply into the crown, you won't destroy the hammer.  Some
old pianos have very soft hammers already.  There, you'll probably want to
exercise some caution.
    But if the felt seems quite dense (it usually is on Asian pianos), you
can probably do a fair amount of needling on the crown before you damage the
hammer, as long as you're not stabbing too deep, and with dense felt, the
needles usually won't even go in that far.
    After reading that recent article about crown voicing, I think I may
agree that stabbing in radially with needles probably cuts some of the
fibers, and especially with Yamaha hammers, which tend to pull apart at the
crown because of their high tension, this may exacerbate the problem  (make
them tear apart at the crown).
    The author (I could go look it up, but it's out in the car) recommends
side voicing (pushing the needle in from the sides of the hammer).  You have
to support the hammer with your other hand so you don't break the shank or
bend the center pin, of course.  [Side note:  I wonder if the pliers-type
center pin extraction tool could be modified to a voicing needle instead of
a pin punch for this purpose.  Or does someone already offer a pliers-type
side-voicing tool?]
    There was another article a few years ago entitled "Voicing for the Rest
of Us", where the same thing was recommended.  He pushed the needle in from
the side, about an eighth of an inch below the surface and under the ends of
the string grooves.  In a low tenor hammer, that would be about an eighth of
an inch, maybe 3/16" above and below the strike point.  In the high treble,
maybe only 1/16" above and below the strike point.  (If the hammers have
been recently filed, and if the crown is more diamond-shaped (Yamaha) than
rounded (Steinway), then the string impressions won't be as long.)
    Some hammers may be too dense to shove needles in from the side.  I
guess then you just have to stab radially or use (judiciously) ViseGrips or
the hammer-squeezing type voicing pliers (a more sophisticated tool that
accomplishes the same thing as the ViseGrips but with a better designed
jaw).
    So, yes, be careful around the crown, but it's not so "sacred" as we're
sometimes led to believe.  The "shoulders" can be thought of as extending
all the way up to 11:58 and 12:02 (in my opinion, from what I gather, and
from what I experience on the pianos I've worked on).
    --David Nereson, RPT