[CAUT] Black on Black... (Jack alignment)

[Leslie Bartlett]

The wealthiest technician in houston is blind. he has done a couple programs
on "tricks the blind use" and he always sets jacks by feel.  I have fixed a
fair number of them by feel only, and have seemed to have success.
les bartlett

  _____  

From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Fred
Sturm
Sent: Tuesday, August 07, 2007 7:14 PM
To: caut
Subject: Re: [CAUT] Black on Black... (Jack alignment)


On 8/6/07 3:50 PM, "Jim Busby" <jim_busby at byu.edu> wrote:



Hi Jon, 

You know, my gut feeling tells me that this (white out) will work and solve
my immediate problem. However, have you tried the "feel" method Michael W.
wrote about? I've used that method to check for cheating jacks, but have
never set jack position with it. I'm wondering if this "feel" of the jack
will be as accurate (or more) for touch as the sight method. Once again,
asking a simple question like this has caused me to examine my own long-used
techniques. His experience is more vast than mine so. I'm off to experiment!


Regards,
Jim Busby



    Yes, the standard of "line it up with the knuckle core" is more
tradition than absolute, though it is a great place to start. Lining each up
visually is a near impossible job, at least to achieve real precision. Your
eye has to be very sharp, and placed precisely right and consistently so for
each and every note. That little bit of offset means that even a slight
change in angle will affect what you see, and you are having to extrapolate
a line past a gap. The jack is set in under the knuckle, and the core
doesn't extend all the way to the leather. Quite a big gap to bridge with
the eye. And if you are adjusting each jack to the neighboring core, you
aren't doing a custom adjustment.
    I have found that I get better results by setting ends of sections, and
then using a straightedge to regulate between the ends. I make use of the
scoring lines if they are present as references. Also use those polished
segments on the rep tops, in well used actions. This method provides a very
good starting point.
    I am skeptical about actually regulating by adjusting the jack so that
it will cheat, then adjusting it back in so it won't. Why? A couple reasons.
First, it is hard to be sure you are being consistent. Same number of turns
(number of degrees of turn) may not give a consistent distance because the
regulating button may not always be square to the screw. And the "point of
cheating" may not be consistent, due to leather irregularities or to
technique on the key (while testing for cheating). 
    I am also not sure that we want to regulate so that there is the least
possible scrape of the jack on the knuckle during escapement, consistent
with a position that doesn't cheat. I think there is quite a bit of effect
on the feel of the action here, and that one usually will want a little bit
more than the bare minimum, to give a more "positive feel" to the pianist.
At least, some of my customers (and my own taste) have led me to think this.
    I do like Michael Wathen's method if it's used for finding cheating
jacks. Very convenient not to have to hold your finger or hand on each
hammer. And I'll suggest that a rapid flick motion rather than a hard press
is best to find those borderline cases. Fast as you can, but not necessarily
much force, will find them best.
    Me, I like to fine adjust jack position while I am doing my last pass on
drop. At that point, I am pressing each key very slowly and controlled,
feeling as the key goes from that point of - darn, the word escapes me.
Convergence comes to mind, but I don't think that's right. Starts with con,
though, I think. It's the point when drop and letoff touch simultaneously.
So feeling from that point and watching the hammer go to its highest point,
then drop that little, very consistent bit. There is a feel to this that I
am looking for, that has some resistance and bump to it, but not too much.
If one note feels right and the next one has less bump/resistance, but drop
is identical, I want to adjust the jack a bit inward under the knuckle to
get the same feel. And vice versa, if there is more bump/resistance. 
    I think that this is the real fine point of regulation, together with
utterly consistent aftertouch. This is where you make a piano feel
wonderful. (Of course, you have to have laid an excellent groundwork before,
in all the other regulation points). This is where our German colleagues
focus a lot of attention, and I think they are right to do so. Hold the
pedal down, lightly press a handful of keys (five) with your fingers to that
point whose name I can't remember, and then play each through to aftertouch
in turn. Very sensitively. This is where jack position comes into play,
along with consistent letoff and drop (and the relationship between them),
and aftertouch. Once you have the feel in your fingers, you can make little
adjustments to make that point more obvious, or make it almost disappear,
according to taste. There is a middle ground that I think most people will
like.
Regards,
Fred Sturm
University of New Mexico 




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