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

[Fred Sturm]

Hi Barbara,
    I think the best way to learn this stuff is by fooling around while
regulating. I am a great believer in adjusting drop without a gauge (taut
line or solid), using letoff as the reference. I think probably most
instructors teach this method at this point.
    You have set letoff in the action cavity, in reference to each string.
(I like to use Spurlock¹s jig for an initial, efficient, and quite precise
³rough pass,¹ then touch up in the cavity). With the action on the bench,
you then press on each key in turn and come to that contact point, where the
rep lever and/or jack tender is contacting the drop screw and/or regulating
button, and from that point slowly, in a very controlled way, go just barely
through letoff. And stop the key motion right there. How far did the hammer
drop from its highest point? I like to hold the neighboring hammer in drop
position (meaning hold down the neighbor key) as a reference point, a stable
point from which to reference that highest point and the drop point.
    Now there is a feel in the key as you hit the contact point. There is a
distance of key travel starting with the hammer at rest, and then you hit
spring resistance. If drop is set quite far ­ say 8 mm from letoff (and this
isn¹t that uncommon to find in the field) - there will be a ³spongy² contact
point, one that isn¹t entirely firm. From key at rest to the contact point,
using a sensitive touch, you can use slightly different pressures or
³controlled keystrokes² to what you feel as the point of contact (where the
free movement suddenly meets more resistance) and you will end up at a
different point depending how much pressure or speed you were applying. Kind
of like how a hammer line behaves when you have your rep lever set to high
relative to the jack top. And you can gauge this by how high the hammer is
as you hit resistance ­ it will vary. You can train your fingers to feel the
difference between this and having the contact point include the jack tender
on the button. When the jack tender is hit, the spring resistance also
becomes the scraping of the jack top on the knuckle, which is different from
just spring.
    So this is one variable in feel. Another is the feel from the beginning
of contact (whether ³spongy² or not) through letoff to the drop point. One
factor is the distance of key travel involved, which will be mirrored in how
high the hammer goes from the moment you feel the resistance. Another is the
actual scraping of the jack top on the knuckle. And a third is the feel of
the drop itself, as a thump causing a ³bounce back² at the key. If you have
a deep drop, you will have a long key travel, ending in a pronounced thump,
with an extended jack scraping against knuckle due to it catching more of
the side of the knuckle during letoff (scraping on the side toward you). A
very pronounced ³positive feel.² As you decrease drop to about 2 mm below
letoff point, that key travel decreases, as does the thump and the degree of
scrape. Also, the height of the hammer at the contact point will be higher,
and the distance it travels upward from there to letoff will be less. If you
reduce drop more, to 1 mm and even to the point where there is just zero
drop, the feel of letoff becomes more and more imperceptible, less and less
positive. There is just spring resistance and a slight brushing feel.
    Now let¹s step back and set drop at about 1.5 mm below letoff (assuming
letoff was set around 1.5 to 2 mm). Feel that bit of key travel between
contact and drop point. Now adjust the jack alignment back 1 mm, and feel
again. Now adjust it 1 mm forward of where you originally had it and feel
again. Feel what those differences are. Essentially you have more scrape of
jack on knuckle with the jack back, less with it forward, though there is
also a subtle spring effect. Hone in and do differences of 0.5 mm forward
and back.
    I think that practice like this, building up the sensitivity of the
fingers, is very important to do if you want to satisfy artistic customers.
I¹ve left out aftertouch, which is intimately involved with the ³feels² I
have described, but maybe it is fairly self-explanatory: fool with the
capstan on an individual key, action in the cavity, to feel a range from
zero aftertouch through ³a lot.² As ³a lot² is decreased toward zero, the
positive feel reduces. But the ³amplitude² of positive feel (resistance
during the movement from contact through drop) was set in the
drop/letoff/jack alignment phase.
Regards,
Fred Sturm
University of New Mexico


On 8/10/07 9:17 PM, "Barbara Richmond" <piano57 at insightbb.com> wrote:
> Hi Fred,
>  
> Thanks for the explanation.  I'll take you word for it, but I'll still have to
> give it a try to prove it to myself.  ;-)
>  
> This thread came up at an interesting time for me, since I've been working on
> a S&S B that the owner complained of what you would describe as "positive"
> feeling--or too much of it.  So speaking in terms of positive or not, is
> really helpful.  This is the first time I've had a pianist complain of such.
> When I went to pick up the action to rebush keys and make various repairs, the
> pianist complained of heaviness in the action. I asked her to show me the
> notes that were the worst, and to me, they were the notes that were regulated
> the best.  Well, that was a strange feeling...
>  
> BTW, I adjust jacks seated (or standing) by the ends of the action.  I didn't
> know there was any other way!  In the bass, pressing down on the rep lever
> with my left hand to see where the jack is, making the adjustment with my
> right.  After making the adjustment I release and have a second look to make
> sure everything is where it should be.  As I work, I flip up the hammers to
> get them out of the way.    It's easy to glance through the action to see the
> tool going in for the correct screw.  After getting half way, I work from the
> treble end--yeah, my left hand has to use the tool, but I can do it.  Using an
> action caddy (I love that thing!) makes this operation especially easy,
> minimizing the amount of time I have to stand and lean over the action.  It
> goes pretty fast.
>  
> Thanks much!
>  
> Barbara Richmond, RPT
> near Peoria, Illinois
>> ----- Original Message -----
>> From: Fred Sturm <mailto:fssturm at unm.edu>
>> To: caut <mailto:caut at ptg.org>
>> Sent: Friday, August 10, 2007 6:55 PM
>> Subject: Re: [CAUT] Black on Black... (Jack alignment)
>> 
>> On 8/9/07 4:07 PM, "Barbara Richmond" <piano57 at insightbb.com> wrote:
>> 
>>> Well, this thread took an interesting turn while I was away from home.
>>> 
>>> Fred, tell me about moving those jacks on a well-regulated/lubed piano.  Is
>>> that "all" you did?  I mean, you couldn't just move 'em back and be done.
>>> I've never tried it--you had to go through everything again (right?).  I
>>> would be interested in knowing what changes to aftertouch you might have had
>>> to make as a result of it.  Of course, I could go experiment on my
>>> piano...but it's easier to ask.  :)
>>> 
>>> Thanks,
>>> 
>>> Barbara Richmond, RPT
>> 
>> Hi Barbara,
>>     Actually, advancing jack alignment doesn’t affect aftertouch. It does
>> affect simultaneity of drop/jack tender contact a bit. Why doesn’t it affect
>> aftertouch? Well, though the tender will contact the regulating button
>> earlier, it will still get the jack to the point of letoff at exactly the
>> same point in key travel, and exactly the same relative to the string. So you
>> can actually nudge it (the jack line) back or forward a bit without doing
>> anything else if you want to, and not be caught by the regulation police.
>>     Moving all the jacks less than or maybe up to 1 mm will have a very minor
>> affect on that letoff/jack simultaneous touch, but I don’t think it is enough
>> to really feel in isolation. You can fool with all three - letoff, drop and
>> alignment – to come up with an effect, of more or less obvious feel of the
>> letoff part of key travel. Less drop and alignment forward makes for less
>> obvious feel. So does increasing letoff a tad and leaving the others the
>> same. Increasing drop and/or decreasing letoff means more positive feel, but
>> with decreasing letoff you decrease aftertouch, which partly negates the
>> positive feel thing (more aftertouch also means a more “positive feel).
>>     It’s kind of a balancing act, but when you are in a pretty sweet spot,
>> you can make minor adjustments without really redoing everything. Does that
>> answer your question, or just make it more confusing?
>> Regards,
>> Fred Sturm
>> University of New Mexico
>> 
> 


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