Grand Jacks

[Porritt, David]

Repetition lever set too low.  What you did was the way to check the
repetition lever height.  Old timers call that "rolling the flies".  If
you trip the jack and you just barely feel the top of the jack scrape
the knuckle but it does return fully on its own, the rep height is
correct.  The tightness of the jack bushings is another matter.  They
should be pretty free.

 

dp

 

 

David M. Porritt, RPT

dporritt at smu.edu <mailto:dporritt at smu.edu> 

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf Of Matthew Todd
Sent: Sunday, August 17, 2008 5:41 PM
To: pianotech at ptg.org
Subject: Grand Jacks

 

I have been observing a grand action, and I was curious about something
(is that a surprise??)

 

A)  I went and tripped each jack toe and I noticed that some of them
when I tripped the jack toe down, and then released it, the toe
immediately went back up.  B)  On others, I tripped the jack toe, and
when I released it, the toe went up, but not fully, and I would gently
push the toe and would feel the "click" of the toe returning to it's
position.  C)  And yet, on a few others, when I pushed down the jack
toe, and then released it, the toe would stay down (assuming a tight
flange here).

 

What should be the consistency with each note?  I'm assuming, after I
trip the jack toe and release it, the jack should return fully to where
it began.  What other problems can there be besides tight flanges to
have the jack not return fully?

 

Thanks,

Matthew

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