Grand Jacks

[Tom Driscoll]

Rep lever height and spring strength(or lack of) , jack to knuckle orientation, knuckle condition, jack and rep lever surfaces , tight action centers ,and maybe a few more reasons.
    READ----- REGULATION !    
Check your Randy Potter literature.I bet he has a whole chapter or more on grand action prep and adjustment.
Tom Driscoll RPT
  ----- Original Message ----- 
  From: Matthew Todd 
  To: pianotech at ptg.org 
  Sent: Sunday, August 17, 2008 6:40 PM
  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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