[CAUT] Action saturation

[Laurence Libin]

If the action rail flexes, can this movement be felt by the player's hands, or only sensed aurally?
Laurence

  ----- Original Message ----- 
  From: Ed Sutton 
  To: caut at ptg.org 
  Sent: Wednesday, July 28, 2010 10:26 AM
  Subject: Re: [CAUT] Action saturation


  Incidentally, if there is a problem with the Steinway action rail flexing, it will probably be more obvious (weaker sound) in the middle of the rail section, with the least flexing at the section ends (stronger sound).
  es
    ----- Original Message ----- 
    From: A440A at aol.com 
    To: caut at ptg.org 
    Sent: Wednesday, July 28, 2010 8:53 AM
    Subject: [CAUT] Action saturation


    Ed Sutton writes: 


      Action saturation.
      As the pianist plays harder, the action parts flex more, so that eventually
      the force delivered to the string is determined by the whipping movement of
      the parts rather than the speed of the stroke to the key. The acceleration
      of the hammer has reached its peak. The pianist plays harder, but the only
      sound that gets louder is the thump to the keybed. 


    There is a great example of this in the "Five Lectures" series.  By comparing timing of the action components during varied levels of force, it becomes apparent that at some point, the key is hitting the punching well beore the hammer has finished its acceleration.  Taken to an extreme, it is possible to bottom the key out before the hammer moves much at all. Which means that the force hitting the string is limited to whatever compliance is found in the action.  I think the key is responsible for most of this, though the hammershank would run it a close second. The balance rail punching, capstan felt, and knuckle compression would come in third, with the small amount by rail flex and pin bushings contributing a little more.  
    Regards,. 
    Ed Foote RPT
    http://www.uk-piano.org/edfoote/index.html
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