Bechstein grand spread dimension,

[David Love]

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Stephane:

Thanks for catching that, yes I meant increase the blow distance to =
reduce aftertouch. =20

Good aftertouch has to do with jack clearance from the knuckle when the =
key is fully depressed.  More than 1.5 mm is unnecessary.

I don't like to alter the angle of the jack relative to the knuckle, but =
I see it happening on vintage NY Steinways that go to 17mm knuckles.  =
Though in that case the knuckle will incline toward the hammer more, =
whereas by increasing the spread, the jack will incline toward the =
hammer flange more.  I suppose in making the choice between spread and =
blow it would depend on how much deviation is necessary.  I don't like =
to lengthen the blow excessively.  It adds weight to the action and =
creates a feeling of lack of control.  Also, if the action ratio is so =
high that you are significantly compromising regulation, then it might =
be worth assessing the weight and balance as well.  Higher action ratio =
not only means shorter dip, or longer blow, but, more importantly, =
poorer force leverage.  In short, anything you do will be a compromise, =
so you just have to try some samples and see how it works.   If you =
can't get it to regulate the way you want, further analysis of the =
placement of the capstan/knuckle might be in order.

David Love
  ----- Original Message -----=20
  From: St=E9phane Collin=20
  To: Pianotech=20
  Sent: September 16, 2002 3:06 AM
  Subject: Re: Bechstein grand spread dimension,


  David,

  Just two questions.

    Action ratio is equal to=20

    blow distance - letoff=20
    key dip - after touch=20


    By increasing the spread you will lower the action ratio.  A lower =
action ratio will mean that the piano will require deeper dip.  Or, in =
your case, you will have less aftertouch.   Before doing this, you will =
have to make sure that altering the spread doesn't create other problems =
especially in terms of jack/knuckle alignment. =20

    The other alternative is to reduce the blow distance. =20

  If I follow you, didn't you mean increase the blow distance (in order =
to reduce the aftertouch for the same key dip and same action ratio) ?

  Can I ask you how you define a good aftertouch ? By feel at the key ? =
by precise measuring (at the key or at the jack) ?=20

  And indeed, do you feel it is more important to keep good alignment =
between jack and knucle core, and therefor altering preferrably the =
hammer blow ?

  Thanks for your expert advises.

  St=E9phane Collin.

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