Aftertouch evaluation

[Keith Roberts]

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I agree with Richard in that it is a matter of feel. The jack must =
travel enough to escape the knuckle and have a feel of completeness to =
the stroke with no excess motion.=20
0.50 to 0.60 from the point of letoff is about right. Set a sample note =
and check to see that the jack is ending up where it is supposed to. The =
problem is to make all the notes the same. Blow distance changes =
aftertouch so make sure the blow distance is set on every string. Then I =
take a piece of hard plastic, 0.50 thick, the size of a keytop head, =
with a slot the width of a key pin notched in one end and slide that =
under the felt punching. What ever you use, a penny maybe, it has to be =
thin enough to have let off occur, then from your sample note, determine =
how far past let off the key is now traveling and adjust the key dip to =
match the sample. A piano with 0.60 aftertouch, the hammer will drop and =
rise ever so slightly as the punchings firm up. No rise, remove some =
punchings, etc.=20
The same plastic, in the shape of a keytop tail, slides in-between the =
white key pins to do the sharps in the same manner. This is a method =
that produces a very even aftertouch, sharps included.
Note to Bob Davis. Thanks for this method. It was a piece to the jigsaw =
puzzle that sat there for awhile before it fit into the picture. Knowing =
that you consider some of the methods you have developed to be =
proprietary, I apologize if I crossed that boundary, but hey, these guys =
need all the help they can get. <GRIN> I gave enough hints, they might =
be able to figure out what keytop material is already .050.  As you so =
eloquently posted, sharing information and techniques improves the =
overall quality of piano work around the world and comes back to us in =
form of respect for our profession and earning power. I must compliment =
you on your class at the CA convention, well put together and "the most =
applause at the end of the class" award.
Keith Roberts

----- Original Message -----=20
  From: Bob Hull=20
  To: pianotech@ptg.org=20
  Sent: Friday, March 14, 2003 10:49 PM
  Subject: Aftertouch evaluation


  I am wondering about the value of different methods of evaluating =
aftertouch on a grand. I know one method is to add punchings on top of =
those on the front rail pin until let-off can't take place;=20

  Another method I've heard of and used is to look at the final position =
of the jack in relationship to the knuckle and jack cushion after drop - =
but this can't be done with the action in the piano;  The next method =
(which I don't think I've read about anywhere) is my question to the =
list:  Can you accurately evaluate aftertouch by traveling the =
key/hammer through drop and then moving the jack tender downward to see =
how far the jack travels before being stopped by the jack cushion?

  Also, if you are using the addition of punchings on the front rail pin =
until let-off fails, what are some good parameters to stay within for =
"good" aftertouch, i.e. .050 - .060 ?  I know the Steinway manual says =
that a good amount is about the thickness of a new penny.  How far can =
we stray from that measurement and still be alright?

  Bob





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