[pianotech] boring, (was Hammer strike line)

[PAULREVENKOJONES at aol.com]

In a message dated 2/8/2010 9:57:52 P.M. Central Standard Time,  
erwinspiano at aol.com writes:

   Hi Ed
  What do you find the  average amount of over centering to be ie. no. of 
MM s the center of the  hammer shank rises above the center pin  height?

Mixing it up a bit, if you move the hammer toward the front by, say, 4mm,  
what is the over-center condition (measured the way you suggest, Dale)?
 
 

  Also I  am most curious as to your subjective opoinion about what  
discernable differences in sound..if any? 

This is the most telling question, I think, after determining whether there 
 is significant enough over-centering.
 
P
 
 

    uhhh...and the  shank is parallel to what zzzzactly?
  Thanks Pal
   Dale





-----Original  Message-----
From: Ed Foote <a440a at aol.com>
To:  pianotech at ptg.org
Sent: Mon, Feb 8, 2010 7:51 pm
Subject: Re:  [pianotech] boring, (was Hammer strike line)


Dale writes:  


Perhaps the  idea Ed was getting at was that whatever degree the string 
slope is  that there should be a corresponding  amount of over centering and  
rake so the string and hammer are at right angles to each other ant the  
keybed. However this means calculating the slope on each piano or just  checking 
it and averaging the bore. I think I just devised an A B  Expereiment. I'll 
work on it



I do calculate  the bore distance to the slope. I do this by using a set of 
graduated  "hammers" glued up to shanks and flanges.  Actually, the 
"hammers" are  various lengths of the Renner slats, glued to the shanks at exactly 
90  degrees.  By putting, say, a 49 mm "hammer" in the piano, I can simply  
lift it to the string, drop a square down along its edge, and instantly see 
if  it is at right angles to the string. When I find the correct length, I 
know  that upon contact, the hammer is at 90 degrees to the string, and the 
shank is  parallel.  It is quick, accurate, and easy.   
Regards,

Ed Foote  RPT
_http://www.uk-piano.org/edfoote/index.html_ 
(http://www.uk-piano.org/edfoote/index.html) 


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