[pianotech] FW: [PTG Pianotech]: Key Leads

Dale Erwin erwinspiano at aol.com
Sun Nov 11 20:34:30 MST 2012


I agree with David here. Leading is the symptom not the problem.The geometry of the system is simply being overloaded with too much hammer weight. 
 I've done many of these early 70s Bs actions & I find it necessary to move both the knuckle and the capstan to achieve a ratio near something more workable such as 5.5 to 1 or thereabouts. Then popping out keyleads is both necessary and beneficial to a more workable inertia/balance weight.
Dale


Dale Erwin R.P.T.
Erwin's Piano Restoration Inc.
 Mason & Hamlin/Steinway/U.S. pianos
www.Erwinspiano.com
Phone: 209-577-8397

 
  





-----Original Message-----
From: David Love <davidlovepianos at comcast.net>
To: pianotech <pianotech at ptg.org>
Sent: Sun, Nov 11, 2012 5:56 pm
Subject: [pianotech] FW: [PTG Pianotech]: Key Leads


The issue of too many leads is really misdirected.  The *reason* that there are 
too many leads is more the issue.  That happens because the action ratio is not 
a good match for the hammer weights (or strike weights if you prefer).  The 
inertia in the system derives from the relationship between action ratio and 
hammer weight more than from key leading no matter where you put them.  The 
excess key leads are a symptom.  Removing leads will not lower the inertia 
significantly and will only increase the balance weight.  If the piano has too 
many leads and doesn't balance at a reasonable balance weight then the 
ratio/hammer weight relationship is off and you need to fix that first.  
Steinways from the 1970's tend to have high(er) ratios *and* high hammer 
weights.  Bad combination.  Convert the 16 mm knuckles to 17 mm knuckles is 
generally the first order of business.  A methodology that allows you to analyze 
the action ratio and combine it with the proper hammer weights is better and 
will result in the key leads being more conforming.  Even the notion that moving 
leads toward the balance rail is somewhat misguided.  While it does reduce the 
inertia that is contributed by the leading pattern in the keys, as far as the 
overall inertia in the system, it's not that consequential.  

David Love
www.davidlovepianos.com


-----Original Message-----
From: Paul Williams [mailto:noreply at egroups.ptg.org] 
Sent: Sunday, November 11, 2012 2:24 PM
To: David Love
Subject: [PTG Pianotech]: Key Leads


This message has been cross posted to the following Discussions: CAUT and  
Pianotech .
-------------------------------------------
Wow! What a lot of key leads on the cover of the Journal!

 Question: when you you all remove lead?  It's a nasty thing.  I know that  more 
than 5 is bad in bass.and none is optimal in the treble.  Where do you  draw the 
line on '70's Steinways?? some of mine are out of control with too  many leads. 
they play pretty well. but what should I do in the long run?

 Best,

 Paul


 -------------------------------------------
 Paul T. Williams RPT
 Piano Technician
 University of Nebraska
 Lincoln, NE 68588-0100
 pwilliams4 at unl.edu
 -------------------------------------------

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