[pianotech] Magic Line?

[reggaepass at aol.com]

Yes, in as much as having the capstan/heel intersection cross this line at half key travel minimizes friction.  The further off the magic line, the greater the sliding friction.



Alan Eder



Or, that that magic line point of intersection is a point of most efficiency?



-----Original Message-----
From: John Formsma <formsma at gmail.com>
To: pianotech at ptg.org
Sent: Mon, 16 Mar 2009 5:51 am
Subject: Re: [pianotech] Magic Line?







Yeah, I knew what it is.  Just wondered why it's called the "magic line."




Does it have to do with where the arcs intersect?  Or, that that magic line point of intersection is a point of most efficiency?




--

JF




On Mon, Mar 16, 2009 at 12:53 AM,  <PAULREVENKOJONES at aol.com> wrote:









John:


 


Since you don't know this, obviously you are not on the "need-to-know" 
list, and if we told you, we'd have to kill you. And here in Chicago, Guido 
does good business. 


 


Actually, it's quite simple. The one being talked about mostly is the line 
(which can be created in reality with string or thread, and can be seen in an 
action model with a straight edge) from the balance rail hole center at the key 
bottom extending to the whippen center. Ideally, the line would be intersected 
by the capstan top/whippen heel at half of the key travel. The capstan top 
and whippen heel rotate in opposite directions "bearing" on each other in 
different ratios in the counterbearing
 arcs (involutes) of travel. The leverages 
of the whippen and key change throughout that travel. 


 


That's it. No magic at all. Now, which knee-cap do you like the best? 
:-)


 


Paul






 




In a message dated 3/15/2009 11:01:31 P.M. Central Daylight Time, 
formsma at gmail.com writes:


I'm 
  going on the notion that the only dumb questions are the ones that aren't 
  asked. Go easy on me, OK? <G> 
  



  
Why is the "magic line" called the "magic line"?

  

-- 
JF












 




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