[pianotech] Action Ratios Recap

[David Love]

Strictly required, necessary according to protocol, what it is.  Literally
from the French, of strictness.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of erwinspiano at aol.com
Sent: Thursday, January 14, 2010 7:45 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Action Ratios Recap

 

Definition---de regueur--required by current fashion or custom. New one to
me

  Dale

 

-----Original Message-----
From: David Love <davidlovepianos at comcast.net>
To: pianotech at ptg.org
Sent: Thu, Jan 14, 2010 7:33 pm
Subject: Re: [pianotech] Action Ratios Recap

My practical question may have been unclear to you but when I put this
question (If you are constructing an action and want one that regulates with
10 mm total dip and 46 mm blow where should you target the action ratio?) to
the individual who manufactures replacement keysets for me he was able to
give me a fairly precise answer with some slight variations depending on the
particular action model.
  Your description of after touch below is, of
course, de rigueur.  
 
David Love
www.davidlovepianos.com <http://www.davidlovepianos.com/> 
 
 
-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org
<mailto:pianotech-bounces at ptg.org?> ] On Behalf
Of John Delacour
Sent: Thursday, January 14, 2010 6:13 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Action Ratios Recap
 
At 16:08 -0800 14/1/10, Jason Kanter wrote:
 
>John, the same day of your detailed and interesting message, David 
>Love asked you:
> 
>OK.  So then from a practical standpoint, when converting action ratios as
>calculated by a product of levers to the relationship between dip and the
>requisite hammer rise to achieve a targeted blow distance with adequate
>aftertouch, what would you use?
 
Well the reason I didn't answer this is because it made little sense 
to me no matter which way I turned it.  There is one way and one way 
only to perform these calculations accurately and that is to use 
trigonometry.  What a "product of levers" means is not clear, but 
there is no way (and no point) to convert something based on a 
falsehood into a correct result.
 
As to the after-touch, the key must go down far enough after 
escapement commences to allow the roller (knuckle) to clear the face 
of the jack as the hammer falls into check, as is common knowledge. 
At that point the back of the jack is touching but not compressing 
the cushion.  Any further after-touch is unnecessary and detrimental. 
The tail of the jack rolls and slides on the set-off button -- as 
with the roller/jack contact there is inavoidable friction, but the 
exact distance the key must travel to accomplish this optimal 
escapement can be accurately calculated trigonometrically just like 
all the other relationships.
 
 
>and I asked you:
> 
>John, could you please add a definition of PROFILE?
 
Though the answer was included in the message that asked the 
question, I have made it clear in a separate message.
 
JD
 
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