[pianotech] Action Ratios

[David Love]

Except that the left side is taken as an average (half blow) and according
to those that use the equation does balance or equate.  I'm just wondering
if there is a formula in which you can plug in the desired dip and blow (as
this one purports to do) and come up with an action ratio needed to produce
those specs.  Though this one attempts to do that I don't see it working
except somewhat artificially.  

David Love
www.davidlovepianos.com

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of jiimialeggio
Sent: Wednesday, January 06, 2010 5:58 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] Action Ratios



David Love wrote:
>
> Thanks for that clarification and explanations, however, even with 
> that the numbers don't make sense. Let's assume that the left side of 
> the equation produces an action ratio of 5.5-a fairly standard target. 
> Then if we look at the right side of the equation and target a key dip 
> of 10mm, say. By your analysis the denominator would be 7.5 (.75 x 10) 
> making the numerator 39.7mm representing blow distance minus 
> let-off??? That doesn't seem to bear any resemblance to what one would 
> expect from an action ratio of 5.5 in practice. Clearly the 
> dip-aftertouch number is at issue but the assignment of the AT number 
> seems somewhat arbitrary in order to make the formula work. What, 
> then, is the point of the right side of the equation at all?
>

Unless I'm completely missing something, the reason the right side of 
the equation can't make proper sense with the left is that the action 
actually has a variable ratio. 5.0 is @ half but considerable higher at 
the beginning of the stroke, fallingand 0 at letoff. As I see that 
equation, it is assuming the ration @ 1/2 stroke is constant throughout 
the entire kestroke=not true. Action rations seem to me to be confusing 
designations, since you really are talking either about an average (I 
don't see that factored into the left side), or a fictitious static 
number. No?

Jim I
grandpianosolutions.com