[pianotech] Action Ratios Recap

[Mike Spalding]

Bravo!

Nick Gravagne wrote:
> Dear JD,
>
> First let me say that I have read and benefitted from many of your fine
> posts as well as the technical articles found at your web site
> http://pianomaker.co.uk/technical/. You are clearly an intelligent and
> most dedicated practitioner. We have all learned something from you, and
> hope to continue to do so.
>
> Now I have noticed that you don't mince words:
>
> A recent sampling from your pen:
>
> "... Pfeiffer's approximations as the scribblings of an amateur."
>
> "... woolly approximations..."
>
> "... Pfeiffer's laborious pseudo-proof..."
>
> And my favorite:
>
> "The class handout... misleadingly entitled 'Action Geometry: Truth and
> Consequences', has no truth in it at all and the consequence will be
> that any reliance on it will lead to wrong results."
>
> Your ironic use of the words "truth" and "consequences" conveys an
> almost Shakespearean ambiance.
>
> To wit: "Methinks, Horatio, when truth be false, the consequence worse!
> Whence ratio, Horatio, to me 'tis but lever; to others still I am found
> but too clever."
>
> Perhaps the reason that "nobody has even commented on" your Jan 10th
> post is because, as I see it, it is not complete, except for the
> rationale and mathematics of capstan rise to that of key dip. This,
> then, is followed by a broad and generalized argument in favor of
> trigonometry as the only path to success; not to mention a mind-numbing
> use of numbers carried out to eleven decimal places. 
>
> Your palpable criticism of Pfeiffer's work and, presumably, any modern
> technician's work who borrows from him has, I am guessing, not gone
> unnoticed.
>
> You are entitled, don't get me wrong. I have not ignored your post, but
> there is much to consider. Your argument that the most exacting ratio of
> key dip to hammer rise, as these relate to x and y positions of
> components gliding along arcs, is, of course, completely valid. What
> remains to be seen is what we gain from such exactitude.
>
> I have long thought that we yet lack a consistent and unified approach
> to the subject. I recently evaluated a Young Chang action by physically
> measuring the lever arms using three different methods, resulting in
> three different ARs of 5.9, 5.7 and 4.6. The AR that mostly agrees to
> the actual measurement (a bit tricky to do) of dip and subsequent hammer
> rise is the 5.7 AR.  
>
> The Levers and Ratios approach as used by much of the technical
> community, and as has been covered by me and many others on this list,
> has been roundly rejected by you. I am intrigued that you do so. I know
> that well-known names, whether pianos or technicians, do not impress you
> as your only motive is to get to "the truth" and let all trumpet blasts
> be damned.
>
> Very well, then, let's get to the truth.
>
> I will follow up soon with some ideas on how we might handle this issue
> with a degree of organization, clarity, consistency and professionalism.
> Handled as such, we all might learn something.
>
> BTW, the subject heading "Action Ratios ..." may have run its course.
>
> Respectfully,
>
>
> Nick Gravagne, RPT
> Piano Technicians Guild
> Member Society Manufacturing Engineers
> Voice Mail 928-476-4143
>  
>
>
>
>