[CAUT] Key ratio measurement (was Re: moving capstans question)

[Fred Sturm]

On 9/23/07 3:43 AM, "Richard Brekne" <ricb at pianostemmer.no> wrote:

> I believe on 
> Overs site he mentions something about the need to take into
> compensation the angles at which the parts are designed to be in their
> rest positions to get the correct reading... because it will be
> different if you measure same in another position.

    It occurs to me that the "elephant in the room" is the degree to which
in non-Overs action pianos the knuckle is away from convergence (way below).
Maybe that is the answer to my question right there (along with possible
wipp/capstan non-convergence).
    I did find it rather distressing to try out all four (including
Spurlock's addition of weight to hammer) methods and come up with a
different number for each, and not just a little different, either. I was
thinking of coming up with a kind of quickie way of predicting an optimum
blow/dip relationship and ball park numbers. Maybe practical, or maybe not
(probably the old experimental "try this, try that" method is just as fast
in the long run), but it seemed like it would be cool if it worked. No
wonder manufacturers' specs are just starting points a lot of the time <G>.
Unless they have really fine manufacturing tolerances, like our Japanese
friends, and probably many of the Germans as well.
    But it does make me wonder if a lot of talk about ratio numbers is at
cross purposes, because different people are measuring different ways.
Regards,
Fred Sturm
University of New Mexico