[pianotech] Action ratio measuring

[Ed Foote]

   "All actions are subject the accelerating action phenomena to 
changing
ratios thru the complete range of motion as the capstans is moving
further from the wip center pin and the increasing leverage efficiency
in the wip."


Greetings,
  From my perspecitve, If the geometry is such that the capstan's point
of contact is in line with the centers of both whippen and hammerflange
at half stroke, the capstan is moving closer to the whippen center pin
for the first half of its travel, and farther away during the latter
half. Hence, the ratio is increasing for the first half, and decreasing
for the second,which is against all that I understand about mechanical
efficiency. (shortest distance between two points is that straight 
"magic" line.)
    I like actions whose capstan contact point reaches the "magic line"
just at let-off so that the highest ratio occurs at the very last part
of the stroke where velocity is at its greatest, and the lowest ratio
at the beginning when there is so much mass to put into motion that a
lower gear makes sense.
Regards, .

Ed Foote RPT
http://www.piano-tuners.org/edfoote/well_tempered_piano.html