[pianotech] high leverage action

[Gene Nelson]

Hello Ric,
Back with just a bit of data:
Moving the whippen heals as close to the whippen flange as possible (about 
3mm)
gave considerable more hammer travel for the 10.5mm key dip that I did not 
change.
Blow increased from 41 to 47mm. The expense was an increase in balance 
weight from around
40 to around 44.
I changed the action spread just to see what would happen, reducing it from 
113mm to 112 mm and
the effect was similar to the above. The bonus was that the knuckle jack 
alignment improved. Put back to 113 at end of day.
Now the capstan whippen heal interface puts the capstan at the extreme edge 
of the whippen heal - especially in the treble.
I had hoped to move the capstans closer to the balance rail by 3mm but not 
with these whippen heals in this new position.
Put everything back like it was and the 41mm blow distance returns. 
Basically this was nothing more than centering the whippen heals on
the capstans.
It is curious to me that the measured key ratio and the weighted KR of notes 
#1 and #88 are the same
at 1.83 in mm and .54 in grams. However,  the key sticks differ in length by 
10mm, and
the key capstans also taper bass to treble only not as much - more like 3mm.
Example: key front to balance rail #1 = 232mm and #88 = 222mm
              Balance rail to capstan #1 = 127mm and #88 = 121mm
In either case the weighted and measured ratios appear to compare but
the key length and taper of the capstan line are not obvious unless you 
measure or try to decide how
to position the whippen heal to the capstan. A clear need for measuring. In 
addition, #1 has 3 leads and #88 none - measuring cannot detect this.
Another puzzle to solve is positioning the whippen heal to the capstan. As 
the capstan line tapers, should
the whippen heal line also taper to match the capstans? This would change 
the WW value?? Or keep the whippen heals a fixed distance from the
flange center pin?? This would effect whippen travel?? Confused.
Thanks for taking an interest.
Gene

I would have thought the same until the example given by Gene. Seems to
provide a contradiction whereby clearly the weight ratio was the more
dependable. Of course we have to await more info from Gene on this...
but I'd actually like to get to the bottom of what causes the apparent
discrepancy between the two protocols.

Stanwood will be the first to acknowledge that ratio taken his way
versus a distance ratio will yield different results at least as often
as not, if not more so, and he has done some comparative work to find a
happy marriage between the two. But I dont think he's seen such an
extreme example as Gene's seem to be at the moment.

Cheers
RicB

    .....Dale Erwin’s practice of measuring hammer movement for a
    predetermined key movement is much superior for determining the
    ratios. This automatically makes allowance for the vertical and
    horizontal components of movement of every action part. Similarly,
    calculating the ratio from weights rather than distances returns
    more accurate values for action ratios. The problem with physical
    measurements is that it is often difficult to accurately measure,
    visualize alignment, avoid being deceived by parallax influences,
    etc.....

    Frank Emerson