Hi Gene
Increasing leverage, that is to say lowering the ratio, will as you
found increase your blow for distance at the expense of BW. But looking
at your posted numbers you dont really have a problem with an increase
in BW that cant easily be taken care of by counterweighting with a bit
more lead in the keys. An increase of 4 grams in BW can be offset with
a similar increase in FW and still keep you at moderate levels of key
leading. You'd end up with 34-36 grams in the bass which is like 6
grams under Stanwoods FW maximum tables for what that is worth.
Jon Page pointed out something to me that has stuck with me ever since.
Get the action geometry right first, then balance it. You want a default
key dip of around 10.0 +/- 0.2 mm and a blow distance of around 46 mm
+/- 1 mm for correct letoff/drop and aftertouch. This gives you all
kinds of room to maneuver when regulating for different pianists key dip
preferences. Once you have your action geometry right.... Balancing ala
Stanwood is the perfect next step... because it yields fixed known
weights at both ends of the levers. Once you have that knowledge, and
resultant variance in BW from key to key is the result of some ratio
variance key to key... like position of knuckle, capstan, heals... etc.
and you can rather easily find these problems and correct them So not
only do you even out SW and FW, but you identify, and correct unevenness
in R as well.
Key Ratio taken Stanwood style is done with the key level. So distance
measuring along the top of the key instead of the way its usually done
(top front down to balance rail at the pin and up again to the capstan)
gives the same results as in the horizontal position all weight values
are vertical forces. Course this changes when you move the key, but
thats the same in anycase. If you measure distances the usual way, you
may find a slight difference... or not.. but you have to be sure your
measurements are very very accurate. 1/ 1.83 = 0.54~ btw.
As long as the stack is aligned correctly over a straight line of
capstans all yielding the same KR, and the heals all the same distance
from their respective flange centers, there will be no difference in
effective WW. For any key with a 0.5 ratio, a distance of 10 mm movment
at the front will result in a 5 mm movement in the opposite direction at
the capstan so whippen travel will remain constant.
Seems to me if you can find an acceptable way of increasing leverage
then you should do so to get into usual ball park figure for key dip and
blow. THEN re-address your BW by adding what looks to be moderate
levels of key leading.
Cheers
RicB
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 = 232 mm 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
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