Howdy Sy, it's good to see you on board (line).
I'm sure you will get various responses to this question, but here's
both my understanding and theorizing.
Providing all other conditions are equal, i.e., quality of parts,
tooling, etc., then...
. I have no feelings or emperical evidence to support "faster
repetition", etc. (but read on...).
. I feel that the butterfly spring is less expensive to build and
assemble -- at the *parts* level. It could be argued whether any
savings is offset in labor intensity (regulation).
. It has been said that the regulation of the Scwander-type is easier
and faster to perform, but that adjustment is required more *often*
than with the butterfly style. I've not personally noticed this, but
admit to not having paid much attention to it.
_________
. I do not believe Kawai changed to copy anyone. If you recall, they
also made major product and action parameter changes during this same
period: action rails, action spread, hammers, keyframe, and so on, to
coincide with different plates and scales of the [then] newer GS
models. From that point, it probably became more feasible to
incorporate these changes into the KG and other series. I believe the
wippen/repetition spring system change was integral to this, as
opposed to an isolated or arbitrary change. Although the action spread
was increased by several millimeters, I cannot speak to the design or
engineering concepts -- perhaps the wider the spread, the less
efficient (or practical) the Schwander-type assembly becomes?
. The factory workers *hated* the change, and the first few
off-the-boat offerings following the change showed this contempt. The
tension was either insufficient, or was too hot. Later they became
more consistent. They'd been doing it one way since 1928. They, like
us, are resistant to change. And they, like us, had to develop the
proper service techniques.
_________
As far as regulating the butterfly springs, we are not required to
enjoy it. We simply must grin and bear it. I've tried all the methods
and tools that have been presented to make the process more painless.
I always return to the method taught me by LaRoy Edwards...
Use a regular, straight, spring tool (the kind with a 'v' for the
business end -- depending on which way you hold it). Supply houses
carry these, or you can make one from a clothes hanger or other soft
stock. The 'v' is used to snag and remove the wire from the lever
slot. Then, the *coil* tension may be increased or decreased, using
either the tool or by hand, depending on the amount of adjustment
required, without contorting the curvature of the spring. Either way,
you're always holding the tool until you're finished. Use the same
tool for installation. Rest the curve (highest part) of the spring
just under the lever "shelf". With the *side* of the tool, press
against the *side* of the spring, causing it to snap (and
automatically seat) into correct position. If you're interrupted with
a phone call, leave the tool resting diagonally between the repetition
lever and the wippen beam to mark your spot.
After 10 minutes of practice, this method becomes so fast that it's no
problem to retrieve the spring, make adjustments, and continue. With
more practice, you develop a feel for how much adjustment is required.
Thus fewer in/out/adjust cycles are required.
The only time I have problems with this method is when I must undo the
work of others -- including that from some factories! As long as the
springs were in the ballpark initially, and providing I'm the first on
the scene, all goes well.
Regards,
Jim Harvey RPT
Greenwood, SC
________ Reply Separator ____________
Why are so many piano makers still using the butterfly type rep. lever
spring? The other kind is sometimes called the Schwander type (Sch). It
seems logical to me the Sch type would be superior to the Steinway type
butterfly. Look in the piano supply catalogs to familiarize yourself.
This PTG archive page provided courtesy of Moy Piano Service, LLC