Action Inertia

[Stephen F Schell]

Dear Frans and List,

Placing lead on both sides of the balance point of the key might be
useful in some specific instance, but not as a rule. If equal amounts of
lead are placed at an equal distance from the fulcrum, the inertia will
rise while other touchweight parameters (downweight, upweight, balance weight) will remain unaffected. My general feeling up to now has been that
many (most?) actions suffer from too much inertia, not too little.

Pianos vary tremendously in the amount of inertia their actions possess.
To some degree this is by design, but in many instances it seems to be
the result of key leading at the factory taking place at the end of a
long manufacturing process involving some   w  i  d  e   tolerances, or
a weigh off department operating at the pace of Lucy and Ethel in the
chocolate factory.

David Stanwood wrote excellent articles for the October and November 1990
Piano Technicians Journal. He also provides comprehensive handouts at
convention classes, but they are all copyrighted so I cannot provide
copies. He Lives in Vineyard Haven, Massechusetts, and can be contacted
at (508) 693-1583.

Chris Robinson wrote a great series of articles many years ago which were
published in the PTJ, although none dealt with action geometry as I
recall. Best sources for his wisdom are the classes he teaches.

..
Steve Schell
stfrsc@juno.com