Response to Letter to the Editor

[Richard Brekne]

Touch weight

David Stanwoods comments in reply to my article  "Touch weight & Lever
Ratios"  (see June 2003 Journal) contain a few
points I believe should be clarified.

First of all is Stanwoods claim that "Brekne's formula is just a
different slant on the Equation of Balance". This <<formula>> is
BW + FW = ((SW x HR x WR) + WW) x KR,  and while I could perhaps be
flattered by the thought this could be rightfully
attributed to me,  it is in reality a straightforward rendering of the
simple product of the ratios of three levers and their
corresponding weights. It could just as easily have been a textbook
example. The method for adding levers thus goes back
in time a couple thousand years, which of course means that such very
basic methodology is prior knowledge.

The Stanwood Balance equation is not more nor less then a simple yet
very clever piano specific application of that method. It diverts from
it enough to warrant patent protection in itself and that of course
should be respected. It is simple in that its derivation is quite basic
algebra (as described both by Stanwood in his letter to the editor, and
by myself in somewhat more detail at the end of my article). Clever in
that does not utilize the individual ratio values for both the whippen
and shank at all and because it allows for an easy to understand
metrology in addition to very convenient measurement methods and.

Stanwood also states that the below quote from my article is "simply not
true"

     "the overall ratio is the same regardless of whether its taken from
distance measurements, weight measurements, or
     speed measurements"

I can only say that in the given context this above quote is most
certainly true. The fact that differing key dip / blow ratios can be
found to exist for the same Strike weight Ratio simply shows that these
two are measurements of different relationships.  That
does not detract from the fact that the Strike weight ratio can be
expressed in terms of its corresponding distance ratio.
Stanwood himself says as much in a separate article to the Dutch
technical journal and indeed, this distinction was a fundamental point
to my article. That is not to say that the standard distance ratio is
the same as the Strike weight Ratio. These two are different ratios with
different effective lever arms. It does say however, that whatever ratio
relationship is measured  yields consistent results for all three
relevant leverage factors by definition.  It is however,  necessary to
be consequent  in the application of the appropriate force vectors valid
in any given ratio relationship in calculating all corresponding
factors.

An interesting claim is made tho at the end of his letter, where he
states his believe that the "best and most efficient geometry has the
highest distance ratio vs. weight ratio"  I assume the weight ratio is
his own SWRatio, but I am curious to know exactly which distance ratio
definition he is operating with here. Also it would be interesting to
hear more of the justification for this position. Similiar thinking
prompted me to pose a ratio question along these lines just before I
went on vacation that David Love responded to in some detail.

All this being said I would like to reiterate that for very much work
involving reconfiguration of an existing grand piano action, the
Stanwood ratio, method and metrology is by far the best set of tools we
have so far. I encourage one and all to familiarize
themselves with these, and to respect whatever patent restrictions apply
whenever and wherever they are appropriate.

Richard Brekne, RPT, NPTF

--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html