Action Geometry Correction

[David C. Stanwood]

>Should someone else have the formula (and a scanner) I would be most
>appreciative of receiving this.  I wasn't able to attend Providence but hope
>to show my funny face in Kansas City.   Action spread is usually around 4
>13/32" right?  David Stanwood has mentioned in previous classes that
>generally the spread isn't as big an issue when calculating overall
>leverage....I guess the next question would follow (maybe Jon and others can
>answer):  If the spread is greater, say 4 1/2", exactly how will this affect
>the Strike Weight Ratio?...or would the differences exist...still
>thinking....in whip ratio?...Trying to sort this out.  Can we make a
>significant difference in the leveraged system as a whole by altering the
>spread?  (There, got that out of my system).
>
>Thanks for reading,
>
>Blubbering hammer head
>Dave Swartz, RPT
>dms2000@majesticpiano.com


Hi Dave,

As I've said before,  ask me the last time I modified action spread....
answer:
It's been a while.  I think that fixation on action spread is way overrated.
The big issue as far as I'm concerned is over all action ratio which can be
assessed
as an average weight ratio level using the new touchweight metrology or by
accurately 
measuring key to hammer movement ratios.

We've had astounding results making by making strike weight ratio to
specification.
This is not only from my experience but from the collective experience of
the 14 technicians 
who use my technique.  We find this factor to be highly variable in all
makes and ages of 
pianos, especially Steinway because of the wide variations in KEY WEIGHT
RATIO.

It all boils down to specification.  Spread should be to a specification
plus or
minus a reasonable amount.  Same goes for any other parameter you can
identify such
as hammer weight, strike weight, front key weight, and strike weight.  At
the end of
the list of importance is down/up wt. which unfortunately is traditionally
at the
top of the list.  

Traditianal specifications aren't specific enough so we have big variations
in our actions.
Measuring hammer weight to the nearest pound is a striking example of this.

To answer your question I think it would be very interesting to have data
on the effect that 
changing spread has on leverage.  Don't have enough data myself to give you
an opinion.

David C. Stanwood