Stanwood Touchweight

[Richard Brekne]

Farrell wrote:

> I'm trying to knaw through my first go-round with the Stanwood Touchweight
> system.

Good for you. I think you will find the whole process quite the eye opener.

> I want to do as much myself as I can. My plan is to do the SmartChart method
> on my own, then pay the $150 and see what Bob Marinelli at Pianotek comes up
> with. I want to understand as much as possible.
>
> I'm doing my work on my own piano, a 7 year old Boston GP178 (5' 10" grand).
> I have made all my measurements. I have followed the instructions on page 5
> "Component Touchweight Balancing with the SmartChart" sucessfully up to
> step 6 - Using Strike Weight Ratio results along with the existing Strike
> Weights to determine the new Strike Weight level................  I am
> totally lost at this point.

To begin with, getting good results with this is not going to work unless you
start getting really, and I mean really into action geometry. There is a good
series written by Bob Hoff in the last 4 Journal issues (October not included),
and some good stuff in the journal reprints. My comments below in no way are
official, but based on my own observations and conclusions so far, as I have not
yet had the pleasure of taking Stanwoods licensing course. Also read through
Stanwoods articles in recent Journals as well.

> Am I supposed to average Stike Weight Ratios and
> use that - or use individual ones for the few keys that were measured?

Strike Weight Ratios are going to be to some degree the result of the process,
andwhich to some degree a parameter to choose ahead of time  Remember, this
whole process is partially an answer to the problem of weighing off the keys....
as well as addressing the question of action leverage. The action geometry is
optimised for a certain leverage and the hammers are manipulated so as to have a
very even and graduated Strike Weight. The maximum amount of front weight for
each key (see the table in the kit handout) then stands in relationship to these
parameters and the Balance weight spec that has been choosen..

> Average or individual Balance Weights? My Wippen Balance Weights are between
> 9.1 and 9.9.

This isnt far off from Stanwoods general specs, but what are the components of
these. ? You cold feasably have  have a WBW of 9 and still have a major problem
with key ratio.

> The Stanwood graphs of Strike Weight VS. Strike Weight Ratio
> specify a WBW spec of 9.0. Does this mean mine are bad? Is the 9.0 some kind
> of target? Where does the 9.0 come from and what do I do with it? I am
> totally lost with what to do with what in this area.

9.0 seems like a target to me as well, and I believe it is achieved by
manipulating the key ratio, and eventually the whippen cushion position if
neccessary. This is one spot you need to know your action geometry well. Where
ever the contact point for these ends up, it has to be on the magic line, which
assumes you have the correct spread (spread being set by disregarding the
existing magic line and paying attentiont to the top action relationships). This
spot also has to be able to lift the whippen assembly for a given key dip so
that the jack clears the knuckle at letoff, but doesnt get buried in the stop
felt at drop. Getting how to accomplish this clear in your mind is at first can
be a real head scratcher. Just keep thinking it all through.


> Then on the same step 6 is a note that addresses what to do if your Strike
> Weight Ratio level is undesirable. How do I know if my Strike Weight Ratio
> is undesirable? What makes one desirable and another undsireable? My SWR are
> between 5.1 and 6.0, with an average of 5.77 for the six notes measured.

Not being a licesensed Standwood installer myself, I dont have privy to this
info, and I havent gotten so far as to figuring that part out yet either, yet
you can accomplish a lot and learn a lot by graduating the strike weights to
conform to one of the charts (probably wise to pick a middle of the road chart
at first... grin), setting the spread, moveing the capstan / whippen contact
point to conform to the magic line and whippen assembly travel needs, and then
weigh off for the balance weight you want.

This is the way I am starting off anyways, as I want to understand as much as
possible before going to take Stanwoods course. I get the feeling that action
geometry, leverage and what can be done by manipulating  these are far to little
understood by most techs. I was always good at the old.... "make it work"
approach to action regulation, yet I often ran into actions that just wouldnt
cooperate.. and now I am beggining to understand why, and what to do about it.

> Anyone care to share some knowledge? Also, does anyone have a copy of
> Stanwood's June 1996 PTG Journal paper "The New Touch Weight Metrology" -
> that might help quite a bit - depending if procedural details are in the
> paper. Thanks

Order these direct from the home office. Contact Sandy Roady, or anyone else you
know there and they will help you with this.

>
>
> Terry Farrell
> Piano Tuning & Service
> Tampa, Florida
> mfarrel2@tampabay.rr.com

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway