touchweight analysis

[Farrell]

> ...... I got keyed into
> looking closely at the knuckle. Some were really slanting badly... mostly
> towards the hammer. Straightening these up solved quite a bit of problem
keys.

I had not heard of this. (I suppose I just missed it somewhere.) Are you
speaking of the slot in the hammer shank not being at right angles to the
long axis of the shank, resulting in the knuckle core being angled back
toward the hammer - thus effectively increasing knuckle-to-centerpin
distance and reducing leverage?

----- Original Message -----
From: "Richard Brekne" <rbrekne@broadpark.no>
To: <pianotech@ptg.org>
Sent: Wednesday, May 23, 2001 6:50 AM
Subject: Re: touchweight analysis

>
> David Love wrote:
>
> > Richard:
> >
> > To do the weigh-off I now use Stanwood's Balance Weight/Friction Weight
> > Table.  It effectively takes the friction component out of the weigh-off
so
> > that any variations in downweight through the keyboard can be directly
> > attributed to friction.
>
> Thats really nice isnt it... the predictability that creates is ...just so
very
> very handy indeed.
>
> > With relatively light hammers, the friction in the
> > action was lessened, and because the KR made the action feel like it was
> > fighting you a little, I weighed it off at 34 BW.  I think it was the
right
> > choice for this pianist.  I didn't hear directly from Stanwood, I
usually
> > copy him directly on these types of queries, but did not on this one.
Jon
> > Page, however, was very helpful, especially in terms of a methodical way
of
> > establishing capstan location.
>
> Yes.. tho I am rather green at this myself,  I have come to rely on Jons
idea
> for capstan placement quite a bit. At the very least it creates a sort of
window
> you dont really want to go outside of unless you are prepared to deal with
other
> problems. Keydip, sharp travel, blow distance, and the like. Course you
can
> always create a situation on purpose and this whole idea lets you do that
rather
> conciously...
>
> > The last two actions I've done have been a
> > crash course in Stanwood's method of problem solving.  I have found it a
> > very useful way of quantifying the problems and plugging in possible
> > solutions.
>
> I aggree one hundred percent.
>
> > I've recently set it up on an excel table with the formulas
> > programmed into the individual cells so all you have to do is plug in
the
> > numbers.
>
> I did too... right off the bat on the first run through. It takes FW, KR,
WRW,
> SW, UW, and DW as parameters and spits out the rest. You can see just how
the
> ratio to BW developes, and just how much a role friction plays. I think
this is
> what helped me get such an even BW and Ratio in that last job I did. In
> essence... after getting  nice SW and FW curves that in theory should
yeild an
> acceptable Ratio... I dinked around with evening out friction as
neccessary to
> put the final touch on things. Friction ended up being pretty even too
really,
> tho to be honest I had to cheat a bit with hammer flange tightness this
time
> around. Still they were all within a 7 to 4 (-) swing window and also
reacted
> well to the S&S tap test. Btw, in the course of that process I got keyed
into
> looking closely at the knuckle. Some were really slanting badly... mostly
> towards the hammer. Straightening these up solved quite a bit of problem
keys. I
> hadnt been able to get the BW high enough for these...had to look around
to find
> the problem.. and there it was...
>
> > I'm sure someone has already done this but going through the
> > excercise of setting it up gave me a better sense of how all these
things
> > interact with each other.  I'm working on a "what if" table that
combines
> > research taken from Richard Davenport to produce an input/output table
so
> > that various solutions to problems can be tried on paper first.  I
haven't
> > plugged in the new data from this particular action yet, but when I do
I'll
> > send it off to you and you can look at the before and after if you're
> > interested.  Speaking of Richard Davenport's research, if you have his
"What
> > happens if" table, take a careful look at under centering versus over
> > centering, and what that does to the touchweight and friction.
>
> I dont have that, and havent read anything from Richard... would love
to... do
> you have anything more on this ??.. I can send you my excell whatiffer if
you
> like for ideas..
>
> >
>
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:rbrekne@broadpark.no
>
>