touchweight analysis

[David Love]

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.  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.  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'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'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.

David Love



>From: Richard Brekne <rbrekne@broadpark.no>
>Reply-To: pianotech@ptg.org
>To: pianotech@ptg.org
>Subject: Re: touchweight analysis
>Date: Wed, 23 May 2001 09:10:00 +0200
>
>
>
>David Love wrote:
>
> > Richard:
> >
> > First I replaced the whippens (the old ones were shot anyway) with 
>Renner
> > universal with an offset heel set in the forward position.  The original 
>key
> > ratio was about .61 throughout so I moved the capstan as far as I could
> > without compromising the regulation too much.  I didn't want to go 
>beyond
> > .400 dip and wanted to keep the blow distance fairly standard, thus, I 
>could
> > only get the key ratio down to .57.
> >
>
>Too bad you couldnt get them down a bit lower... but then Jon keeps telling 
>me
>the KR isnt so important. He says the ideal position for the capstan is 
>simply a
>given for any given action. You just manually find it and go with it. I
>understand his point...but on the other hand that leverage at  that point 
>is
>real handy to have if you can get it. :)
>
> >
> > The strike weights were on the low end in bass going to high in the 
>treble.
> > Since the key ratio was fairly high I needed to keep the SW's low in 
>order
> > to avoid excess front weighting.  The bass section was almost right and 
>just
> > needed to be smoothed out.  The transition to higher SW's started around
> > note 33, so starting there I took some weight off the hammers going all 
>the
> > way to the top.  By note 50 I was removing about a gram and a bit over 
>that
> > in the last octave.  The SW of Note #1 was 10.3 and note #88 4.8.  The
> > leading pattern ended up a more standard 3-2-1-0 with front weights
> > comfortably under the maximums as outlined by David Stanwood's table.  
>The
> > action regulated with dip of .395" and blow of 1.75".
>
>I guess they started low. I suppose you had no choice then.. considering 
>the KR
>problem. In the end tho just the smoothing out to a nice even curve is 
>going to
>help alot.  How did you figure your front weights....the old weighing off 
>style
>??. And what did you end up with for a ratio in all this ? I would love to 
>see
>your revised samples values for BW, FW and the rest. Fun to see how others 
>solve
>problems... :)
>
> >
> > The action played much more fluidly with less effort and the customer (a
> > concert level pianist) was pleased with the improvement.  Though I think
> > this was the best solution under the circumstances, it was not the most
> > ideal action.  High KR and low SW's, though necessary to get any kind of
> > normal feel in this action, is not the most ideal solution for me.  The
> > alternative (short of remaking the keys) was to put on an assist spring 
>but,
> > I admit, as someone with a fair amount of pianistic skill, I am not yet 
>sold
> > on how these actions feel.
>
>Stannwoodised actions ?? .. If you do a Stannwood job just right...(and I
>believe that means employing Jon Pages capstan placement proceedure at 
>least as
>a reference if not a determinant) Then they just are wonderfull if you ask 
>me. I
>have done my third now and I am starting to get a "touch picture" in my 
>mind and
>fingers that seems to result from about a 5.2 KR (all other geometry things
>being taken as pretty close to optimal mind you) The S&S I just got 
>finished
>with at the UiB got rave reviews... they just love it. You no doubt made a 
>big
>improvement in the evenness of the action in addition to the rest, and that
>helps one heck of a lot
>
> >
> > Not bad for a beginner, eh?
>
>Grin... a beginner like myself me thinks. Glad to hear of your success. Did 
>you
>ever get any real advice from David S. ?
>
> > David Love
> >
>
>--
>Richard Brekne
>RPT, N.P.T.F.
>Bergen, Norway
>mailto:rbrekne@broadpark.no
>
>

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