touchweight analysis

[Richard Brekne]

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