[pianotech] Vertical Touchweight

[Floyd Gadd]

List,

I've now completed the rebalancing of the keyboard on my 41" 1965 Heintman,
using targets derived from my measurements on a 42" 1984 Yamaha LU101.

It was an interesting project, and I'm pleased with the results thus far.

I used exclusively the 1/2" and 7/16" diameter weights, though I had the
5/8" weights.  The back two inches of the keys were narrow enough in their
vertical dimenson that 7/16" was the largest weight that could be
accomodated there.  The only time I had to place a weight that far out was
at the ends of the keyboard--in the bass, because I was using a higher
target of 55 grams, and in the high treble, where my target was 50 grams.
FWIW, I used the target of 46 grams in the middle of the keyboard, as was
recommended to me here by Jeff Deutschle.

What I found interesting (and somewhat disconcerting) was the lack of
consistency in where I needed to position the weights.  I think this would
be due to the influence of the hammer return springs, which must have been
exerting uneven tension across the scale, even though they lined up with
each other when the spring rail was out of the piano and not under tension.
The damper springs, of course, where taken out of the picture during the
weighting process.

I've a bit more regulating to do before I get a really clear picture of what
I accomplished (or didn't).  I still need to regulate the dampers to the
keys, fine tune blow distance/aftertouch, and fine tune the letoff and lost
motion adjustments.

Here's my question:  Do any of you have a method for establishing a
consistent adjustment of the hammer return springs?  Bending the springs is
relatively easy.  Identifying a measurement methodology and a target value
is new ground for me.  I would think, given my experience here, that
attending to the spring issue should come before any messing around with key
weighting.  I'm familiar with the procedure for adjusting the repetition
springs on a grand, but I've not seen a procedure outlined for vertical
actions.  I done a limited amount of reading in the archives, but have yet
to find anything systematic on this issue.

Any suggestions, or pointers to old journal articles or specific postings in
the archives?

Thanks for any help you can give me.

Floyd Gadd
Manitoba Chapter