Grand touch

[David C. Stanwood]

Dear Kristinn,

Reducing the striking distance would be at the bottom of my list of
choices.  Actions may be made light enough by other means. 

I would add that an ideal range for friction weights ((D-U)/2)) would be 15
grams in the bass tapering down to 10 or 11 grams in the treble.  Plus or
minus two grams from these norms is an acceptable variation.

A commonly overlooked friction source is key bushing friction.  The most
accurate way to measure this is to take the stack off the frame.  Take the
key to be checked off the frame and pivot it on a wedge.  Arrange lead
weights on the top of the key so that the key is neutrally balanced.
Without removing the weights, place the key back on its key pin and test
how many grams of weight placed on the front of the key that it takes to
make the key go down.  For example, if it takes 7 grams, then that means
that 7 grams of the downweight is due to key bushing friction, and the same
amount inhibits the upweight.  I would classify key frictions as: Low
0-3grams, medium 3-6grams, high 6grams or higher.  It is recommended to use
dry teflon lubrication in all cases for key bushings.  This also lengthens
the life of the bushing by reducing wear.

As to the wippen assist springs.  There is a way to check how hard these
are working...   both up and down weight will rise by essentially the same
amount if the spring is disengaged.  To check how much the spring is
working down the touch weight, measure up weight with the spring engaged
then disengage the spring and remeasure.  The difference tells how hard the
spring is working.  In my experience, 25grams is about the limit for a
0.7mm spring.  Although springs can work as much as 45 grams off the touch
weight they cause "bouncy key" when working at the extreme.

A problem with Samicks is that they were balanced with the springs engaged
without particular regard for how hard the springs were working.  We've
seen keys with springs working hard and back leads in the key in the mid
section of the piano.  NOT IDEAL.
If the touch weight with the assist springs off is uneven then the key
leading will be uneven.

I disagree with the suggestion to make the repetition springs tight.  I
agree with Stan and Ed that a controlled rise of the hammer when released
from check is a good standard for adjusting the spring.  Tight repetition
springs can cause double strikes on light blows and they erase subtle
feeling for pianissimo dynamics.  As Ed says, the repetition spring works
against the mass of the hammer to lever the key upwards at the front. I
say, a light hammer with lots of key lead will repeat poorly.  A heavier
hammer with lower key leads will repeat faster.

As to lightening the hammers.  Taking a gram off will make a huge change in
the feel of the piano.  If you have a digital scale, take the hammer shank
off the rail. Throw it on the scale and set the scale to zero.  Do your
weight reduction and check how much weight is taken off by putting it back
on the scale.  if it reads -0.7 that means you've reduced hammer weight by
0.7 grams.  As to removing weight by filing felt off the hammer, I would
take the approach of taking dimension off the sides of the hammer down to
11.0 mm if needed.  You'll get more weight off by working the sides than by
filing the hammer or removing wood from the tail.

So Kristinn, did you take any up down weights that you can share with us?
With and without the assist springs hooked up would be helpful.  Also, how
much lead is in the keys?

David Stanwood