Touch Weight

[James Ellis]

Here are a few comments following the latest posts on related subjects.

Richard,
I was using the term "touch-weight" to refer generally to the static
measurements, "doun-weight", "up-weight", "balance-weight", and "friction",
of the total action (minus the dampers) as these appear at the key front.
I do know what "balance weight" is.  We say "weight" because that's what we
use to measure these forces at the key fronts.

Paul Legard, 
Paul would like all the confusion to be removed from this discussion, and
for us to provide him with a simple soultion for optimizing an action.
Paul, try this.

1.  Start with a well-designed action.  Re-designing an action is not what
you are wanting to do.

2.  Use hammers that are uniformly graduated from bass to treble - no large
or sudden variations in size or weight along the way.  That will give you
hammers with evenly graduated mass, bass to treble.

3.  Use the recommended parts for that particular action.  We assumed a
well-designed action to begin with, so maintain the original design,
ratios, spread, clearances, etc.

4.  Check everything for friction, beginning with the keys alone, befure
you go any further.  Keys free to move - no binding - very tiny bit of
side-play at the front bushings - barely enough to feel - no more than that
- no side slap - no binding - no "pulley keys".  Check everything else.
Everything snug, nothing loose, but nothing binding, jack centers
absulutely free.  Don't worry about whether the shanks are round or
octagonal.  It won't matter, as long as you stwy with the correct
dimensions and high-quality parts.  I'm talking about the keys and action,
not the back-action or dampers.  That's another matter.

5.  Do a preliminary action regulation.  Double-check for any possible
problems, especially any tight centers or bushings, or anything loose.
Deal with all that stuff first. 

6.  Weigh off for even BALANCE WEIGHT (down-weight + up-weight / 2).  The
actual balance weight I aim for will depend upon what the piano owner
wants.  If you have done the preliminary things well, you will find that
there won't be any big differences in balance weight and up-weight from key
to key after you check the down weight.  There will always be some.  But if
you aim for even balance weight, you won't be way off when the friction
changes, as it will surely do, sooner or later.

If you follow this routine, you will end up with an action that has an even
response from bass to treble.  But if you start with hammers that are not
uniformly graduated from bass to treble, and friction that is not
consistent, and then try to compensate for it with the key leads, I can
assure you that you will end up with an action that does NOT have a
consistent feel from key to key.

David Stanwood has a patented system for doing this that we have all read
about or seen.  I have my own system, different from David's, that I was
privately developing when David first come on the scene.  Mine is still
under development, so I won't go into it right here on this list.  I have
not yet decided what to do with it.

But Paul, if you will follow the simple procedure I outlined, you will end
up with an action that is consistent from bass to treble, and you will not
infringe upon anyone's patent claims.  You will just be doing what has
already been done for years, but you will be doing it well.  From time to
time, some manufacturers have not been as careful as they should have been.  

The problems I often find in old pianos are:

1. The hammer weights were not uniformly graduated to start with.
2. The friction was not uniform to start with.
3. The factory tech tried to compensate with key leads.

The result was that the down-weight might be even, but the key-to-key
action response would not be even throughout the dynamic range, and no
amount of regulation would make it so.  Furthermore, when the friction
changed, the down weight would be uneven.

Sincerely, Jim Ellis