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http://pianopricepoint.com/piano-touch-with-david-stanwood/

The touch equation seems rocket science. David Stanwood had talked the term dynamic touch. But I think this equation has not thing to do with dynamic weight. The point of finger touch the key also changed the touch weight. He had talked about regulate the hammer weight. But, the weight difference from bass to high treble is so huge, should more lead put in the treble hammer? As touch is defined the emotional connection between the pianist and the note played, can this equation deal with the scale design?

May be I am naive and over critical.

What do you think?

More lead is installed in the keys in the bass to offset the weight of the heavier hammers. Balance weight is the important measurement, and is what the pianist really feels.

It is the sum total mass of the action parts and how far the center of these masses are from the pivot point of the rotating arms of the action that determines the inertial properties felt by the pianist. Hammer mass is the most significant part of the system.

Balance weight will not tell you anything about how an action feels when you put it through it's dynamic paces.

The feel of the action must also be in proportion to the dynamic output of the hammers.

My LightHammer Tone Regulation system establishes the mass of the hammer in proportion to the feel of the action. It uses the feel of the action at differing dynamic inputs to determine the weight of the hammer. Tone and touch must be developed together in the tone regulation of a piano.

Velocity of the hammer is enlarged by 5 times. Lead in the key is static balance. If putting lead in the hammer, its real dynamic balance. Is this possible to achieve? Or its not necessary? I think its not too difficult to make hammers from bass to treble has same weight.

What's this? should you release more information?
Thank you.

Adding weight to the treble hammers would cause problems with the tone. Read more about it here: https://www.speech.kth.se/music/5_lectures/conklin/thehammers.html

"The heavier a piano hammer is, the longer it will stay in contact with the string(s). There is a critical region of the piano's compass, between about G4 and G6 on the keyboard. Within this range the contact time of the hammer against the strings becomes equal to the roundtrip travel time for the initial pulse on the strings (Benade 1976). Below this range the hammer leaves the strings before the arrival of the first major reflection from the far end; above this range the hammer normally is still in contact. If the hammer is still in contact at the time of the first reflection, losses occur that decrease the output of the piano and may cause an undesirable quality of tone."

Basically, you want the hammer to bounce off the string fast enough that it doesn't mess with the string's vibration. The lighter the hammer, the faster it bounces back off the string. The higher the frequency of the string, the less time you have for the hammer to get out of the way. Hence, you need lighter hammers in the treble.

For stanwoods strike weight if the hammer set is machined consistently, very minor weighting is needed to get an even weight graduation from bass to treble.

And there's the rub. Too often they are not. What tolerance are you looking for as you graduate the weight?

What I have done is to measure the narrowest hammer in the set an machine them all to that width. I don't taper hammers.
As I use the WNG back checks I use their tool kit to arc the tails - it's more consistent.
Then weigh #1 and #88 and divide the difference by 88 to arrive at a graduation #
As I prefer heavier hammers I have also just weighted the set and not machined them to arrive at a similar graduation.
It's more work but I like the tone better.

What Ed McMorrow said! +1

How the piano works through its dynamic range is the first concern of design, tuning, voicing and regulation. It is a direct vertical gesture mechanically rotating energy through the hammer into the string. The enormous variables of how the action mechanism works at different speeds is of utmost importance. You will find different friction levels, different up-speeds, huge variations of back-check performance and varying amounts of torque and twist of the action parts just to name a few. The trick is to develop the piano's dynamic range with uniformity and a sense of comfort that supports and encourages musicianship.

That's an interesting idea... Why would you use a straight strike weight line rather than a curved, like Stanwood's?

I also use WNG action parts whenever possible, and taper/cove my hammers to the nearest .05g. I use a modified Stanwood curve 6 for most of my jobs. I prefer to keep the hammers lighter in the treble, for the reasons mentioned above. There is definitely a marked improvement in tone when using a lighter hammer. Contact time must always be kept in consideration.

I'm well aware of hammer string contact time.
Hammer type/make and voicing is part of it and I can get great tone out of 88 as well.
I have a technique that works. I understand stanwoods design but have not purchased his tools.
The weight graduation I use is a guideline, not rocket science. As I said. Machine the hammers consistently and the weight graduatin takes care of itself.

Great comments from Philip and Dave. Thanks!

The interesting facts one discovers studying piano touch/tone integration is as the inertia in the action is lowered, dynamic touch weight can rise above the "standard" 50-55 gram range, and that 1-2 gram differences from key to key become imperceptible.

In other words the low inertia regime expands the acceptable tolerances for down-weight.

But it it the pianissimo control that can best be used to "measure" touch. If you have too much inertia pianissimo key speed is forced so slow as to make the action unreliable and uneven.

Just looked at my chart for the last piano action I did and stanwoods suggestion was a strike weight range of between 6.1 and 6.3 grams for note 88 and 13 to 13.6 grams for note #1.
The formula I gave would graduate the strike weights by about 0.8 grams and stanwoods would be very similar with the exception that in the bass there are several notes side by side where his range is the same. His graduations was closer to 0.1 grams.
I chose the top end of the range. And I never have issues with tone or regulation for great control at all dynamic ranges.

Right on, Ed. I'm afraid we too often get caught up with making the measurements match the spec sheet and miss out on the bigger picture and the actual feel of the action. It's common to find Steinways with nicely weighed off keyboards but hammer weights that are off the charts. They're absolutely horrendous to play. After analyzing and correcting any geometry issues and weight prepping hammers to match the action and the belly of the piano, these pianos really come alive. A proper rescaling with Paulello wire also drastically improves the bass/tenor break. Every element of piano design has to be considered. It is all part of the same system and changing one part will affect everything else.

for the example I gave of my use of satnwood recomendations it was on a piano that I designed and built the new soundboard system, new bridge roots, re-scaled, new action, back action and hammers - a bit different than trying to match a hammer set to what one would believe all of these components to be.
and I do have a perception of what its like to hear a piano come alive.
please.