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see for instance that the hammers at rest have a 16-18° inclination , so the mass of the hammer locates differenly depending of the hammer travel distance, hammer bore and rake angle, the mass of course is then higher with tall hammers (they are raére those days)

reduction in leverage at the roller level during stroke will depend of the roller size but also the height of the hammer center location in regard of the spread line.

I was told once that a Renner action that have a good mechanical setup, will react at each gram added, for instance, the hammer raise a hair with 48 g a little more with 49, 50 , etc.
In any case that shows how the "down weigh" is evolving during the stroke (which is expected, as we have a ratio change occuring)

A well balanced action will rise slowly and evenly under the exact weight, but that weight progression is certainly something we could examine and use.

All I can say is that I've played two actions with the adjustable system installed. Both tuned, voiced, and played very nicely. I didn't have the time or the inclination to change the settings so I don't know the extent of variations available. The Steinway "D" is one of the most responsive actions I've ever played.

Keep in mind that the Standwood adjustable action is not the same thing as the Standwood Touch Design modification. The adjustable action is much more expensive and offers the ability to change the weight of the action whenever you like, whereas an action that has been treated using the Stanwood Touch Design approach is one which has been measured, calculated and regulated to perform at its best - presumably with input from the customer as to what characteristics they are looking for.

@Gene. Yes weight progression can be nice from the start.
What is useful is to locate the SW range.
The bass hammers are generally thinner, on European pianos I heard you prefer them the same size than treble.
That should add some mass . Is it the case ?
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The only time that I can imagine a need to have thinner hammers in the bass than the tenor/treble is for spacing. When the hammers are bored to come close to or match the angle of the bass strings, spacing may become an issue but I don't angle much more than 6 - 8 degrees regardless of the string angle so there is no reason to have thinner hammers in the bass.

I would guess it is mostly for tone reasons, so the basses are not covering the mediums too easily.

it may also help with weight, avoiding too much lead in the basses.

Specifically, the adjustable action offers variable inertial resistance and hammer velocity. May or may not be appropriate depending on other aspects that Stanwood system doesn't reveal. I'm aware of one that has received decidedly mixed reviews.

Measurements and calculations of Stanwood Touch Design are not reliable -- again, because of factors that are not measured or taken into account.

Greetings,
David Stanwood woke us all up to a level of quantification that I wasn't aware of before, and I haven't seen an action yet that the application of even some of his ideas doesn't help, (even though I use a different approach, the instructor that taught both of us mistook my action for his when he played it).

What works for me is a pair of curves. One is the front weight of the keys, which, if not consistent, will cause inertial discrepancies during fast play that nothing else will correct. The other is the strike weight, which can vary a very slight amount if necessary, but in a perfect world would be as even as FW. However, the 88 individual ratios in the action must be consistent for these two curves to be mated in such a way that the response is even. This is where the quality of the parts enters into the fray, since in terms of even response, the consistency of the parts is a prime parameter.

What I have found is that the WNG action parts produce the most consistent set of ratios, key to key, I have ever seen. (I am not a dealer or agent for any brand of parts, and I have used them all of them over the decades). Their lack of variability makes building actions with them far more consistent, and it shows up in how closely the two curves can be left at their ideal consistency when the action is assembled. Get the right match and you get beauty. The imperviousness to humidity is a strong asset in the school environment, where keeping 130 pianos on budget is much easier without having to constantly re-space, travel, burn, or tighten the actions. That the pinning seems to be far more stable than the cloth is also a plus. This is another type of "performance" that has to be considered, too.
regards,

I have an adjustable action STD and consider it the best investment I've made in the instrument. It gives me as responsive an action as any I've played on other grands, it's made my playing much better, and if I wish I can make the weight heavier or lighter on any note or range of notes by adjusting the magnets front and/or back. As a customer, it is irrelevant to me whether the measurements and calculations are accurate enough - the action and end result are proof enough that the system works.

It seems like you are after the piano equivalent of a Grand Unifying Theory in physics - and if you are, I applaud you for your ambition. But even though there is no GUT yet, it doesn't stop physics from advancing and producing very useful results. It might also be that Mr Stanwood is well aware of what is not in his theory but chooses to leave it out because he is working with what he considers to be the most important variables. I have no affiliation with Stanwood other than I've met people who swear by the work he did on their actions - and in particular the evenness and touch. If he were really leaving out such vital details, I fail to see how he could have produced such good results.

I believe Stanwood's measurements are very reliable.

The various technicians using the measurements make choices I disagree with.

But, the measurements themselves, reliable and useful. Again, depending on HOW you use them, determines the feel of the action.

Now, SALA changing the inertia of the action ?? I suspect, not at all. Changing the pianists leverage against it ... maybe. Velocity differences .. again totally dependent on the pianist.

Perhaps one of the engineers that post here can elaborate?

Not a logical statement. Keep in mind I never said they were all failures. There are certainly a greater-than-random number of successes out there from folk using those formulas -- and you appear to be one of those.

What I did say was that the process is not reliable -- that is, its use does not guarantee either correct diagnosis nor accurate prediction of actual response. Sometimes it appears to work. But sometimes it definitely doesn't.

If something is truly "proof", it will always be repeatable-- or we will understand why it doesn't. There are people that are not happy with certain instruments that have had the same treatment that worked in other cases.

Stanwood made a great contribution in getting people dealing with action geometry issues. However, the limitations are becoming more apparent as time goes along. We have further work to do to isolate all the variables that affect piano touch.

I'm not going to argue that you're wrong, but I do think it is important to remember that with the Stanwood TD, as with anything else in piano work, the end result is largely due to the skill of the technician performing the task, as well as the desires of the owner. I've played a lot of Stanwoodized pianos (in addition to my own) and they all feel different, and I feel like that the results are largely due to the goal of whoever was doing the work. Mine is kind of a "middle of the road" touch, but I've played some where you could practically blow on the keys to make them play, and I've played others that feel like mine. Now that the Fandrich-Rhodes thingy is out, that is definitely the service I will offer my clients.

The Stanwood process is a tool. It is a well thought out and accurate tool.

Like any "tool", it is only as effective as the person using it.

To suggest the responsibility lays in the tool, is disingenuous and misleading.

I will agree that knowing how to manipulate that particular tool does not insure the technician will apply it appropriately.

It is neither well thought out nor accurate:
*It involves assumptions that are contrary to basic physics.
*It substitutes precision for accuracy.
*It fails reliably to predict actual touch experience.
*It is based on static measurement of "what's happening
when nothing is happening" rather than dynamic events
that unfold as key and hammer actually move.

It provided an excellent application of the formula to determine weight-scale accuracy to friction in piano actions. But it is time for us to recognize the limitations of this procedure which served well to introduce many to action touch issues and move on to other more valid and effective approaches.

Stanwood recognized the importance of strike weight and action ratio in determining how heavy a piano action feels. However, as far as I've seen, he offers no analytical basis for his observation. That is certainly the case in his patent, in which he only describes static balance, or, as he calls it, his "equation of balance." He seems to claim some proprietary ownership of that equation, which is a bit absurd, because calculating the static and inertial forces in a lever system is simple physics and has been understood and applied for many, many centuries.

As it turns out, strike weight and action ratio are the primary determinants of an action's moment of inertia, which can easily be shown by some simple math. I have done this math and published the result on the internet for anyone to see. Fandrich-Rhodes seem to explicitly recognize the issue of moment of inertia, which they are calling the "inertial touch force," and claim to include software that can calculate it. Given the straightforward and well known method of calculation, I would have no a priori reason to doubt their claim. They further claim that "nothing has been written about how to identify, quantify, and correct inertia problems in the grand piano action," which seems to be a bit of a stretch. My published analysis dates back to 2007, and surely can't be the only one in existence.

I will reiterate, it is a well thought out tool.

Unfortunately, many technicians place responsibility for failure on everything but their own experience.

Understanding what pianists need is a matter of considerable experience. More than most know or are willing to admit.

Stanwood's "tool" is not a substitute for that experience.

In my opinion, true client satisfaction comes best when "tools" are applied wholly and completely for the benefit of the client.

As a related example, we see failures at the clients expense when we say "such and such" replacement piano hammer is the BEST and ONLY one for you.

The reality is, that hammer is the one the technician has the most experience with or benefits from selling. Neither of these treats the client unbiasedly and only benefits the client serendipitously.

Stanwood's work has suffered the inexperience of a great many folks using it.

Truth is, in the right hands, any tool has value. In the wrong hands, no tool has value.

Greetings,
What am I missing? I have always kept the key weight (FW) as a prime component of the inertia a pianist deals with. Those leads move before anything else in the action.

SW and action ratio combine to define the resistance the key must propel, however, the research (Anders-Askenfeldt) shows that the key is often on the punching before the hammer has finished accelerating. My logic is that the mass of the key determines the first resistance the pianist feels, and that resistance increases rapidly, (geometrically? exponentially? logarithmically? somebody help me out here..) as the force applied increases. A heavy key gets hard to play at high speed, regardless of what is sitting on the back of it.
Or, was something else intended by the post?
Regards,

Can you direct me to the location?

According to Fandrich and Rhodes' research, strike weight is the overwhelming source of inertia: measurements from note A49 on a Steinway B revealed that the hammer was responsible for 81.8%, followed by the key (10.1%), lead weights (5.6%), and wippen (2.3%). Removing .6g of mass from this hammer reduced the overall inertia by 7% and a 4mm capstan moved reduced inertia by 14%. Altering the lead weights produced a nominal effect, except for removing them altogether and installing a strong turbo spring, which reduced inertia by 6%.

They're also supposed to be doing a multi-series article on their research in the Journal, hopefully starting this month, which should answer many of our questions.

Sorry, but it's not the key weight that dominates. As felt by the pianist, the moment of inertia of the hammer and its shank gets multiplied by the square of the action ratio. Let's take a typical action ratio of 5.7. In that case, the hammer's moment of inertia, as felt by the pianist, would be multiplied by 32.5 times.

I think people often assume key weights are the problem because lots of key weights are required when hammers are heavy and/or the action ratio is high. You might say key weights are an indicator of the problem rather than the problem itself. You can read my derivation here . If you can find a mistake in my math, I'll be happy to change my mind.