Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Key Dip Block, how do I get/use the right one?

Mark if your interested in the angle on top surface of the block its 2.3 degrees for most pianos. This is based on a 9 1/4" length of key from the balance pin to the front and a 3/8" dip. Another way to make the block is to have one end narrower by .025" for every inch of block length.

Thanks, Emmery.

The numbers you posted give a ratio of 1:25. By my sums, this means that the block should be narrowed not by .025" but by .040" (or 1 mm) for every inch.

You are correct Mark, my apologies. I had the fraction inverted and was dividing 9.25/.375 instead of the other way around.

My previous point about aftertouch may have been misunderstood. I look at after touch simply as a range of needed reliable mechanical function. That is what its purpose is, and that is what we need to set it for. Being consistant on a setting within that range is also easy to do and if pianists are sensative to it, all the more worthwhile. The safe reliable mechanical function does trump a pianists preferance for feel regardless of who gets blamed. Imagine the horror on a performance if a slow passage is highlighted with double strikes where there sould not be any? Poor checking, double striking or jamming a jack into its cushion is not an option for our work. From a horse and cart perspective, aftertouch came into existance not because pianists asked for it or needed it to do their tonal/touch voodo work with.

We are talking in the range of ~1mm movement, give or take ~half a mm to achieve the desired safety margin. If pianists believe they can tell the difference of +/- the thickness of a piece of paper on a key bottoming out on a relatively squishy punching I got news for them, we don't get much better than that when we eyeball a guage to set it. Personally, I find some pianists more fussy about the density/squishyness of the front punching than the actual amount of aftertouch.

It is possible to move out to the edges of the working range
when setting aftertouch, and to this end we can accomodate a pianists preferance. Its a waste of time and money to start altering action geometry to go beyond that small range in my opinion.

(ADDED) I'll mention something else which hasn't been mentioned by others. Aftertouch also syncs together the initial attack sound of the note with the bottoming of the key. That extra .025"- .055" of key movement occurs in about the same timespan as it takes the sound to reach your ear from the string....~ 2-3 milliseconds.

One could make a block that can adjust to various angles by cutting a slit in the block and using a set screw to change how wide the slit is.

I used to use some home made shims for many years to set aftertouch and now have what I think is a better method. I will set up a few key samples for ideal functioning. After this is set, I have a 14 oz weight set flush with the key front. The weight has a flat lip machined in it that over hangs and a finger type (not plunger) dial indicator tip is set under this lip. The key is dropped until escapement and I check the reading on the dial. Then I let the key settle with the weight and recheck the additional reading on the dial. The heavy steel dial indicator base rides the key slip as I move along. For black keys I do the exact same thing but find its easier to measure the additional uplift on the damper heads after escapement. It saves a little time in the end.

I believe that the bottom of the key surface does not settle the same way on a punching as it does with a shim in there. If you look closely at a used punching there is an uncompressed hump running up the middle of it about the shape of the key mortise. If you doubt that, turn the puching 90 degrees and see how it effects your measurement, you will be surprised. A shim gage will not properly simulate the exact contact area the key makes with the punching. It will also have less area of contact since there is a piece slotted out of the front of it in order to get around the pin.

Aftertouch is not a "one size fits all".

There is a range of optimal results based on the pianist.

The most important relationship the piano technician has is with the pianist, then the piano.

Aftertouch most definitely effects the sound of the piano.

How so? If you reduce or increase the aftertouch, what would be the difference in sound?

I suppose theres a bit of leeway within the window of mechanical function but I've never set aftertouch less than about .025" or rarely greater than .045". +/- .010" or the thickness of 3 sheets of paper is hardly something that 99% of the pianists would notice a difference on. The cloth/felt punching will compress this amount with just a few ounces more pressure.




Consider that the next time a customer asks you to stick some thumbtacks into the piano hammers or install some bargain basement pacific rim hammers on a fine grand. The results of our work follow our name and reputation. If you set an unusually wide aftertouch and then in the summer you can't feel that jack toe wiggle a touch with the key down (jammed)....do you think people will blame the pianist or the tech who set it. If the customer and pianist is one in the same, then they will likely inquire why you din't warn them of this possibility. To the same effect, I know of a few refinishers that would sooner drink hemlock or send the business elsewhere if someone asked to have their Steinway painted powder blue.



Never seen any proof of this anywhere. Haven't even heard a good theory on it but I'm all ears if you have one.

Anything that affects the touch, and thus the relation between the pianist and the piano, will affect the tone. Really, the person to ask how this plays out, is the pianist. And the pianist won't give an answer in technician lingo. Part of our job is to connect their experience with our technical and non-musical understanding of what's going on. The piano is first and foremost a musical instrument, a means of producing music, which of course is a highly subjective, personal, intuitive, and even emotional endeavor. If you're a musician, especially a pianist, then you have a headstart.

True enough Zeno, but one can also say "just vary the velocity of the hammer, you will vary the tone". Outside of pedalling and varying amplitude via the keys, there is nothing else pianists are doing to change the tone.

Now I am referring to conventional piano playing above. Chick Corea, Jonhn Cage, the Piano Guys and other experimental players will incorporate techniques and other objects to partially mute or manipulate the strings and soundboard for tonal changes.

In the same light, the music itself, its structure, chording, melody ect...will interact by way of resonance and harmonics to produce an overall tonal change but this again is completely different.

Excellent explanation of how working from reality trumps working from specs.

Zeno, perhaps this topic deserves its own thread title "What is tone?" since I have heard the word used quite loosely to mean a lot of different things for people over the years. Its definition is rather open to interpretation:

tone: noun The overall quality of a musical or vocal sound

Since we have other specific descriptions like amplitude, frequency ect... I generally consider "tone" as being the spectral envelope of all the frequencies heard. The descriptive attributes we asign to tone such as warm, shrill, bell like, deep, thin ect...all refer to the spectral envelope of the sound. (added) By "spectral envelope" I am not only talking about frequency content, but also the variations in amplitude amongst those frequencies.

In this regards, this spectral envelope changes from one thing only via the piano key, the amount of excitation force on the string. The same excitation force on the string will deliver the same spectral envelope each and every time. Since velocity of the hammer is the only thing that changes the excitation force, it is reasonable to assume that the pianist is in control of tone via the velocity they impart into the hammer via the key stroke. Velocity of the hammer cannot be controlled by the pianist after escapement. There can also be an arguement made that velocity of the hammer cannot be reduced by the pianist anywhere in the keystroke by human /mechanical connection..it is momentum dependant and will only reduce speed from the forces working against it (air, friction, gravity ect).

To put it in a nutshell. If I stipulated to pianists that they are free to play a note any way they want, but that hammer must be travelling at 2m/s at escapement, there is nothing they can do to alter the spectral envelope (tone) of that note which corelates to that hammer speed. If a pianist tells you different, be polite, smile, and then walk away knowing fully that it is a pile of hooey. It cannot be done.

I see this type of elaboration by many artists (not just pianists) to add more depth, meaning, importance and appreciation for what they do. Its good small talk. It paints pictures in peoples heads that arn't there in reality. There are many things with playing the piano that a good pianist can convey with technique and articulation, but mysteriously altering the tone of notes outside of the hammer velocity/amplitude connection is not one of them.

This is good discussion -- and this is largely my perspective as well. I would add just a couple of thoughts that "might" possibly modify the idea of the pianist just talking "arty nonsense" -- which certainly does happen.

1) Experimentation and research has demonstrated that action noise -- including primarily key impact -- does indeed enter into what is considered to be piano tone. In fact, recordings have been made where the key impact has been eliminated and the tone is not as "piano-like". This leads to two possible consequences:
a) by affecting when in the total sound envelope the impact noise happens, amount of aftertouch "may" affect perceived tone.
b) Having enough aftertouch can permit the pianist to more easily "play to the bottom" or "play off the bottom" of the keystroke which, because that affects the impact noise component of the total tonal envelope can give the pianist some control over the tone

2) It may have to do with the pianist's "follow through". As in golf, follow through may have a significant effect on how the athlete/pianist actually performs even though nothing more happens after the golf ball leaves the club head or the hammer flies free from the wippen. So, even though there is no "scientific" event in the realm of physics that is happening, it is affecting the ability of the pianist to perform.

I mention these two factors merely as qualifications to the basic statement that when discussing these issues pianists are, indeed capable of generating a "whole lot of hooey".

Keith, I was actually going to mention the analogy of "follow through" in my posting and am glad you bring it up. In reality it doesn't change what happens to a ball once it leaves a club (eg. golf). I had a semi pro golfer explain this for me and he said the follow through does 2 things. First, it prevents injury caused by trying to stop the club momentum to quickly or interrupting the natural body movements to abruptly. The other reason it helps is that if one gets careless, you could assume the ball contact was made and abandon the stroke form before the ball has left. It is a lightning fast process and its easy to make a judgement error.

I don't give the human touch/feedback/key manipulation arguement in regards to after touch a great deal of weight because these were not the reasons why we have it. Its a mechanical safety measure/solution, not an added tone control feature.
Even the arguement of the sound time delay coresponding with key bottoming is not a big issue for pianists to deal with. I have never heard anyone (myself included) mention this effect when playing a digital piano. The majority of DP's produce the sound when the key bottoms out and we seem to adjust to the couple milliseconds of delay for the sound from the speakers to reach out ear. I notice no difference in my playing on a DP if I'm wearing headphones as opposed to not wearing them. The difference is huge between the speed of sound in air as opposed to the speed of electricity through the headphone wires.

Emmery,

In short, many of my clients do feel the many differences of regulation, including after touch.

I find your comments about pianists shortsighted.

What is the expression? "You reap what you sew"?

There are many pianists that feel these differences strongly and of course many that are not so sensitive.

As I said, the most important relationship I have is with the pianist. They are hiring me and paying the bill ... not the piano.

Larry, I understand what your saying and my comments were related specifically to "after touch", not regulation in general or other things. I'm just as aware of the sensitivities we have for the feel, response and feedback we get from the keys as most pianists are, and play the piano quite well myself. Not all pianists agree about piano things either so it doesn't miff me to disagree with them on occasion. I too, listen to the pianist/customer. But I relate it to the limitations of what a piano can or cannot do. To this effect, I challenge you or anyone to prove that a pianist can change the tone of a note with any finger/ touch technique outside of varying the hammer velocity. (pedalling not allowed)
It simply can't be done. To assume that a change in after touch plays a role in tone alteration is just something more ridiculous...it occurs after escapement.


The next time a pianist beaks off about key dip or after touch, ask them to show you what they mean. You will find that the majority of them don't watch for or discern the point of escapement in the process. This alone, indicates they cannot tell the difference between a large key dip and a wide after touch setting or vice versa; an extremely common occurance amongst pianists.

Because of the work I do with pianos, I also realise there is a big advantage I have over most pianists, I understand the details of the mechanics, what they do, how they do it, and their limitations. This gap between a tech and a pianist should be bridged in an honest way. I'm reasonably adept at explaining things and find that customers are appreciative of that. I hate playing games, even if there is money to be made doing it.

My mechanic told me once that he will occasionally have a car owner come in and say something like, "I hear a squeal, I want you to change the wheel bearings". If the mechanic looks at the car and finds that it is the brakes that are gone instead, I think its part of his job to be honest and let the guy know. In fact, he should tell the customer it could be something else that causes a squeal before he even digs in. There are other mechanics that would just change the bearings and when the customer still complains about the squeal afterwards, they say, "you didn't ask me to fix the squeal, you told me to change the wheel bearings".

I had done some regulating and tuning for a concert pianist back a year ago who kept complaining that she hears a clicking sound using the sostenuto and damper pedals together but that it doesn't happen all the time. I chuckled to myself because I thought that any serious pianist knows about this little issue. I sat down and demonstrated what she was talking about and told her that its unavoidable. I even drew a little sketch showing why it happens and that its an unfortuante part of the design. She thought I was BS-ing her (I figure) and got a "tooner" in some time later to look after it. She got charged an hours worth of work, the piano still clikked, but the tooner assured her that it was no longer damaging the piano because of his "adjustments". Well, the thought of doing that never occured to me. I do like to feel good about myself when I sleep at night.

While it is folly for any pianist to assert they have more control over tone than pre-escapement velocity will provide, I do think you are selling pianists short here Emmery. They may not understand the mechanism the way 'we' do as experts, but they do know what they feel. If a pianist asserts that they are not getting the required amount of control or feedback from the piano, this may be associated with or dependent on the feel of the aftertouch. And regardless of the terms they may coach their complaints in, we know what the limitations are. But there is a massive psychological feedback mechanism going on when a sensitive pianist plays the piano, and it is our job to translate the (albeit often wild and grandiose) observations of a pianist into real and tangible adjustments that can be made to improve their piano playing ability.

And yes, it is important not to humour them too much when they make unsupportable claims about the tonal benefits of the way they want the action to be. But this is not comparable with your pedal clicking story - that's a simple mechanical shortcoming, handled with aplomb by a technician prepared to stretch the truth. But when a concert pianist complains he is not getting what he wants from the piano, it is our job to find out exactly what he means, and what changes we might affect that will improve the situation. To dismiss a pianist's complaints because he does not understand the limitations of the instrument is to fundamentally misunderstand his complaint - it's a rare pianist who actually wants something that is physically impossible, it's just ironic that it's a rare pianist who cannot describe what he wants without describing something that is physically impossible

Has anybody here ever taken an atheist to an art gallery?

What makes it hard to get ahold of this topic is that two things can be true, from one situation to another.

First of all, pianists can be thoroughly deluded about what is "really" happening. As an example, I recall a story Daddy told me about a situation where he was working with a pianist in a prominent summer music venue. She went on and on about some perceived failure of the piano. Finally, Daddy crawled under the piano, removed a keybed screw, came out and polished it and re-installed back in the keybed and then asked her to try the piano again. "Oh, wonderful! she said, " the piano is completely different!"

On the other hand, even though a pianist may not have the correct understanding of piano action mechanics -- or even of their own physical abilities -- they may well be describing something real. The element of keyboard noise which I mentioned has been verified -- even though no one really knows how to deal with that element. Pianists are capable of perceiving very subtle things and we can't just dismiss them out of hand, either.

Is it the piano or the pianist's brain? It could be either.

Everybody has a war story about the hoodwinked pianist. It's nothing to be proud of. I ask them to give me the context in which the problem arose.

Some pianists can create magic despite the natural limitations of a pianos action. Curiously, those who can do this never ask me for changes to the action. At this point, who cares what they believe???

To answer the original question, a dipblock is merely a template or gauge to ensure the same amount of travel of each white key. My own was cut from an old upright key. I think i originally made it for .390 at the front with a knife line in the keytop at the point it measured 3/8" which happened to be at the point above the guide pin. it has shrunk since then, so now, 30/40 years later, it has 2 narrow strips of tape on the bottom at front and back to create the dip and the angle the piano needs. Between the mail room and the office stock room and anybodys desk in between, all thicknesses of tape can be obtained. Such a simple tool can be adjusted for every situation once I have established what the dip should be in relationship to the rest of the action. Most often, the dip is the last dimension arrived at, rarely the first.

I always try to arrange it so that there are 2-3 of each color at the top of each stack of punchings so that one or two of a certain color can be unceremoniously ripped out or ceremoniously inserted in order to make further adjustments easier long after I'm gone. .