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Mark,

I watched your video blog #3 and video demonstration

http://www.youtube.com/watch?v=P7NFEFBaVvY

It was a great analogy and I have learned from it. I would appreciate if you could put me right on one issue which is:

I understand that the string must slide over the vee bar for these to be any change in pitch. If this change is made with only a "wind-up" (my words) of the pin and not a foot change surely the string will slide back over the vee bar and therefore just return to its original frequency when the pin "unwinds"? How then can the string be tuned if the pin foot has not been moved?

Ian

That is a good question. There is a bit of leeway with the pin/block couple. My goal is to have a similar "orientation" of each pin, but if you take in account the different NSL length this may be untrue. So it may be a similar ratio of tension between capo friction and pin/block resiliency,

If I read you correctly I should be considering it as a differential friction between a tightening and slackening because of the directional friction on the pin? Also as you say the effect is dependent on the NFL but not applicable to me as I only will be tuning my own piano.

So more and more I am appreciating the original advice I received here which is that stability should be my principle goal.

thanks,

Ian

The resiliency available within the couple pin/pinblock is what balance the tension in the NSL. (so the friction still get the sounding length in tune) The audible part (speaking length) is by-product of that "knot".

There is no reason you could not work the pin from its bottom but yes it may be too early. The pin is a sort of auto locking device that is stopped when submitted to the wire tension while being in a slight disequilibrium itself (tending to go sharp).

That said, playing a lot the note and not trying to turn the pin immediately will help you to feel the moment where the bottom of the pin is disrupted from its locked position.
it is better to untwist and break it before tuning if the pin is not in its best posture, but if it is I look for the minimal motion without changing the pin orientation, I tense, move all and release an from pin an nsl point of view, nothinh have changed.

The "knot" install between those 2 opposite forces. That is also why we need more tension in the upper part of wire, it help by providing the energy to put the pin under stress actively.
Strong blows should only make the fit tighter/stronger, as do small wiggling of the lever. The dynamic and energetic part of the tuning process begin at that level, that is not as easy as searching for a given frequency, but the physical coupling helps, and can be noticed.

Best regards.

Yes I agree with the term "directional frction" the pin is a transmission. We put it in position and it brake by itself.

The reason why the pin foot does not have to be changed in oder the change the pitch, and be stable, is that there is friction at the v-bar. In basic terms, if the friction at the v-bar is greater than the tension difference between the SL and NSL then the string will be delayed moving across the v-bar.

Actual fine tuning is accomplished by taking advantage of this fact in oder to both finely change pitch, and to change or restore the tension difference while not changing the pitch.

yes but ideally the fine tuning takes its location at the foot of the pin. My tuning pin have more or les one optimal posture, if I need to tweak a little the tone, I will move the foot of the pin .
The goal is to obtain a similar stress in each pin

And not one with 1° twist, the next 2° etc.

The amount of small modification allowed depends of the tightness of the pin, but in any case it is better not to cheat on the pin/NSL ratio.

Sorry for the late response, Beemer. Chris and Isaac are good teachers and have pointed you in the right direction.

My goal is to explain my techniques in as consistent and easy to understand terms as possible. Not so easy to do, as these are advanced techniques that I am trying to present to beginners because I strongly believe that beginners should learn advanced techniques if possible, so they get a better chance at precision early on, and don't have to unlearn basic techniques in order to relearn more advanced techniques. I've seen some confirmation with my own students that this works.

With that in mind, I have since defined a few terms that were missing from that video. That was actually my first lesson video, the first two videos were more just me talking about my teaching methods.

This stuff is about ready to be posted in another video that describes the friction and elastic deformation in the piano pin/string system better.

So, with that in mind, here are a few more terms that I have defined that help answer your question, and hopefully explain when and how you can get stability without moving the foot.

Tension Differential (TD) = Non Speaking Length (NSL) Tension - Speaking Length (SL) Tension

This is a good number to think about because, if it is positive, it means the pitch wants to go sharp, i.e. the string wants to slip across the v-bar in a sharpening direction, toward the NSL; NSL Tension > SL Tension.

The opposite situation, NSL Tension < SL Tension, means NSL is "flabby" and the pitch wants to go flat.

Because of friction at the v-bar, there is a range of TD that will not result in slippage. Think of a stone on a book. There is a range of angles you can orient the book, where it will not move. I call this range the Tension Band (TB).

So, if the TD < TB, no slippage.

What's more, there are two Tension Bands, the Static Tension Band (Static TB), and the Dynamic Tension Band, (Dynamic TB). After tuning a note, the Static TB is in effect. During hard blows, the Dynamic TB is in effect, and the Dynamic TB is narrower than the Static TB. That's why a note can be stable when sitting there all by itself, but slips when played hard; the TB narrows.

Think of the stone on the book. There is range of angles where the stone doesn't move, but if you tap the book once, the stone will begin sliding, and not stop until it falls off the book. (In Physics, we say the Dynamic Coefficient of Friction is less than the Static Coefficient of Friction. Or, perhaps more easily imagined, Dynamic Friction is less than Static Friction.)

So, how can a note be tuned without moving the foot, and still be stable? Easy. When it wasn't stable to begin with. Also, as long as you leave the NSL Tension within the Dynamic Tension Band.

This is common in the "sharpen, then flatten" technique.

Consider a flat note. You pull it sharp a bit, then flatten it a bit. If you do everything right, you get stability, and often, without foot movement on the flattening motion.

During sharpening, TD goes positive, keeps going positive until slippage, then stays at a constant positive value (if using slow pull) until you stop. When you stop, the pitch may be left slightly sharp (not always), then you must reverse the hammer force, and flatten it a bit.


As an aside, let's consider a 12:00 hammer angle, i.e. only untwisting affects NSL Tension. (Unbending is perpendicular to the string, so no effect on NSL Tension.)

During sharpening, the NSL Tension is right near or at the top of the Tension Band, (Static, I believe) pulling the Tension Band up, and the pitch with it.

During what I call After Tuning, the untwisting serves to reduce the NSL Tension slightly so it is just below the upper limit of the Static Tension Band, but may still be above the lower limit of the Dynamic Tension Band. (Now you know why I need a video to describe this!)

It is possible, because I've experienced it, that the NSL Tension can be left above the Dynamic Tension Band. So when hit hard, the pitch goes sharp.


But let's imagine that the drop was sufficient to leave the NSL Tension quite low in the Tension Band. I.e. stable on its own, but ready to go flat on a hard blow. (NSL Tension is above the lower limit of the Static Tension Band, but below the lower limit of the Dynamic Tension Band. I.E. unstable; ready to go flat during a hard hit, which temporarily induces the narrowing of the Static Band to the Dynamic Band.) I apologize. I'm getting dizzy just writing this. I hope you are still with me. If not, just reread it a few times. It'll start making sense.

You might try a couple of hard hits. That might drop the pitch. But one technique that a lot of people use is what I like to call massaging the pin down.

You apply a gentle force to the hammer in the flattening direction. One tech recently described it as "breathing" on the pin. If the NSL tension is close to the lower limit of the Static Tension Band, the massage just might cause the NSL Tension to drop below the Static Tension Band limit, and cause the string to slip across the v-bar, thereby producing a flattening that makes the pitch closer to where you want it. (Remember, we left it sharp.)

What's more, the "unmassage" or After Tuning as I like to call it, springs the pin back up to where it was. Since a flattening of the pitch is equivalent to a lowering of the Tension Band as a unit, the return of the NSL tension to where it was before, leaves it more centred within the Tension Band.

And remember I said NSL Tension may have been within the Static, but not Dynamic Band? Well now that the whole band has lowered a bit, NSL has a better chance of being within the narrower Dynamic Tension Band.

Tuning this way requires a sensitivity to imagine these values and their relationship to each other. It is their relationships to each other, and not their absolute values, that help me to visualize what is happening.

It is the achievement of stability using this visualization technique, that confirms to me that my analysis is close to what is actually going on, and has given me the confidence to "step into the ring" and share my method.

I'm still working on the video that has more visual tools to describe the method.

Questions welcomed and appreciated. It helps me to produce a clearer lesson.

I hope to write a book called "The First and Last Tuning Technique You Will Ever Learn".

That technique is, of course, Stability. Because of the need for our stability to be within our level of precision, after our precision improves, we need to keep refining our stability technique to match our tuning precision; the first and last technique you'll ever learn.

Learn stability; learn precision. Improve precision; improve stability.

Mark,

In my engineering studies (mainly electronic and motion control systems) the word that comes to my mind for the situation of discussing pin directional friction is "stiction". Is that a word also used in the US?

Ian

A quick search on the term lead me to "surface micromatching"

It may explain how old and used pind (less thread remain than originally) can still grip well when properly positionned.
(on old pianos I use the strings force even more, to have the pin stable, and it works - tuning to pitch being better than to 435 Hz then)

I was/am under the impression that the slow pull motion allow to orient better the wood fiber in the hole, so their direction add to the friction. But sure the perfect maching between surfaces (that are sort of "machined" when slowly pulling) Is certainly a good part of it.

There is always a part of the pin's hole in the block that is reserved for final friction. it is in the front of course on about 45°. That surface I always protect as much as I can when tuning.

ALso when we are untwisting the pin, we push on that, and it may reinforce the matching between surfaces.

In any case my feel is that slow pull optimize the bottom friction of the pin, allowing to use it as the beginning of the braking surface. It is also of course tactile as it allow to keep a close contact with the whole pin.

Tuning many old pianos one learn to be aware of that. Then with modern recent ones the bottom resiliency is very high and allows a large leeway. It is even difficult sometime to know how the end of the tuning pin is acting, but as it is tight, we can tune adressing mostly the upper half (or2/3) in the block.

Regards

Learning to feel the difference between "locked" and "unlocked" pin is an important point in tuning.

Can someone compute the amount of torque transmitted to the bottom of the pin, due to the lateral position of the string ?

I could compute the amount of force but at the point the string applies.

See correction below:

I am not concerned with the friction between the pin and block and whether it produces elastic deformation of that system. I do not believe, or have not experienced success in trying to use that as a tuning aid.

The pin friction does, however, affect the degree of elastic deformation of the pin itself during tuning, and hence, After Tuning. That does affect NSL tension considerably during After Tuning.

Isaac,

You would need to consider Young's Modulus of Elasticity. I am not familiar with how it is used in formulas. I tried once, but it is not intuitive.

What is perceived in the tuning lever is not only due to the pin, or the string. A good block have enough resilience to counter act the one of the pin, they both react to the force coming from the wire.

here I come from a somewhat free setting to a strong one, just wiggling does the job, (for the ones that do not like to do all in twisting/untwisting motions) but the initial posture of the pin is what allows it .

[video:youtube]M8gleqh7nvQ[/video]

Nice.

Listen to my video on beats. (I think you have, eh?)

In the middle, I have two computer generated tones at 440Hz. I had thought two tones at 440 would produce a louder 440. I was confused to find that sometimes the volume was less; when the peaks of one tone lined up with the valleys of the second tone. Both at 440, exactly. But the tone was sucked away from the note. Just like your second note. Out of phase.

When tuning unisons to be dead on, you risk the "sucking". A slight bloom means you will never have the "sucking". Plus of course the projection and sustain are better.

I like it. Videos are so much more easy to explain a concept.

Isaac,

I see you obviously have a heightened sense of elastic deformation and friction in the pin/string system. You will have a lot to say when I am finished my stability video.

I still do not consider what you are doing as having much to do with the elastic deformation of the pin block. (Maybe I am misunderstanding. Like I said before, we may be talking about the exact same thing.)

What I see you doing is playing with the string slippage across the v-bar. Each time leaving the NSL tension higher or lower within the tension band, the pin always going back to its original position.

I am willing to concede the possibility that, over time, a pin left "high" in the hole, may settle. All the more reason for leaving NSL tension high in the Tension Band.

(Actually, after rewatching the video a few times, I think that is exactly what you are doing! You can raise easily but must really bend to lower. That's because the NSL tension is high in the tension band, closer to the upper limit, farther from the lower limit. Good stuff!)

Hello Mark , thank you for the comments, yes I agree totally with the NSL higher force.
(I globally agree with your sedcription of the process)

Sorry that will be usually long

The wire moves on the bearing points (a lot on an upright piano) until there is enough force to get to the equilibrium of forces.
Then the only mean to really be sure of the balance (due to the pin's posture) is to push and pull on the lever.

Experienced and tuners in a hurry will use wiggle and can leave the pin in a half stressed position, that will harden with a test blow or when the piano will play..

It also can be attained more directly just with slow pull untwisting motion, but it is dangerous to avoid checking.

I was not so much aware of the elasticity of the block, but when testing pin deformation and twist in a vice, there is visibly more available in the piano.
(That also mean that we are directly interacting with the steel wire elasticity)

I suggest that leaving the pin "high" (or "loaded") allows it to lock as when you are turning a screw in the wrong thread, or as it happen with the key cover of a grand if you do not pull straight.
The pin install itself out of its rotational axis somehow .
plus its little twisting that create a real strong brake, and possibly the pin is allowed to grip in a larger (ovalized) hole, that way.

We usually learn to untwist and press the tuning pin a little on the block (then use a hard blow) ,but what makes it efficient is :

To avoid any significant lowering (get there in one shot, avoid turning the pin counter clock wise)

To have a good tension reserve for the NSL, so the pin can be left in its extreme deformation position, that should correspond to the NSL force -160 Newton +- not nothing.

In the video I said the "knot" opens between the pin and the wire, that is not really exact, the knot stay put, but the tension goes down in the NSL and speaking lenght. That is the amount of give left to the pin/block that is evaluated that way.

If when pushing pulling, the ratio Up Down is the wanted 2/3 1/3 it will remain the same until the pin is tighter.

So a lighter setting with the correct ratio IS yet the so called "knot" (why I said the knot opens)

With old blocks the job is asking more of the pin and wire, so it is less easy, the block resiliency is small or located farther of the immediate wood around the pin. Still once installed the balance of forces seem to stay put for years.

At the moment we get the exact ratio up/down we can push the pin to be tighter and tighter. In final it stay in place because the string is pulling on the pin. I was surprised to obtain a similar setting with very old square pins, without thread and a very short portion in the pin block (they where in iron too).

Yes Videos are good to explain what happens.

Of course it is always possible to obtain a good setting with other means, as long as the pin is allowed to freely fall in its good location. What I consider unavoidable is the testing of the NSL in regard of pin's tightness.

While raising, once the pin is torqued it will tend to lock by itself when the pressure is released, and stop in a tight position. the slow motion at the beginning of the move toward high is what give us the control. I did not use the impact levers but they may be efficient if the slow pull is used prior to the move, I guess.

The smallest and most controlled motions are obtained with tension plus wiggling, with some control on the braking of the pin in the hole obtained with lateral pressure, so the tick of the bottom of the pin is a springy motion, better perceived.

Doing so from an original good tension ratio (good pin setting) leave the pin in the same exact posture it was, speeding a lot the tuning process if that have been installed at some point (could be precedent tunings)

One of my pianos was tuned by a colleague recently. after 16 months +- he needed 30 minutes to do a very good job.

Best regards.

Videos are a good way to discuss ,way better than explanations.

BTW my first unison have some too fast meaowing probably due to hammer mating. I usually avoid that, but the spectra is the one of the "smiley".

The slow pull is giving more control as the high tension wire is more reactive and have less friction.

A good part of the job is done with the double stroke, to be sure to keep the wire free (one strong and one soft). Not necessary for all pianos, here I was more doing so for security because of the video.

Test blows are often more useful during tuning (than at the end) if necessary.