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A More Detailed Explanation of Regulation

In the FAQ's, we began the discussion of regulation with this response:

"Regulation is the general term that refers to any work that keeps the mechanism, (or action), working properly. When a key is played, a felt hammer strikes the strings. This is accomplished through a complex assembly of levers and springs which can be adjusted with extraordinary subtlety.

"When working at it's best, the piano can achieve an enormous degree of responsiveness. When properly adjusted, the key only travels down a small distance, (approximately 3/8"). While that small motion occurs under your fingers, a lot is happening inside that enables the instrument to be played tenderly and expressively, or with power and passion; with either lightning speed or smooth "legato." A well trained tuner is more than a tuner, he or she is a piano "technician" with extensive training in the skills needed to achieve and maintain the correct functioning of the piano mechanism and pedal systems."

The purpose of this article is to provide a basic understanding of how the moving parts work together to enable the player to perform with so much expression and dynamics, because regulation is the key to control. Once again, a truly comprehensive discussion of the complexities involved as each part interacts with the others would exceed the scope of this article, (and no doubt the patience of most readers!).

The challenge is compounded by the fact that some things that are easy to demonstrate are much harder to explain. Nevertheless, it is extremely important for the pianist to have a fundamental understanding of what happens inside the piano, both to facilitate good communication with the technician, and to help understand the limitations and possibilities of the instrument.

First, it should be mentioned that the action in both grand and vertical pianos is removable, to facilitate maintenance and repairs. The keys are simple levers and are also easily removed. In general, the action design found in grand pianos is considered to be more responsive and "faster" than the vertical action, and larger verticals are considered better than smaller ones. However, the same fundamental relationships exist in all pianos, and can be presented in a general way.

So, since regulation refers to ANY work involving the mechanism, let's beak it down into three areas:

  1. Friction and key weight
  2. The moving parts and how they work
  3. Piano pedals

Part I: Friction and Key Weight

Obviously, when a piano key is played things MOVE, and whenever things move we have to contend with friction. No matter how perfectly adjusted the moving parts are, if they are too loose or too tight, the mechanism cannot possibly function properly.

There are many points in each note where friction can occur. Basically, there are "rubbing" parts and "rotating" parts. Everything that moves inside the piano involves felt, which is a specially processed wool. Some felt is firm and reinforced for strength, other felt is soft and "cushiony." Let's start with:

The Piano Key

The key is a simple lever with a round hole at the bottom, near the middle. (This fits over a pin that acts like a fulcrum while the key goes up and down like a see-saw). If this hole is too loose the key will be noisy, and feel "wobbly" under your fingers. An enlarged balance rail pin hole can allow the key to travel forward and backward, making it difficult to keep the key fronts in line.

It the pin hole is too tight the key will feel heavy and "resistant." Carefully fitting the key to the balance pin is a critical first step.

Above this pin hole at the middle and top of the key, the key is slotted and lined with felt on both sides (the center, or balance rail key bushings). This allows the key to "see-saw" in a smooth, supported manner.

At the front underside of the key there is another guide pin, and the key has another felt lined slot (the front rail key bushing). As the key travels up and down this front rail pin keeps the key from wondering from side to side.

Before anything else is done, it is critical that the key itself is properly fit at these friction points. Tight keys can lead to a heavy and "sluggish" response, and poor repetition. If the key is too tight it will not return to rest position, and is the most common reason for "sticky keys." A qualified technician will have the tools necessary to properly ease and fit the keys.

Action Centers

The key is "connected" to the hammer through a series of parts. Many of these parts rotate via two wooden pieces that are "hinged" together.

These "hinged" parts are connected to each other with a small metal pin. The pin is fit tightly into one of the components. The other component supports the pin on both sides in a hole that is lined with felt (called a felt "bushing"). This felt is adjusted so that the pin is held firmly, otherwise the rotating part will be loose and "wobbly." However, if this bushing is too tight the motion will have excessive resistance.

On a grand piano there are four such joints, or "action centers," in every key, and more in the damper system. If any of these felt bushings becomes too tight, the note will not perform properly. As with the key, excessive friction at any of these action centers will make the key feel heavier, and slower to return to rest position. It will also make it more difficult to play expressively, and inhibit proper repetition.

Again, a qualified technician should be able to locate which, if any, of these action centers is too tight. There are good lubricants that can be applied to the felt that can often correct the problem quickly and inexpensively.

However, sometimes the tight action centers do not respond to lubricants. In this case the parts must be disassembled and "re-pinned." This is a time consuming job that requires skill and experience.

[Aside: Although it is generally agreed that Steinway pianos are some of the greatest instruments ever built, there is a problem specific to Steinway grands built in the 1920#&39;s and 1930#&39;s. The wooden parts were treated with a paraffin oil wood preservative. However, over time this caused a chemical reaction with the alloys in the center pins, creating a bluish-green residue. This gooey residue causes the action centers to essentially "freeze," resulting in very sticky keys and an action that is virtually unplayable.

The only solution to this problem is to replace the parts. This should only be done by an experienced technician, because replacing these parts is an integral part of a full action rebuilding, and normally includes new hammers and other new parts.

The good news is that these are such great pianos that after this work is done most still sound wonderful, and can be returned to years of service, at substantially less cost than replacing the entire instrument.]

Key Weight

There are a few other areas where friction must be corrected, however, the keys and action centers are the major sources. Once the issues of friction have been addressed we can begin to analyze the key weight, often called the "touch weight."

Many people talk about how the action "feels." This is a complicated perception, and only partly related to the weight, or resistance, of the key. The adjustment of the moving parts is critical to the responsiveness of the mechanism, but does not directly impact the resistance of each key, so key weight is the next issue we should consider.

How Is Key Weight Measured?

The amount of force it takes to press the key down is called the touch weight, or "down weight" (DW). We measure this is grams. A professional technician should carry a set of graduated weights. We can place a weight on the key. If the key does not move, we add weight until we determine how many grams it takes to start the key moving downward.

There is no absolute industry standard for this. Generally, the DW will be a few grams heavier in the bass section and gradually get lighter to the top end. A "good" average example of the DW would be around 50 grams in the bass, 48g in the tenor (mid range) and 46g. In the high treble.

Measurements can typically vary as by as much as 2 grams from one key to the next, so it is important to measure enough keys to get a representative average. The ideal DW is subjective; some artists prefer a heavier touch, some a lighter. Still, it is important that the piano does not stray too far from these "ideals."

For example, a DW of between 46g. and 56g. in the tenor may be acceptable, as long as the friction is correct and the player is not unhappy. Higher or lower than this range and we can assume that something may be wrong. It is important that your piano is not too different from others, as pianists are often required to play instruments other than their own.

It may be desirable for beginning players to have a lighter than average action. However, if it is too light they will not develop the strength necessary to control the touch on other pianos they are likely to play.

Similarly, a heavier than average action can help the pianist develop strength, and prepare them for more challenging pianos, as a baseball player may swing a heavier bat before stepping to the plate. Still, an action that is too heavy can cause physical injury and should be fixed.

How Is Key Weight Established

Just like on a see-saw, if we are sitting on one end and our friend slides forward or backward on their end, it will be easier or harder to lift them. This is simple leverage.

The key is a lever, acting like a see-saw with your finger on one end and the action parts on the other. The precise location of these parts determines how their weight will be felt at the front of the key.

Once this has been set by the manufacturer, the DW is measured and lead plugs are set into the key to make the front end heavier, until the desired resistance is achieved. If the piano has its original parts and the friction is correct, the DW should be that which was set by the manufacturer.

If your piano has its original parts and the friction is correct and the DW is still too high or low, it has probably been improperly weighted. Lead plugs can be added or removed by a qualified technician to improve this problem. It is generally easier to make the action heavier than lighter. Whenever you add more weight to the front of the key you slow down the key return. Careful measurements must be taken to determine how much weight can be added before one problem is created in solving another.

On many grand actions there is a spring that helps reduce the weight of the action parts. When done carefully, the tension on this spring can be adjusted to make changes in the DW. When a grand action is being rebuilt it is often possible to replace a standard part with a spring assisted one.

However, whenever an action is fully or partially rebuilt it can dramatically affect the DW. For example, on average, if a new hammer is one gram heavier than the one it replaces, the leverage of the action will result in the DW increasing by around 5 grams!

For this reason it is critical to measure the DW before a job is begun, and carefully check it as part of the process involved in replacing parts, especially when replacing the hammers.

Recent Innovations

There have been a number of significant and revolutionary innovations in the area of touch weight in recent years, most notable the introduction of David Stanwood#&39;s patented "TouchDesign" system. For more information on this fascinating procedure, you can find a link to his web site in our Links page.

Mr. Stanwood began by totally rethinking the inconsistencies of part weights, ratios, and leverage, and developed a technique for redesigning any grand action in a way that dramatically improves the evenness and fluidity of the touch.

He has also recently perfected a method for making the location of the key fulcrum adjustable, allowing the trained technician to customize the action to meet the needs of the most demanding and professional players. These techniques can be used when rebuilding high quality pianos that are ready for an overhaul, or to improve even the high end newer instruments as a sophisticated "upgrade."

Also, the use of magnets as a substitute for lead weights has been introduced with excellent results. When lead in the keys is reduced or eliminated, it removes the affects that the extra mass invariably introduces into the key motion. The magnets are adjustable so that the desired resistance can be easily altered to meet the artist's changing needs.

Part II: The Moving Parts And How They Work

This portion of the article is intended to provide a basic introduction to the most fundamental steps involved in grand action regulation, with a general description of the effects these adjustments have on the "feel" of the keys, and how each adjustment affects the other.

My objective here is to introduce the reader to some of the elements involved in the adjustment of the piano action. Each key can be individually adjusted in dozens of places, and each adjustment has an affect on the total feel and performance of the keyboard.

Hopefully, a greater understanding of the types of adjustments that can be made will help the pianist to better communicate with his or her technician, and increase their appreciation for what can and can#&39;t be done.

I will be focusing on the grand piano action; the vertical action has fewer adjustments, but most of the principles are the same.

We always begin at the key. After all, this is the only part that most players see, and however different things are "behind the scenes," the key must provide a similar if not identical experience from piano to piano. Therefore we have a few simple rules.

Key Height and Key level

First, the keys must be all be at the same level, squared (that is, not tilted left or right), and evenly spaced. A consistent keyboard is the foundation to all other adjustments.

The Key Dip

Next we set the distance the key travels downward, the key "dip." The key travels down until it is stopped by contact with this a thick felt washer. By adding or removing thin paper washers from under this punching we can set each key to dip approximately 13/16".

Correct key dip is essential to a good "feel." As the key moves down, a lot of other functions have to take place deeper within the action. If the dip is shallow these functions will be compromised. Playing a piano where the dip is excessive however is tiring and inefficient, and can make the keys feel heavier.


Assuming that the key dip is correct, aftertouch refers to the distance that the key travels downwards after all the moving parts deeper in the action have finished, and before the key reaches the felt "stopper." There does not have to be a lot, but if there is no aftertouch the action will feel heavy and difficult to control. Excessive aftertouch reduces power and indicates improper adjustments elsewhere in the action.

Action "Spec#&39;s"

The specifications, or spec#&39;s, for the keys, especially the dip, are critical and do not allow much room for opinion or professional differences. From this point forward, however, most of the remaining adjustments are interrelated, and can be somewhat subjective. Let me explain.

If one were to get hold of a technical manual, you might find a list of measurements indicating the "correct" resting positions and distances between various internal parts. The assumption is that if all parts are in these positions, the action will function properly. This is rarely true "in the field." Each mechanism is different, and has experienced different amount of wear. Unless the technician understands the affect each adjustment has on the other, adjusting the action according to "the spec#&39;s" will not necessarily yield the best results.

Also, each player is different, and many adjustments can be changed to meet these different needs. A player who desires absolute control on very quiet play will need a different regulation than one who desires lightning fast repetition.

Let#&39;s develop this by discussing how the resting position of the hammers is best determined.

Let-Off and Hammer Rest Position

When a key is pressed a hammer immediately begins moving towards the strings. If you press slowly you can make the hammer go up and down in unison with your finger. In the early part of the key motion, the player is "connected" with the hammer, imparting velocity as the key is hit.

However, at a certain point this connection must end. Otherwise the hammer will simply be jammed up against the strings as long as the key is held down. There is an adjustment which allows the hammer to be disengaged from the key referred to as the "let-off," or escapement. The closer the hammer gets to the string before disengaging the more control the pianist has, especially in soft play.

However, if it gets too close other problems can occur. Rather than setting this adjustment at some predetermined "specification," a skilled technician can play the key and adjust the let-off at the same time, judging by the "feel" exactly when the hammer is as close as possible.

Once that is set, and the key dip is correct, we can adjust the resting position of the hammers. If they start too far from the strings there will not be any aftertouch, and if they are too close there will be diminished power. In other words, a skilled technician does not start by setting the hammer distance at a predetermined height. Rather, by understanding the relationship between key dip, let-off, and hammer rest position, and by understanding the purpose of each function the optimum positions can be found.

The Rest of the Story

The key motion is imparted to the hammer via an "L" shaped wooden part known as the jack. The position of the jack at rest is adjustable, and critical to achieving the desired touch. After the hammer escapement, there is an adjustment referred to as the "drop" that is important in achieving efficient repetition and control.

When the hammer hits the strings hard enough to bounce off, there is a part that "catches" the hammer and stabilizes it in preparation for the next blow. Proper setting of this "back- check" is essential. Then, when the finger releases the key and the back-check "lets go," there is a spring assisted part whose job it is to stop gravity from pulling the hammer down. Instead, the hammer is boosted upwards, allowing the jack to get back into its starting position so that the key can be played again. Once again, correct adjustment of this spring is fundamental to a good feel and proper control.

There are of course still more adjustments that can be made. However, the summary provided should help the pianist gain an introduction to the marvelous complexity and subtlety of this extraordinary keyboard mechanism.

Part III: Piano Pedals

Finally, when discussing the proper functioning of the piano action you must include an understanding of the pedals; what they are supposed to do, and how they assist in creating such evocative and dynamic music.

Most pianos have three pedals. However, only the right pedal is uniformly used for the same purpose. The left and middle pedals can do different things on different pianos, although there is a general acceptance of their function on most instruments.


The Right Pedal

On grand pianos as on verticals, the right pedal is called the Sustaining pedal. When a vibrating string is touched, it will stop vibrating. However even if a string is not being played, it will tend to vibrate and "hum along" with other strings when they are played. When this happens the piano starts to sound muddy and the music loses its definition.

For this reason, when a note is at rest, a piece of soft felt is resting on that notes strings. When the key is played the felt damper is lifted off, allowing the strings to vibrate until the finger is lifted and the key returns to rest position. When that occurs the damper felt is once again pressed against the strings, making the note stop.

When music is being played on a piano, many of the notes fit together into a harmony structure and blend well together as they are being played. If the sustaining pedal is pressed, all of the dampers are lifted from all of the strings. This allows the player to blend all the notes until the harmony changes. When the same piece is played without the sustaining pedal the music sounds choppy and disjointed. The sustaining pedal is absolutely critical and fundamental to the creation of music on the piano.

The Left Pedal

On some inexpensive models the left pedal is employed just like a sustaining pedal, only for the low notes exclusively. Also, on rare older models the left pedal acted to move the hammers closer to the strings for improved soft play control.

However, on the vast majority of modern grand pianos, the left pedal is the "Una Corda" pedal. As discussed elsewhere, the number of strings per note varies from the bass to the treble. Early piano builders found that by having one big string per note in the low bass, two strings per note in the higher bass and lower tenor notes, and then three per note up to the top treble was the best way to achieve balance, power, and resistance to strings breaking under the force of the hammer strike.

As the piano is used the hammers develop depressions at the tip of the striking surface that gets packed down and harder than the felt on either side of these marks. By shifting the entire keyboard towards the right side, the una corda pedal allows the pianist to control what part of the hammer tip hit#&39;s the strings, even to the point of missing one string entirely. (Una corda is Italian for "one string.")

This can assist the player in producing a range of subtle but expressive effects, as the tone is changed to become more ethereal or delicate.

The Middle Pedal

On most grand pianos the middle pedal is called the "Sostenuto" pedal. If a pianist plays a note or group of notes and engages the Sostenuto pedal while these notes are still being held down, the pedal will act as a sustaining pedal for only those notes after the fingers are lifted. In other words, you can play a note or notes and allow then to sustain while subsequent notes played are dampened as usual when the finger is lifted.

This pedal was originally included on early piano to allow the popular organ music of the day to be played on this "new#&39; instrument. After all, the first piano builders had no way of being sure that anyone would want this new instrument on which they had invested thousands of hours and so much money. Since so much keyboard music existed for organ in the early 1700#&39;s, this pedal allowed the piano to simulate the function of the organs foot pedals,, which when held down could sustain a note indefinitely.

As it turned out, of course, the piano was wildly popular on its own and eventually became the worlds dominant keyboard instrument. As more and more composers wrote piano music the Sostenuto pedal was rarely needed or used. Today, many people have no idea what this pedal does.

However, that is too bad, because the musical effect when this pedal is used properly can be quite beautiful. Debussy and other romantic and impressionist composers found many ways to use this pedal, with dramatic effects.

If you have a grand piano, try this. Play a note and hold the key down. Next, press the middle pedal and hold it down. Then, release the key while keeping the pedal pressed. The note should still be sounding. Now, play some other notes. They will start and stop as you press and lift you fingers, but your first note should still be sounding. If this happens, your piano has a properly functioning Sostenuto pedal.


On vertical, or upright pianos, the right pedal functions the same way as on grands. It is a sustaining pedal which when pressed lifts all the dampers off the strings and allows the notes to blend together.

However, grand pianos were invented before uprights. The need to build a piano that took up less space in a room became evident in the 1800#&39;s, and piano makers endeavored to recreate the grand piano in a model that could stand against a wall.

This required significant changes in the action mechanism. The result was quite acceptable, although this new design did compromise some of the actions subtlety.

However, it was not possible to duplicate the una corda function, and the Sostenuto, though doable, was expensive and difficult. Further, since the Sostenuto function was so rarely used it was not cost effective to duplicate this on most uprights. A few modern uprights do have a middle pedal that functions exactly like a grand Sostenuto pedal.

On most modern uprights the left pedal works by shifting the hammer resting position closer to the strings. This shortens to ‘swing" of the hammer and assists the player in soft play control. Most of the time this affect is subtle. If you have a vertical piano, you will notice that when the key is at rest and you press it gently you feel the weight of the hammer immediately.

However, if you then press the left pedal and try another key you may notice that now the initial resistance of the key is less, and in fact the key does not begin to move the hammer until it is a about 1/8" down. Thus, you have essentially shortened the key travel and thus you have shorter "swing." When you are trying to play quietly, pressing the left pedal will help.

As for the middle pedal on vertical pianos, on many early uprights this pedal did nothing at all. Clearly the Sostenuto function was not essential to the pianos, and it would have been easier to just leave the middle pedal out and have only two pedal. In fact, many early models had only two pedals. However, piano dealers soon found that the public expected pianos to have three pedals and assumed that a piano with only two must be inferior.

As a result, manufacturers often added a middle pedal with just a spring under it so that it could go up and down. Other times it was connected to the left pedal so that you could use either to shift the hammer rest.

Ultimately it was more or less universally agreed that the best user for this pedal would be as a "mute" pedal. A rail with a felt strip was suspended above the hammers. When the middle pedal wa engaged the felt would drop down and rest between the hammers and the strings, creating a very muted and quiet tone. This is very useful for toning down the rather loud piano while doing scales and exercises, or when playing late at night.

Most modern vertical pianos now have a middle pedal mute function.

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