Wood vs. Composite
100 years ago golf clubs, tennis rackets, airplanes, and action parts were all made out of wood.
Fast forward to today and you’ll find that only piano actions are still made from wood.
Over the past century, hundreds of thousands of innovations and technological breakthroughs have been discovered or accomplished, yet piano actions are still made the same way they were in the early 1900’s.
Why?
For reasons unknown, the large majority of action companies have chosen not to take advantage of or simply ignore advances in design and materials and have preferred not to stray from the last century’s cutting edge material—wood.
An instrument of precision
A piano action is an intricate series of small machines that build upon each other—if something is wrong or off with one component the problem will quickly escalate and affect the entire note. It goes without saying then, that to build a dependable, responsive action that will stand the test of time, it is essential to use a material that is both extremely durable and reliable.
Unreleased tension
Wood is a “tension material”, which means that it has stored up tension inside it. Over time, this tension is released and wood will twist and change from the original shape that it was cut to. In a piano action, every component that is made from wood is susceptible to this, however, the parts that are affected the most are the jacks and hammer shanks.
A jack is delicately aligned in the repetition window with tight tolerances. When the tension inside the jack is released it is very easy for it to lose its position in the repetition window and make contact with the balancier. This contact creates friction, and as a result, the note won’t play.
For shanks, the released tension generally causes their attached hammers to shift to the left or right. Not only does this shift disturb the string alignment (which changes the tone of the note), but it often causes the attached hammer to make contact with other hammers, causing the note to malfunction or to even not play at all.
The timeframe for when wood releases its tension is completely unknown, though humidity does accelerate the process. It could be one year or it could be ten—since wood is an organic material it is impossible to predict. Regardless, when it happens, an action regulation becomes necessary, increasing the maintenance cost of the piano.
Humidity and the flange screw
Wood is a hygroscopic material, which means that it absorbs moisture very easily. During the summer the humidity in the air (moisture) rises and gets absorbed into wooden actions. This causes them to expand. In the winter, the opposite happens—as the humidity is reduced, the wood dries and shrinks. This cycle of expansion and contraction wouldn’t be much of a problem, however not every component of a traditional action is made out of wood.
Compression set
Since the screws that attach the flanges to the rails are made out of metal, they do not react to humidity. When a wooden flange expands around a metal screw it tightens around it and compresses the wood. This is called a compression set. Later in the year, when the
humidity falls, the wooden flange dries and contracts and is permanently smaller around the top of the screw. Because the screw is now loose and no longer holding the flange to the rail, it can rattle and parts can wobble when played. For this reason, most piano technicians routinely tighten action screws as part of their periodic tuning calls.
Of course, next summer the humidity rises again and another compression set is created. As this cycle of compression sets continues over the years, the wood in the flange can become irreparably damaged, leading to an expensive replacement procedure.
Wood strength is inconsistent
From piece to piece, wood strength is extremely inconsistent. Because wood is a natural, organic material (i.e. it grows) it cannot be precisely created or controlled. This results in some pieces being strong or weaker, even though they may look the same. Unfortunately, both weak and strong wood are used to build piano actions, and the weak wood generally outweighs the strong.
Strong wooden shank
Weak wooden shank
Strength inconsistency in wooden actions parts can be easily demonstrated through hammer shanks. If you try to bend a set of 88 wooden hammer shanks you’ll find that roughly only 10% of them are very strong and rigid, while the remaining 90% are weak and flex very easily.
Composite materials
The answer to a better piano action lies in composite materials. Not to be confused with simple plastics, a composite material is much more advanced and composed of two different materials. Typically, a composite starts with a type of plastic as its base, which is strong but too flexible, and then pairs it with a fiber, which adds rigidity. The result is a material that takes the best of both materials and merges them into one—similar to metal alloys such as stainless steel.
The iconic black composite material that Wessell, Nickel and Gross uses for its repetitions is custom-made to be remarkably strong, durable, and extremely resistant to humidity. Any part made from this composite material will not experience “tension release”, or expand or contract with the seasons—a perfect choice for piano actions.
Epoxy carbon fiber shanks
The epoxy carbon fiber tubes that Wessell, Nickel and Gross uses for its hammer shanks are both exceptionally strong and, importantly, consistently strong. These hammer shanks have been specifically designed to be as rigid and stiff as the ideal wooden shank, and ensure that the maximum amount of energy is transmitted from the hammer shank to the piano strings—resulting in maximum power and clarity.
Each epoxy carbon fiber shank is virtually identical in strength
Since epoxy carbon fiber is an inorganic material and not grown, it can be manufactured with precision and to tight tolerances—ensuring that every shank in a Wessell, Nickel and Gross piano action is as strong as the next and that every note will play at a reliable and consistent volume.
The "whipping" fallacy
The high-speed video below demonstrates that as a weak wooden shank travels upwards, it flexes and bends as it moves towards the piano strings—the result of using an inferior material. Some piano experts label or try to justify this bending motion as “whipping” and believe that it is actually a benefit, as they claim that the shank will “whip” back and hit the piano strings with extra force.
The entire point of a piano action is to transfer the energy that the pianist applies to the keys to the piano strings. Understanding this, basic physics easily disproves the idea that whipping or flex is beneficial to shanks. When a hammer shank flexes, energy that should have accelerated the hammer is absorbed in making the shank bend instead. As a result, the hammer will not hit the strings with as much force as it could have.
An excellent example of rigidity and energy transmission can be found in golf clubs. Before1929, most golf club shafts were made from wood. After this date, steel shafts became legalized for competitions and quickly became very popular, as they were much stiffer than wooden shafts. This increased stiffness allowed the steel clubs to transfer more energy to the ball, which in turn enabled the golfer to hit farther. Later, in 1973, carbon fiber (graphite) shafts were introduced, and are now considered to be the best, as they offer even more strength and energy transmission than steel shafts, but are also much lighter.
Additionally, wooden hammer shanks vary in strength considerably more than composite shanks. As a result, some notes will play louder than others. This variability in volume forces the pianist to compensate for the shortcomings of the action, rather than concentrating on the music. To remedy this, a piano technician can voice (tone regulate) the action. This typically means that the hammers on loud notes are needled to soften the tone to match the volume of the softer hammers—effectively hamstringing the notes that play well to match the notes that don’t. The consequence of this procedure is that the piano’s dynamic range, or margin of expression, is reduced and the piano won’t be able play to its full potential.
Striking with precision
Tonally, it is extremely important that the hammer hits the piano string in the right place. This is referred to as the strike point. A strike point is a specific point on the length of the piano strings that produces the clearest tone and loudest possible volume. As a general rule, the longer the string, the larger the strike point “window”. Since treble strings are much shorter than bass strings, their strike point “window” is much smaller—so small, in fact, that if a hammer hits the string even slightly off this point the note will have a dramatic reduction in volume and tone.
When a hammer shank flexes it can cause the hammer to miss the strike point. Additionally, some shanks may accurately hit the strike point at a medium volume, however, when played loudly, they might flex and not hit the strike point, causing the note to sound flat.
Like “whipping”, the procedure to remedy this is to voice the piano and make all the notes play at the same volume. Once again, the notes that play well are brought down and held back to match the level of the notes that play poorly.