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Why Are The Hammers Important On A Piano?

Many people underestimate the importance of the hammers in the piano. When a key is depressed it creates a chain reaction which levers the hammers in to hitting and rebounding off the string. Although this process is important, if the hammers are badly made, shaped or toned this will drastically effect the tone and playability of the instrument. Continue reading to find out more.

Construction of the Hammer Head

The basic construction of a piano hammer is a hard wood molding with very hard dense wool felt wrapped around it. In the best pianos this felt is in two layers, an underfelt and an outer felt. This underfelt is usually brightly coloured whereas the outer felt is a white/cream colour.

The hammer head wood molding is first cut in to individual pieces. These are then clamped tightly back together. A single layer or laminated layer of the wool felt is then wrapped and glued tightly around the hammer heads with a huge amount of pressure from a machine. This helps to create the right amount of density and compression in the hammer for correct tone. Once dry, the felt is cut down the sides of the wood to create the individual hammer heads. In older hammer heads a staple might have been added to help hold the felt on the hammer head. This is less important now that we have waterproof glues and better making methods.

Felt Orientation

An important factor is the felt that is used. The best hammer heads have a colourful underfelt which adds density to the hammer. The top felt on the best hammer heads has long fibres that run parallel to the strings. These wear better than the alternative which is short fibres perpendicular to the strings. These are less dense and groove easily after playing.


After ensuring the hammer head has been made with the best materials and the best way it still needs to be shaped correctly. Hammer shape can change the tone of the piano tremendously. All hammers are an approximate tear drop shape however the tip of the hammer head is different in different makes and eras of piano. A general rule is that a pointier hammer end will have a brighter tone and a rounder hammer end will be more mellow.

This must be taken in to consideration as a piano maker but as a restorer/technician a rule of thumb is to return the hammer head shape to whatever it was when it was originally installed in the piano. Some hammers have a chamfer which needs to be maintained to avoid the hammers rubbing on each other. This is just one reason to always have a professional reshape the hammers on the piano as this can make or break your piano sound and therefore your enjoyment.

Why Are The Hammers Important On A Piano? Picture of hammer heads
Example of hammer wear leading to poor shape and the correction. Source:

Strike Point

It is very important to make sure that the hammers strike at the correct point on the string. This is to do with how long the hammer shank is, the angle at which the hammer head is glue on from every plane and the geometry of the piano and scaling. Complicated but crucial!

Alignment and Travelling

During the regulation process hammers are travelled to the string. This means they are orientated so that they go in a straight line to the string. Any hammer moving at an angle is losing momentum and thus striking power. Along with this it is important to make sure that the hammer is hitting with an orientation where the strings are spread evenly over the striking point of the hammer head.


After all of that, you still need to tone the hammers correctly. This is best done after careful shaping, refacing - a more detailed shape with differing grades of sand paper - matching the hammer to the string to ensure it strikes all three strings in unison correctly, and proper tuning. At this point the hammers can be toned using needles to change the density of the hammer head in certain areas to create a more pleasing and even tone throughout. In some extreme cases specific solvents and methods are used to bring a very bright piano down to be more mellow, and the inverse is true. This is a specialism in itself and requires patience, time, good hearing, a good understanding of the methods used and when to say enough is enough!

In the above article we have covered some of the most important elements of why hammers are so important in the playability of your piano. The durability, overall sound and tone of the instrument will be incredibly affected and as a consequence, how much you enjoy playing your instrument and the overall money you need to spend on it! Please bare in mind this is not an exhaustive list and is written in terms to be understood by the general public.

We hope you have enjoyed this article Why Are Hammer Important? and it has helped you understand some of the key elements.

Why Are The Hammers Important On A Piano? Hammers
Hammer Heads shaped and to the strike point


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