About Piano Hammers

A piano’s hammers are made of felt stretched over a piece of wooden molding. The hammer felts are subject to the greatest wear of all felts found in a piano. They are also the single most significant factor the influences the feel of your piano at the keyboard.

Piano Hammer DiagramOver time and use, hammers wear out and need to be replaced. How long a set of piano hammers will last depends on how often the piano is played. A teaching piano or a piano in an institutional setting (church, school, or university), may need replacement hammers in as little as 5 – 10 years. Pianos receiving only occasional use could go much longer. In addition, pianos that have sat idle for an extended period could possibly experience accelerated hardening of the hammers.

Why Replace Piano Hammers?

Replacing old hammers with new can add new life to a piano. Most noticeably will be the change in the tone of the piano. Older hammers that have hardened and lost their resiliency over time tend to produce a bright, tinny tone during play. Sometimes, old, hardened hammers are described as being loud.

In addition, piano hammer replacement can also serve to improve the keyboard feel of your piano. Hammers are the single most significant factor in how the keys feel to you, the player, while using the piano. A hammer that is too heavy—or too light as is the case with most older pianos—can cause the feel at the keyboard to be "off".

Further, hammer shanks and flanges can become too loose or too tight as they age. Actually it’s the hammer shank and flange pin which acts as the pivot point that loosens or tightens over time. The resulting feel to the player is a piano that is "too heavy" or "too light" to play. Sometimes, when the flanges become extremely loose, the piano action can actually feel uncontrollable.

A professionally installed new set of hammers, shanks, and flanges for your piano can fix all of these concerns.

The video clip above walks through some basic principles of an excellent piano hammer replacement job.

Full top to bottom piano hammer tapering

A grand piano hammers showing the essential, but often overlooked, full top to bottom taper. This provides the necessary clearance within the action, as well as allows the mass of the hammer to be controlled for optimum touch weight and keyboard feel.

Proper fitting of a new set of piano hammers is essential. Particularly in grand pianos. Full tapering to provide adequate clearance, as well as proper mass of the hammer is an often overlooked step. Arching the inside of the hammer molding (sometimes called the cove) is also a frequently skipped area—again essential for proper hammer mass. Lastly, the back of the hammer molding should be properly cut and shaped to allow optimal interface with back checks.

These principles apply to grand piano hammers only, but similar techniques are also recommended with uprights, depending on the particular piano.

How Does the Piano Hammer Work?

Think of a xylophone or a drum. A mallet is used to strike the bars of a xylophone to create the sound you hear. A drumstick is used to strike the "skin" on a drum to create a percussive sound.

Piano Hammers Striking Strings

Piano hammers striking strings on an upright piano.

Consider the piano hammer in the same fashion. Very simply, the hammer strikes the string(s) and creates the sound you hear. One major difference between drumsticks, mallets, and piano hammers, however, is the piano hammer’s ability to "spring." A drum stick or xylophone mallet is controlled by the player. That is, the player directly holds the mallet and controls the strike. A piano hammer is not directly held or controlled by the piano player. Yes, it is true that the piano player uses the keyboard to activate the hammers, but this is considered indirect control.

There are two opposing forces present in a piano hammer that provide it the ability to spring or rebound from the string after striking: tension and compression. Highly compressed felt is formed around a wood core under tremendous pressure.

Were Piano Hammers Always Made of Felt?

No! The very first piano hammers were made of wooden heads covered with leather. Felt hammers have been a standard since around 1830.

What Difference Does It Make If My Piano Hammers Are Hard?

The hardness of a piano hammer has a great deal of influence on the resulting piano sound. Hard hammers are better at exciting high frequency modes of a piano string’s vibration so that the resulting tone quality may be characterized as being bright, tinny, or harsh. Soft hammers, on the other hand, do not excite high frequencies very well, and the resulting tone is somewhat dull or dark. Or, in short, harder hammers produce brighter tones, while softer hammers produce more mellow tones.

The video clip above shows some of the incredible sounds from a vintage, antique upright piano that has been restored with (among other things) new hammers, new action parts, and new strings.

If you look at the hammers on a piano carefully, you will notice that the felt is thicker on the left side of the scale, or the bass side. The felt thicknesses progressively decrease as you move up the scale to the high treble. One reason for this is the statement of fact above: Hard hammers excite (or produce) high notes better than soft hammers, and vice-verse.

Hammer Voicing and Shaping

Worn Piano hammers with Deep Grooves Present

Worn Piano hammers with Deep Grooves Present

One of the most common problems we encounter with hammers is excessive hardness or excessive grooving from the strings, which negatively impacts the tone and sound of the piano. One way to abate this is regular hammer voicing and/or shaping. Voicing techniques can alter the hardness of individual hammers (or groups of hammers) on a piano to improve (or change) the resulting tone. Shaping techniques can remove the string grooves and provide the full surface of the hammer for striking, again improving tone and performance. It is worth mentioning, however, that very old hammers or those that are excessively worn will likely not benefit much from voicing or shaping.

Finer Points of Piano Hammer Replacement: Improving Playability and Piano Action Performance

The video clip above discusses some of the finer points of piano hammer replacement with a focus on improved playability and piano action performance—not just the tone and sound of the piano.

Our Process for Replacing Your Piano Hammers

If you have decided to proceed with new piano hammers, there are some key points we will discuss with you. These will allow us to better select a specific set of new piano hammers for you and your piano. For example, we will ask you about the following:

  • What type of tone are you seeking? Mellow? Bright? Something in between?
  • Are you happy with the feel of the keyboard? If not, what would you change? Is it too light? Too heavy?
  • Do you have any other concerns with your piano and its playability?

Your answers to these questions can help us help you. Most piano owners are not aware that during a hammer replacement project, we can actually adjust your piano’s touch weight (keyboard feel) to your liking. If you prefer a heavy or light touch, we can dial that in for you. As mentioned previously, since piano hammers are the single most influential component of keyboard feel and touch weight, when we replace your piano’s hammers, we can tailor the new set to your preferences.

There are several piano hammer manufacturers out there, and each product line offers a little something different in terms of tone and sound. By understanding what you are trying to achieve in this regard, we can select the best choice for you.

If you have concerns with other playability issues such as a loss of control or a very inconsistent feeling across the 88 keys, we can fix that as well during hammer replacement. And, the best part is that making your keys feel consistent up and down the scale, improving your piano’s tone, and fine tuning your piano’s touch weight do not add anything to the cost of replacing your piano’s hammers. That’s right—our hammer replacement jobs include all of these "finer points" at no additional cost to you. Note that additional costs do apply for replacement of shanks and flanges as described in the video clip above.


If you are not happy with the tone of your piano (or the appearance of the hammers), please contact us. We would be happy to review options from voicing/shaping to complete hammer replacement with you.piano