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Piano Hammers - important things to know about correct hammer tone and weight.
General information
Piano hammers are made of compacted wool. The hammer strikes the string causing it to vibrate. The hardness and shape can greatly change the tone of the piano. To help understand this, imagine a drum being played with a stick compared to a soft felt. The stick produces a very harsh sound and also brings out the high harmonics. A soft felt produces a mellow sound and brings out the low tones. So a hard piano hammer sounds bright and emphasises the high tones, whereas a soft one sounds mellow and emphasises the low tones. Furthermore, as hammers wear, they can become very flat at the striking point and this prevents the harmonics being produced properly. The ensuing tone can therefore be lifeless. Reshaping the hammers can put life back into the tone, though it also makes the hammer thinner so it doesn't bounce so well. So it may still sound lifeless. Gererally hammers can be reshaped once, but more than this they become too thin. It's extremely common to find older pianos that have very worn or soft hammers. We often find top makes of piano such as Bluthner or Steinway which have been played extensively and have never had their hammers refaced or changed, and clients are amazed at the transformation that ensues when this is done!
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Steinway hammer identified by the colour of the under-covering - yellow on older Steinways and purple on modern ones . In Europe today they are made by Renner, who also make the identical hammer for other firms, but with a different colour of under covering or no undercovering at all. The under-covering is largely cosmetic. The two main European hammer makers are Renner and Abel. Renner's standard under covering colour is red and Abel's is green.
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This illustration shows different hammer shanks by Renner, common woods being hornbeam and beech. The roller is hard felt covered with buckskin and is a crucial part effecting the touch. Changing old rollers often makes a lot of difference to the touch, making it smoother.
Voicing or toning hammers - vital information.
Assuming the piano is a high quality make such as a Bluthner or Steinway, the tone of the piano only reaches its full potential when the hammers are in good condition and professionally toned.
When the hammers are manufactured the compressed felt is pulled round the wooden centre under great pressure. When the new hammers are fitted to the piano the felt is tight and needs to be loosened at the shoulders or "cushion" and also at the base or "battery" area. This allows the hammer to bounce cleanly off the string, bringing out the partials and giving it an open singing tone.
Voicing is the art of opening up the felt by pricking or "stitching", as it is called, with needles. The first stitching is done either in the battery or in the cushion area. Each hammer is deep needled between up to 40 times in the bass tapering to about 10 in the top treble. Not all hammers are the same so this job needs to be done with a lot of patience and care, listening all the time to the result.
The process of stitching is combined with filing the hammers, usually to give them a more pointed shape.
Before proceeding to fine toning, it's essential to make sure the hammers for the trichords and bichords strike all the strings simultaneously. Either the strings themselves may not be level, especially if the piano is restrung, or the hammers may not be exactly level at the striking point. A badly lined hammer has a huge effect on the tone which will be weak, poor and thin sounding.
Finally the striking point of the hammers can be gingerly toned, taking care not to go deeper than about 3mm as any deeper will irrevocably damage the hammer. This cannot be over stressed.
The process is of course more involved than this, and it's not a job to be attempted lightly. Fine hammer voicing normally takes about 8-12 hours.
TONING OLDER HAMMERS
Older hammers are usually indented or even flat along the striking point. They need to be restored to their original shape, though the indentations should not be completely removed as they are a useful guide for further work.
The toning procedure will then vary according to whether the hammers are hard or soft. If they are hard, then they can be toned with the above processes. If they are soft they will need bringing to a point and then sanded with very fine grade paper and ironed. The top ten or so hammers may need doping with a chemical such as cellulose lacquer.
CONCLUSION
We find many used pianos fitted with new hammers that haven't been toned at all. The result is a harsh tone and often heavy touch. The good news is that provided the strings and soundboard are good, the pianos can be transformed with a day or two's work voicing the hammers. That's providing the hammers were correctly fitted and from a good company such as Renner or Abel.
Finally new hammers take a while to reach their optimum tone and the final toning is best done in the location the piano will be played as for instance a large room will require louder hammers than a small one.
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Steinway hammer identified by the colour of the under-covering - yellow on older Steinways and purple on modern ones . In Europe today they are made by Renner, who also make the identical hammer for other firms, but with a different colour of under covering or no undercovering at all. The under-covering is largely cosmetic. The two main European hammer makers are Renner and Abel. Renner's standard under covering colour is red and Abel's is green.
|
|
This illustration shows different hammer shanks by Renner, common woods being hornbeam and beech. The roller is hard felt covered with buckskin and is a crucial part effecting the touch. Changing old rollers often makes a lot of difference to the touch, making it smoother.
Voicing or toning hammers - vital information.
Assuming the piano is a high quality make such as a Bluthner or Steinway, the tone of the piano only reaches its full potential when the hammers are in good condition and professionally toned.
When the hammers are manufactured the compressed felt is pulled round the wooden centre under great pressure. When the new hammers are fitted to the piano the felt is tight and needs to be loosened at the shoulders or "cushion" and also at the base or "battery" area. This allows the hammer to bounce cleanly off the string, bringing out the partials and giving it an open singing tone.
Voicing is the art of opening up the felt by pricking or "stitching", as it is called, with needles. The first stitching is done either in the battery or in the cushion area. Each hammer is deep needled between up to 40 times in the bass tapering to about 10 in the top treble. Not all hammers are the same so this job needs to be done with a lot of patience and care, listening all the time to the result.
The process of stitching is combined with filing the hammers, usually to give them a more pointed shape.
Before proceeding to fine toning, it's essential to make sure the hammers for the trichords and bichords strike all the strings simultaneously. Either the strings themselves may not be level, especially if the piano is restrung, or the hammers may not be exactly level at the striking point. A badly aligned hammer has a huge effect on the tone which will be weak, poor and thin sounding.
Finally the striking point of the hammers can be gingerly toned, taking care not to go deeper than about 3mm as any deeper will irrevocably damage the hammer. This cannot be over stressed.
The process is of course more involved than this, and it's not a job to be attempted lightly. Fine hammer voicing normally takes about 8-12 hours.
TONING OLDER HAMMERS
Older hammers are usually indented or even flat along the striking point. They need to be restored to their original shape, though the indentations should not be completely removed as they are a useful guide for further work.
The toning procedure will then vary according to whether the hammers are hard or soft. If they are hard, then they can be toned with the above processes. If they are soft they will need bringing to a point and then sanded with very fine grade paper and ironed. The top ten or so hammers may need doping with a chemical such as cellulose lacquer.
CONCLUSION
We find many used pianos fitted with new hammers that haven't been toned at all. The result is a harsh tone and often heavy touch. The good news is that provided the strings and soundboard are good, the pianos can be transformed with a day or two's work voicing the hammers. That's providing the hammers were correctly fitted and from a good company such as Renner or Abel.
Finally new hammers take a while to reach their optimum tone and the final toning is best done in the location the piano will be played as for instance a large room will require louder hammers than a small one.
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