Action Rebuilding
One of the biggest challenges in explaining the need for action rebuilding is the slow rate at which a piano action will deteriorate. It is so gradual, unless you know how your piano should play and sound, you may have no idea how far your piano has deteriorated. Here are some of the conditions we look for in determining the need for action rebuilding.
The most obvious reason to rebuild your piano's action is broken parts. While it is not unusual for an occasional part to break, multiple examples of the same part breaking means it is time to replace all of the parts. My threshold is 5%, which is generally 4 broken pieces, actually a rather high number. If a significant number of parts have been replaced it may be difficult or nearly impossible to maintain an even touch. Next check the color of the parts. When new, wooden action parts are usually made of maple or a similar wood and are very light (nearly white) in color. As the wood ages and oxidizes it will become darker. The darker the wood, the greater the deterioration at the cellular level, and the more brittle the wood becomes, increasing the risk of breakage. Hammers also start life white. As the wool ages and oxidizes it will turn yellow and lose all of its resiliency and elasticity. It ceases to be a flexible, springy hammer, becoming instead a hard non-flexible mallet. Long before any of this has happened though, the performance, both mechanically and musically, of the action has deteriorated. It may work and make a sound but not like it should.
At the very least, installing and regulation new parts can restore your piano to its original beauty. Yet even more can be done. Within a grand action there are many parts which must interact with each other. Most actions have an action ratio of about five. This means that everything which happens at one end of the mechanism has a 5 fold effect on the other end. If a new hammers weighs 2 grams more than the old hammer it will require 10 grams more pressure to play. The usual target for down weight (as it is called) is about 50 grams. If no compensatory actions are taken to accommodate the heavier hammers the action will now have a 60 gram down weight. A 20% increase. A keyboard with this high of a down weight will feel considerably "heavier" than a piano with a standard 50 gram down weight.
Two primary performance concerns which enter into the question of action rebuilding are the desired touch and the desired tone.
Here are some of the questions which need to answered to help bring your piano to its full potential:
- How do you want your piano to sound when everything is finished?
- What are the limits of the piano as it exists today? Can anything be done with the stringing scale? Or termination points to improve the tonal potential?
- Do you prefer a bright or a mellow tone?
- What types of music are usually played?
The brand of replacement hammer and their physical weight are all factored into the best answer to these questions.
Action rebuilding can be done to several different degrees.The least involved is to replace the hammers, shanks and flanges, that regulate the action.If conditions warrant it, or the pianist demands a more responsive action, the wippens can also be replaced with state of the art, fully adjustable wippens.
Here are some of the questions which must be answered involving touch:
- Do you prefer a light or heavy touch? (Remember who also plays this piano today and who may play it in the future, like an older, more arthritic you.) A "light" touch will usually have a down weight (the amount of weight required to bring the action to the point of let off) of 46 - 48 grams. A heavy touch would weight in the upper 50's grams. The "typical" down weight is about 50 grams.
- As with everything there are trade offs. A lighter down weight can necessitate a lighter up weight (the amount of weight the key can lift on it way from depressed to at rest) which will impact the responsiveness of the action. Up weights can range from 20 grams in an action with either a very light down weight or one with significant friction to the upper 30's in a piano with high down weights or unusual leverage arrangements.
- Inertial problems can be very difficult to diagnose. Inertia is the desire of a body to remain as it is, either moving or still. Inertia in a piano action comes from the lead found in the keys and their location. Also the contact points and locations of the components effect our experience of inertia.
- Inertia is closely related to geometry in the functioning of a piano action. Geometry deals with the point of energy transference; where in a lever is force applied. The difference of a millimeter can have an enormous impact depending on where that millimeter is located.
- A piano action has many moving parts which interface and contact other moving parts. Friction can come from the pins some of these parts move on in addition to the relationship of the arcs of movement between the various parts. Are the parts set up so that they roll against each other or do they slide? Some friction is good, too much is bad, the challenge is to find the right balance and right location for the friction.
So all of these different components must be balanced against each other, priorities set, and the limits of the instrument included in any decision. As these elements interact you will find certain psycho/physiological phenomenon occurring. Namely a bright piano (all things being equal) will "feel" lighter to play while a mellow piano will feel heavier to play because you may feel you must work harder to achieve your desired volume.
Action Rebuilding
- Custom hammers made by Ronsen Wurzon hammers to best match hammers from the Golden Age of piano manufacturing
- Action rebuilding using the latest parts form the best makers in the world
Action Redesign
- Action geometry problems solved
- Custom Action Balance (tm) available
