Abstract:
The invention relates to a key for pianos, comprising a pivotably supported key body consisting of a soft wood and adjustment means for adjusting the touch load of the key. A plate-shaped element of a different specific weight is inserted into the key body. The position and weight of the plate-shaped element is selected such that a desired touch load of the key is almost accomplished. The weight of the plate-shaped element is varied slightly by inserting an additional weight, in particular a setscrew, or by forming a recess in such a manner that the desired touch load of the key is accomplished. The plate-shaped element consists of a composite wood material comprising a press-formed resin-wood layer formed of wood veneer layers, which are impregnated with a resin under a vacuum and glued to each other while applying pressure and heat to accomplish a very high specific weight.

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority of U.S. provisional patent application Ser. No. 60/954,069 “Key For a Music Instrument and Method for Manufacturing the same”, filed on Aug. 6, 2007, the whole content of which is hereby incorporated by reference. The present application corresponds to German patent application no. 10 2007 036 857.9 “Key For a Music Instrument and Method for Manufacturing the same”, filed on Aug. 6, 2007, now granted as German patent no. 10 2007 036 857. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates in general to keys for music instruments and methods for manufacturing the same and relates in particular to the adjustment of a predetermined touch weight or touch load of a key for keyboard instruments, particularly for the mechanism of grand pianos or acoustic pianos. 
       BACKGROUND 
       [0003]    The adjustment of a predetermined touch load is very important for accomplishing a desired touch feeling with acoustic pianos or grand pianos. For this purpose it is known to dispose two or more weights, usually consisting of lead, in the front end of a key (in the following also front end key), with fixed connection relative to the respective key, which weights form the counter-weights to the part of the mechanism resting on the rear lever and define the predetermined touch load, e.g. a touch load of 45 grams or 50 grams. The number and position of the lead members to be inserted into the key for this purpose is variable and is respectively determined by a piano technician in the factory. The costs for this particular job are rather high. 
         [0004]      FIG. 1  shows particulars of this conventional approach. More specifically,  FIG. 1  shows a key  100  on which also the approach according to the present invention shall be applied. According to  FIG. 1 , the key  100  comprises an elongated, rectangular key body  102 , which consists of a softwood, e.g. of spruce wood or pine wood, and which has a relatively small weight. In the front region the key body  102  is covered by an L-shaped key cover  104 , which is e.g. of acrylic. A middle plate  105  is adhered in a central region on the top of the key body  102  and a balance pin hole  106  extends through these members in vertical direction. This balance pin hole  106  is engaged with an upright balance pin (not shown) to swingably support the key. Furthermore, the key body  102  is provided in the known manner with a front pin hole  114  in a front edge region of the bottom face thereof, which is engaged with an upright front pin (not shown) to prevent horizontal deflection of the key  100 . A capstan screw  108  is attached at a position behind the balance pin hole  106  on the top face of the key body  102  through a capstan plate  107 . An action (not shown) is supported on this capstan screw  108 . With the foregoing configuration, when a front portion of the key  100  is pressed downward, the key  100  swings about the balance pin (not shown) causing the capstan screw  108  to push up the action for its actuation. The so-called touch load of the key is determined by the balance of a moment produced by the weight of the action and the key  100  about the balance pin. 
         [0005]    According to  FIG. 1 , for adjusting or regulating the touch load conventionally a plurality of boreholes  109  are formed in the front side face of the key body  102 , into which cylindrical lead members  110  are inserted and caulked in the known manner. The position of the boreholes  109  is variable, in correspondence with the desired touch load. 
         [0006]    This approach is elaborate and costly and not up to date for environmental reasons due to the usage of lead as material of high specific weight. 
         [0007]      FIG. 2  shows an alternative approach according to the prior art, as disclosed e.g. in DE 102 33 001 A1 or corresponding U.S. Pat. No. 6,774,294 B2. A plurality of embedding holes  109  are disposed at predetermined positions on the front side face of the key body  102  spaced apart to the balance pin hole  106  and at a predetermined spacing relative to each other. Cylindrical threaded pins  110  having an external thread  113  are used, which are made of a material other than lead, preferably of iron. The threaded pins  110  of a predetermined diameter and of a predetermined length are screwed into the embedding holes  109  for adjusting a desired touch load, using a screwdriver. This approach, however, bears the risk of crack formation in the softwood material of the key body  102 . Namely, in order to prevent warping of the key member  102 , the fibre direction of the softwood material of the key body  102  extends in parallel with the bottom side of the key body  102 . This is indicated in  FIG. 2  by two lines  124 , which are to designate in an exemplary manner the fibre direction of the softwood material. Even though the embedding holes  109  are formed within the softwood material with a diameter slightly smaller than the diameter of the external thread  113  of the capstan screw  110 , screwing in the capstan screws  110  in the direction of the fibre planes of the softwood material of the key body  102  causes the individual fibre planes of the softwood material to be pushed away from each other upon screwing-in of the capstan screws, which is detrimental due to the known cracking proneness of such softwood materials. This cracking is aggravated significantly, if the key mechanism is stored under humidity which is too low. 
         [0008]    When fine-tuning a keyboard, the piano technician is demanded to show a sure instinct so that fine-tuning is still rather elaborate. As can be derived from  FIG. 2 , a plurality of adjusting weights are still required for adjusting a predetermined touch load, which increases the risk of crack formation further. Overall, the aforementioned approach is thus of limited use only for the industrial manufacturing of keyboards and represents a significant expense factor; but still a certain percentage of defective keys has to be taken into account due to the aforementioned crack formation. 
         [0009]    U.S. Pat. No. 6,531,651 B2 discloses a similar approach. As an alternative to usage of adjustment weights DE 1 064 325 B discloses a key comprising a groove-shaped recess in the front portion of the key extending in the longitudinal direction of the key, a weight for adjusting the touch load being supported movable in longitudinal direction on a threaded spindle within a frame corresponding to the groove-shaped recess, a regulating shaft being provided for enabling a displacement of the weight, said regulating shaft preferably acting onto the threaded spindle via bevel gears. Also this approach is elaborate and is only of limited use for manufacturing keyboards on an industrial scale. 
         [0010]    DE 102 48 000 A1 (corresponding to U.S. Pat. No. 6,693,235 B2) discloses an alternative approach for reducing the risk of breakage of the key body. An additional front plate is put onto the key body, into which an adjustment weight is inserted. An insert hole is formed in the key body, which extends in vertical direction through a front plate up to the key body. An adjustment weight, which consists of a material other than lead, is inserted into the insert hole by a press-fit and attached to the key body. While the key body is formed of a softwood material, the front plate is formed of a harder and hence heavier wood. With this configuration also a certain adjustment of the touch load of the key is accomplished. For geometrical reasons, however, the adjustment weight can only be attached behind the balance point of the key body, which is not so convenient for the adjustment of the touch load due to the lever arms prevailing. Also this approach is only of limited use for the manufacturing of keyboards on an industrial scale. 
         [0011]    DE 1 244 541 B1 discloses a method for attaching a key cover to a key body. U.S. Pat. No. 5,585,582 discloses an automatic method for adjusting the touch load of keys of a grand piano. 
       SUMMARY 
       [0012]    It is an object of the present invention to provide a key for music instruments, in particular for acoustic pianos or grand pianos, which can be manufactured in a cost-efficient manner and using industrial processing techniques, and wherein the touch load (touch weight) can be adjusted easily and in a cost-efficient manner. According to further aspects of the present invention there is also to be provided a method for manufacturing such a key and a method for adjusting the touch load (touch weight) of such a key. 
         [0013]    Thus, the present invention relates to a key for a music instrument, comprising a key body, which is pivotably or swingably supported, and adjustment means for adjusting or regulating a touch load (touch weight) of said key. According to the present invention the adjustment means comprises a plate-shaped element, which is inserted into said key body or is connected with said key body, the specific weight of said plate-shaped element being different to that of said key body. According to the present invention the plate-shaped element is a multi-layer composite wood material, wherein at least one adjustment weight is inserted into said plate-shaped element and/or at least one recess is formed within said plate-shaped element to thereby adjust said touch load of said key. 
         [0014]    According to the present invention, the plate-shaped element substantially serves to enable a coarse adjustment of the touch load so as to be almost equal to the desired touch load, which is e.g. specified by a particular manufacturer of pianos or grand pianos. The additional adjustment weight or the additional recess represents a supplemental measure of a relatively small impact for precisely adjusting the desired touch load. According to the present invention only a relatively small weight variation in a region spaced apart to the balance point of the key body is necessary for this purpose, so that according to the invention less adjustment weights or adjustment recesses are sufficient to enable a precise adjustment of the touch load. Particularly preferably according to the present invention only a single recess or a single adjustment weight is provided within the plate-shaped element. 
         [0015]    The material of the plate-shaped element and the physical and mechanical characteristics thereof are parameters that can be varied easily to enable an appropriate adjustment of the weight distribution of the key body, optimizing production engineering aspects, e.g. the joining with the softwood material of the key body and a substantial reduction of the aforementioned risk of crack formation, for which purpose the configuration of the front end of the key body can be modified. 
         [0016]    Preferably, the plate-shaped element comprises uniform side faces that are preferably regularly formed so that the plate-shaped element can be inserted easily into the key body using wood processing machines and simple industrial processing steps. 
         [0017]    Overall the approach according to the present invention turns away from conventional principles, according to which a plurality of relatively small but heavy adjustments weights had to be inserted at positions that had to be determined individually for enabling an adjustment of the touch load. In comparison to the prior art the plate-shaped element according to the present invention is rather long in the longitudinal direction of the key body so that according to the present invention the weight distribution of the key body can be varied not only locally but in a rather large-area portion. 
         [0018]    Even more preferably the plate-shaped element is formed of a composite wood material, whose organically grown fibre structure has been removed completely. In particular, such composite wood materials can be formed on an industrial scale with reproducible properties. In particular, the specific weight can be precisely set for such a composite wood material. 
         [0019]    According to a further embodiment the plate-shaped element is a rectangular plate, in particular a cuboid, which extends in the longitudinal direction of the key body and is disposed on only one side of the balance point of the key body and spaced apart therefrom. It is of advantage that the rectangular plates can be inserted precisely into the softwood material of the key body or attached to the front end of the key body using simple industrial processing steps. Basically, the position of the plate-shaped element does not have to be specified with high precision, because according to the present invention the touch load is precisely adjusted by an additional measure, namely the adjustment weight or the recess. 
         [0020]    The plate-shaped element is flush with the bottom side and side faces of the key body. In general, the external appearance of such a key is not different as compared to conventional key, which is also an important precondition for the replacement during the manufacturing of conventional keyboards or repairing of existing keyboards. 
         [0021]    Preferably, the plate-shaped element is formed of a wood material, wherein the organically grown, fibrous structure does not exist anymore so that the afore-mentioned risk of crack formation does not exist anymore. Thus, adjustment weights can be engaged with or inserted into the plate-shaped element regardless of the orientation relative to the plate-shaped element and without the risk of crack formation. Thus, according to the present invention the respective adjustment weight can be engaged with under arbitrary angles and orientations and in general at any side face of the plate-shaped element. 
         [0022]    Particularly preferably the plate-shaped element is formed of a composite wood material, because the organically grown, fibrous structure is completely removed in such a composite wood material. In particular, composite wood materials can be produced on an industrial scale with reproducible characteristics. In particular is it possible to precisely adjust the specific weight of such a composite wood material. 
         [0023]    Preferably, the composite wood material is a multi-layer composite wood material, which can comprise e.g. a press-formed resin-wood layer, which is formed of wood veneer layers which are layered lengthwise, cross-wise, star-like or the like relative to each other. These veneer layers can be impregnated, e.g. using a vacuum method, and can be glued by means of curable resins under pressure and heat. In this manner composite wood materials having a relatively high specific weight can be produced, which also exhibit substantially the characteristics of wood, i.e. which naturally mate to the softwood environment in the key body and thus enable a durable joining with the softwood material of the key body. Particularly high specific weights can be accomplished using hardwood materials, such as beech wood, maple wood, oak tree wood or the like, for forming the composite wood material. 
         [0024]    According to a further embodiment preferably so-called Panzerholz® from Delignit® is used as the composite wood material. Such composite wood materials are characterized by a relatively high specific weight and by a high hardness and durability. 
         [0025]    Of course, the composite wood material generally may comprise also layers of different materials, such as thin metal sheets, ceramic layers, mineral layers or the like, for enabling the setting of an even higher specific weight and the additional variation of the mechanical properties of the composite wood material. 
         [0026]    Generally, the present invention is, however, not limited to usage of wood materials or composite wood materials for the plate-shaped element. Generally the plate-shaped element generally may consist of any other material, such as metal sheets, metal foams, ceramic or metal sintered members or the like, so that the specific weight and the mechanical properties of the plate-shaped element may be varied according to the present invention within wide-ranged limits. Preferably, according to the present invention only a single plate-shaped element is inserted in or engaged with the key body, which is of advantage for costs reasons and production engineering reasons. Conveniently, the plate-shaped element is joined with the softwood material of the key body using an appropriate non-positive joining, connections with force transmission by friction and/or adhesive bonding. Dovetail connections, toothings, so-called lap connections or also so-called shifting-connections turned out to be particularly convenient. 
         [0027]    Even more preferably only a single weight is inserted into the plate-shaped element or only a single recess is formed therein. As the weight distribution of the key body can already be adjusted by means of the plate-shaped element in such a manner that the desired touch load is almost accomplished, according to the present invention only relatively marginal variations of the weight or weight distribution of the plate-shaped element are required for the precise adjustment of the touch load, for which purpose generally only a single adjustment weight or a single recess is sufficient. 
         [0028]    According to the present invention nearly arbitrary materials can be used for the precise adjustment of the touch load, even materials having a lower specific weight. Thus, use of lead or lead alloys can be dispensed with completely. Conveniently, according to the present invention the adjustment weight is formed as a threaded pin or set screw, e.g. as an Allen threaded pin or as a recessed threaded pin, which is screwed into the plate-shaped element at a predetermined position from a side or from the bottom side of the key body. 
         [0029]    According to a further embodiment, the respective adjustment weight, particularly the threaded pin, consists of a hard metal, in particular of a sintered carbide hard metal. Hard metals, which are composite materials, are characterized besides by a very high hardness, wear-resistance and a particularly high warm hardness also by a high specific weight. Hard metal consists mostly of 90-94% tungsten carbide (reinforcement) and 6-10% cobalt (matrix), wherein the grains of tungsten carbide are of a size 0.5-1 microns in average and wherein the cobalt fills interstices. Sintering resides in that a hard material having a high melting temperature, i.e. carbide, is mixed, in a finely dispersed state, with a second material (supplementary body) having a lower melting temperature and heated to temperature below the melting temperature of the carbide, temperature and duration of the heating step being chosen such that the carbides agglomerate. Besides conventional hard metals on the basis of tungsten carbide, also hard metals, which comprise only titan carbide or titan nitride as hard materials, may be used, wherein the binding phase consists e.g. of nickel, cobalt and molybdenum (also called Cermets (ceramic+metal). Generally, according to the present invention also cast hard metal can be used. 
         [0030]    According to a further aspect of the present invention, the adjustment weight is glued into the plate-shaped element so that the adjustment weight is not necessarily formed as a threaded pin. 
         [0031]    A further aspect of the present invention relates to a method for manufacturing a key for music instruments, in particular for acoustic pianos or grand pianos. At first a rectangular plate of a soft wood material is provided, e.g. of pine wood or spruce wood. Afterwards, a recess is formed near a front end of the rectangular plate, which extends along a first direction of said rectangular plate, preferably in parallel with a longitudinal edge of said rectangular plate, e.g. by milling a profiled recess. Afterwards, a correspondingly formed plate-shaped element is inserted into or engaged with said recess, said plate-shaped element having a specific weight which is different to the specific weight of said soft wood material. Finally, a plurality of key bodies are cut from said rectangular plate by cutting along a second direction perpendicular to said first direction, e.g. by laser cutting. 
         [0032]    Thereby the weight of the plate-shaped element is designed such that the desired touch load of the key is almost reach or exceeded only slightly. Thus, for the precise adjustment of the touch load only a marginal modification of the weight or of the weight distribution of the plate-shaped element is necessary, as described above. 
         [0033]    As an alternative to inserting or engaging a plate-shaped element the latter can also be joined with the plate-shaped element of softwood material in the region of the front face and along said first direction of said plate-shaped element. For this purpose, generally any connections with force transmission by friction, a non-positive joining, positive-fitting and/or adhesive bonding techniques are suitable. 
         [0034]    A further aspect of the present invention relates to a method for the preferably automatic adjustment of the touch load of a key produced in such a manner, which is pivotably supported about a balance point. Further details of such a method shall be described in the following referring to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0035]    Hereinafter the invention will be described in exemplary manner and with reference to the accompanying drawings, from which further features, advantages and problems to be solved may be derived, wherein: 
           [0036]      FIG. 1  shows the key of a grand piano according to the prior art having lead weights for adjustment of the touch load; 
           [0037]      FIG. 2   FIG. 2  shows another key of a grand piano according to the prior art of a lead-free material for adjustment of the touch load; 
           [0038]      FIG. 3  is a schematic partial cross section of a key according to a first embodiment of the present invention; 
           [0039]      FIG. 4  is a schematic partial cross section of a key according to a second embodiment of the present invention; 
           [0040]      FIG. 5  is a schematic partial cross section of a key according to a third embodiment of the present invention; 
           [0041]      FIG. 6  is a schematic partial cross section of a key according to a fourth embodiment of the present invention; 
           [0042]      FIG. 7  is a schematic partial cross section of a key according to a fifth embodiment of the present invention; 
           [0043]      FIG. 8  is a schematic bottom view of a key according to another embodiment of the present invention; 
           [0044]      FIG. 9  is a schematic plan view of a rectangular plate of a softwood material and having a material insert for manufacturing of a key according to the present invention; and 
           [0045]      FIG. 10  is a schematic flow diagram of a method according to the invention for adjustment (preferably automatic adjustment) of the touch load of a key according to the present invention. 
       
    
    
       [0046]    Throughout the drawings, identical reference numerals designate identical or substantially equivalent elements or groups of elements. 
       DETAILED DESCRIPTION 
       [0047]      FIG. 3  shows in a partial cross-section the front end  3  of a key having an overall configuration, which is essentially similar to that described above with reference to  FIGS. 1 and 2 . According to  FIG. 3  a material insert  15  is inserted into the front end  3  of the key, said material insert  15  being formed as a rectangular plate. The material insert  15  extends in a direction perpendicular to the plane of drawing of  FIG. 3 , preferably over the entire width of the front end  3  of the key. The material insert is inserted into a recess of corresponding shape, which is formed within the front end  3  of the key. This can be accomplished e.g. by performing a milling process, as will be described with reference to  FIG. 9  below. The material insert  15  is glued in the front end  3  of the key and is flush with the rear side and the side faces of the front end  3  of the key. 
         [0048]    According to  FIG. 3  the material insert  15  according to the present invention consists of a wood composite material comprising a plurality of material layers  15 ,  16  having different characteristics, which are disposed in an alternating manner. The plurality of material layers  16 ,  17  together form a multi-layer wood composite material which has a different specific weight as compared to that of the soft wood material of the front end  3  of the key. The individual layers  16 ,  17  can be veneer layers that are glued to each other under pressure, preferably of hard wood such as beech tree, maple tree or oak tree, which are layered lengthwise, crosswise or star-like or in an arbitrary other suitable manner. Such veneer layers can be impregnated under vacuum conditions with curable resins and can be glued together by curable resins under high pressures and high temperatures. A preferable wood composite material is so-called Panzerholz® commercially available from Delignit®. Such wood composite materials are available with specific weights e.g. in the range between 0.9 and 1.4 g/cm 3 . 
         [0049]    The shape, weight and position of the material insert  15  is selected such that the touch load (touch weight) of the key, if the insert is inserted into the key, differs but slightly from the desired touch load, e.g. by ±20%, more preferably by ±10% and even more preferably by ±5%. The actual touch load caused by the material insert can be slightly higher or lower than said desired touch load. In order to precisely adjust the desired touch load, according to  FIG. 3  a setscrew or threaded pin  18  of a lead-free material, e.g. of a metal different from lead or of a lead-free alloy, is screwed into the material insert  15 . Position and weight of the setscrew  18  precisely defines the touch load. If the desired touch load is exceeded due to the material insert, it is possible to provide a recess instead of the setscrew  18  as an alternative. 
         [0050]      FIG. 4  shows an alternative embodiment, wherein the threaded pin  18  slightly protrudes from the bottom side of the key body. According to  FIGS. 3 and 4  the threaded pin  18  is screwed into the material insert  15  perpendicularly to the layer sequence  16 ,  17 . As an alternative, the threaded pin  18  can also be screwed in from the side face of the key body, i.e. along the individual layers  16 ,  17 . Even in the latter case this does not result in crack formation within the material insert  15 , because the organically grown fibre structure is broken due to the material composite. In any case the formation of cracks within the softwood materials of the front end  3  of the key body can be prevented. 
         [0051]    As shown in  FIG. 5 , generally also plural threaded pins  18  can be used for a precise adjustment of the touch load. These may be screwed in at regular distances relative to each other or at positions that can be predetermined in an arbitrary manner. 
         [0052]      FIG. 6  shows an alternative embodiment, according to which the threaded pin  18  runs completely through the material insert  15  and extends up to the softwood material of the front end  3  of the key body. It is expressly noted that also in this case the threaded pin  18  only serves to enable the attachment of the material insert  15  in the softwood material of the front end  3  of the key body. 
         [0053]      FIG. 7  shows an alternative embodiment, according to which the predetermined touch load is exceeded due to the material insert  15 . Thus, plural recesses  19   a ,  19   b  are disposed within the material insert  15  for the precise adjustment of the touch load. These can be disposed at regular distances relative to each other or at positions that can be predetermined in an arbitrary manner. The depth and/or diameter of the recesses  19   a ,  19   b  can be identical or different. 
         [0054]      FIG. 8  shows a further embodiment, according to which the front end of the key body  2  is completely formed of a material  15 , which is different to the softwood material. According to  FIG. 8 , the block  15  is joined with the key body  2  using a dovetail-connection  21 . As an alternative, arbitrary toothings, gluing or adhesive bonding or so-called shifting connections are used. 
         [0055]    In the following we refer to  FIG. 9  for the manufacturing of a key according to the present invention. According to  FIG. 9 , firstly a rectangular plate  25  is formed of a suitable softwood material. The section-shape of this softwood plate  25  can already be matched with the section-shape of the key body  2  (see  FIGS. 1 and 2 ). Afterwards, a recess, which extends over the entire width, i.e. extending in x-direction, is formed in the rearside of the softwood plate  25 , e.g. by milling a channel having an appropriate profile. In particular, this channel can be of a rectangular or trapezoidal profile or can have any other profile. A material insert  15  of a corresponding shape or profile and of a different specific weight is engaged with or inserted into the afore-mentioned recess and joined with the softwood material in a suitable manner, preferably by gluing, by means of toothings, dovetail-connections, shifting-connections or combinations of the afore-mentioned joining techniques. In a final step the individual key bodies are cut from the plate  25  by cutting along the y-direction, i.e. perpendicular to the x-direction, e.g. by sawing or laser cutting. 
         [0056]    As will be easily apparent to the person skilled in the art, the afore-mentioned recess may also extend up to the front edge of the softwood plate  25 . As an alternative, a material block  15  of an appropriate cross-section may also be joined with the front face of the softwood plate  25  using appropriate joining techniques, as described above. Preferably, the weight of the aforementioned material insert  15  or of the material block  15  is such in order to impart a touch load to the key which is close to the desired touch load, if said key is pivotably supported in a corresponding mechanism. 
         [0057]    The key according to the present invention is suited for the automatic adjustment of the touch load, because by means of the material insert the touch load of the key can be set close to the desired touch load. For such an automatic method reference is made in the following to  FIG. 10 . Therein, steps S 1  to S 3  refer to the indispensable method steps, whereas steps S 4  to S 8  refer to optional individual or plural method steps to be additionally performed. It is assumed that the key is already installed in a normal mechanism. In step S 1  a weight member having a predetermined weight is put on the key at a predetermined position. The position of the weight member is determined, preferably by an optical or optoelectronic method. For the following explanation it is assumed that the touch load is not yet exceeded due to the material insert, i.e. that an additional adjustment weight is to be engaged with said material insert. 
         [0058]    In step S 2  the falling time and/or falling dynamics of the front end of the key body is determined, preferably by an optical or optoelectronic method. From the falling time and/or falling dynamics of the key body, which has been determined in such a manner, and taking into account the position and weight of the weight member the position and/or weight of the adjustment weight to be inserted into the material insert is computed (step S 3 ). Finally, the adjustment weight is engaged with the material insert at the such determined position, in particular by screwing (step S 7 ). 
         [0059]    Therein, the position of the adjustment weight to be inserted can be marked, e.g. by writing, boring or laser marking a side face of the key body (step S 4 ). Before attaching the adjustment weight, the key body may be retained according to step S 5 , e.g. by means of a grasping arm or by means of manually or automatically adjustable clamping blocks. Afterwards, a pilot hole can be formed in the material insert (step S 6 ). This pilot hole can be formed manually by the technician (for which purpose the afore-mentioned marking is of advantage), but can also be formed automatically. Size and position of the pilot hole are matched to the adjustment weight to be inserted, which has been computed in step S 3 . Afterwards, an adjustment weight having the weight computed in step S 3  is inserted at the position, which was computed in step S 3 , in step S 7 , i.e. into the pilot hole. Finally, the key body is released again in step S 8 . Although not shown in  FIG. 10 , this cycle can be followed up by a further cycle, including determining the touch dynamics of the key body. Afterwards the touch load of the key body can be varied in the further cycle by further adjustment of the adjustment weight, by inserting a further adjustment weight, by replacement of the adjustment and/or by appropriately designing a recess of the material insert. Of course, further cycles may follow up this cycle. Further details of such a method for automatically adjusting the touch load, reference is made to U.S. Pat. No. 5,585,582, the whole contents of which is hereby incorporated by reference. 
         [0060]    As will become apparent to the person skilled in the art, the afore-mentioned aspects according to the present invention can be combined in an arbitrary manner. As will be easily apparent to the person skilled in the art, as an alternative to the purposeful loading of the front end of the key body by means of a material insert having a higher specific weight also a purposeful weight reduction of the front end of the key body by means of a material insert having a smaller specific weight can be used for the adjustment of the touch load of the key close to the desired touch load. As will become apparent to the person skilled in the art, a further more common aspect of the present invention relates to the use of a multi-layer composite wood material, as described above, for manufacturing a key body for acoustic pianos and in particular for grant pianos.