Abstract:
A method of producing and assembling carbon composite based stringed musical instruments. The assembled stringed musical instrument is relatively inexpensive, extremely sturdy, light weight and simulates tones as deep and resonant as obtained by any other wood based instruments. The method also provides for manufacturing geometrically identical stringed musical instruments and the method being adaptable for producing and assembling any stringed musical instrument.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims an invention which was disclosed in Provisional Application No. 62/340,190, filed May 23, 2016, entitled “Apparatus and Methods for Carbon Composite Stringed Musical Instruments”. The benefit under 35 U.S.C. §119(e) of the U.S. provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The inventive subject matter relates to carbon composite components. More particularly the inventive subject matter pertains to stringed musical instruments made of layers of carbon fiber and resin with a core and base layer of specific material, and methods of making such components. 
       BACKGROUND 
       [0003]    Carbon fiber composites have been put to use in many applications for decades including musical instruments. Carbon fiber has a high stiffness to mass ratio and the manufacturing process lending itself well to shell structures. Therefore, carbon fiber composites are an obvious choice for an alternative to wood components in stringed instruments. 
         [0004]    Carbon fiber, being a good substitute for wood, has several advantages. Carbon composites based instruments allow for manufacturing instruments with specific properties which can be made repeatable in all the manufactured pieces. Carbon composite based musical instruments are not subject to dimensional variation from changing temperature and humidity, unlike wood based instruments which are very sensitive to environmental changes. Also, the carbon composite instruments are light weight and stronger, making them easier to transport and are much less likely to be damaged during shipping. Finally, composite based musical instruments avoid using endangered species of wood that are becoming more difficult to find. 
         [0005]    Several examples of stringed instruments not made from wood and including carbon fiber are: 
         [0006]    U.S. Pat No. 3,699,836 issued to Glasser describes a violin constructed from resin. U.S. Pat No. 3,880,040 issued to Kaman describes a guitar having a sound board made of layers of graphite fiber and a wood core. U.S. Pat No. 4,334,452 issued to Morrison describes a plastic musical instrument body having a structural insert. U.S. Pat No. 4,313,362 issued to Lieber describes an electric guitar with plastic construction. U.S. Pat No. 4,348,933 issued to Kaman et al. describes a sound board assembly made of carbon composites for use in a piano or the like. U.S. Pat No. 4,364,990 issued to Haines describes a construction material for stringed musical instruments using card board or paper core covered in carbon fiber material. U.S. Pat No. 4,873,907 and U.S. Pat No. 4,969,381 issued to Decker Jr. et al describe composite materials acoustic stringed musical instrument. 
         [0007]    Accordingly, there remains a continual need for improved apparatus and methods for a construction of stringed musical instrument with carbon composite as a base. Additionally, it would be desirous if the same fine-tuning control can be achieved in the carbon composite based musical instruments as any other traditional wood based stringed musical instrument. It is to these and other improvements that preferred embodiments of the present inventive subject matter are generally directed. 
       SUMMARY 
       [0008]    An object of the present inventive subject matter in one of the embodiments is to describe a stringed musical instrument made from carbon composite material. Another object of the present inventive subject matter is to provide a method for producing most of the components of the stringed musical instrument based on carbon composite materials. Still another object of the present inventive subject matter is to provide a method for assembling the components of the stringed musical instrument based on carbon composite materials. In another object of the inventive subject matter is to provide a method for assembling a stringed musical instrument made from carbon composite material is described. Yet another object of the inventive subject matter is to provide a relatively inexpensive stringed musical instrument based on carbon composite components which simulates tones as deep and resonant as obtained by other wood based instruments. Yet another object of the inventive subject matter is to provide a stringed musical instrument which is substantially stronger than a wood based musical instrument. In still yet another object of the inventive subject matter is to provide a method for manufacturing geometrically identical stringed musical instrument which is substantially stronger than a wood based musical instrument and also the method being adaptable for any kind of string musical instrument. These and other embodiments are described in more detail in the following detailed descriptions and the figures. The foregoing is not intended to be an exhaustive list of embodiments and features of the present inventive subject matter. Persons skilled in the art are capable of appreciating other embodiments and features from the following detailed description in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A : Pictorial illustrations of the steps involved in cutting and kitting prepreg and foam. 
           [0010]      FIG. 1B : Pictorial illustrations of the steps involved in cutting and kitting prepreg and foam. 
           [0011]      FIG. 1C : Pictorial illustrations of the steps involved in cutting and kitting prepreg and foam. 
           [0012]      FIG. 1D : Pictorial illustrations of the steps involved in cutting and kitting prepreg and foam. 
           [0013]      FIG. 2 : Illustrates Process Flow chart. 
           [0014]      FIG. 2A : Pictorial illustrations of the steps involved in preform. 
           [0015]      FIG. 2B : Pictorial illustrations of the steps involved in preform. 
           [0016]      FIG. 2C : Pictorial illustrations of the steps involved in preform. 
           [0017]      FIG. 2D : Pictorial illustrations of the steps involved in preform. 
           [0018]      FIG. 2E : Pictorial illustrations of the steps involved in preform. 
           [0019]      FIG. 2F : Pictorial illustrations of the steps involved in preform. 
           [0020]      FIG. 2G : Pictorial illustrations of the steps involved in preform. 
           [0021]      FIG. 2H : Pictorial illustrations of the steps involved in preform. 
           [0022]      FIG. 2I : Pictorial illustrations of the steps involved in preform. 
           [0023]      FIG. 2J : Pictorial illustrations of the steps involved in preform. 
           [0024]      FIG. 2K : Pictorial illustrations of the steps involved in preform. 
           [0025]      FIG. 2L : Pictorial illustrations of the steps involved in preform. 
           [0026]      FIG. 2M : Pictorial illustrations of the steps involved in preform. 
           [0027]      FIG. 3A : Pictorial illustrations of the steps involved in assembling of bass bar. 
           [0028]      FIG. 3B : Pictorial illustrations of the steps involved in assembling of bass bar. 
           [0029]      FIG. 3C : Pictorial illustrations of the steps involved in assembling of bass bar. 
           [0030]      FIG. 4A : Pictorial illustrations of the steps involved in assembling of a neck component. 
           [0031]      FIG. 4B : Pictorial illustrations of the steps involved in assembling of a neck component. 
           [0032]      FIG. 4C : Pictorial illustrations of the steps involved in assembling of a neck component. 
           [0033]      FIG. 5A : Pictorial illustrations of the steps involved in assembling of a top and bottom plates. 
           [0034]      FIG. 5B : Pictorial illustrations of the steps involved in assembling of a top and bottom plates. 
           [0035]      FIG. 5C : Pictorial illustrations of the steps involved in assembling of a top and bottom plates. 
           [0036]      FIG. 5D : Pictorial illustrations of the steps involved in assembling of a top and bottom plates. 
       
    
    
     LIST OF SELECTED REFERENCE CHARACTERS 
       [0000]    
       
           110 - 142 : Represents the components and steps associated with prepreg foam. 
           200 A- 200 M: Represents the steps associated with preform. 
           205 - 266 : Represents the components and steps associated with preform. 
           310 - 330 : Represents the components and steps associated with assembling of bass bar. 
           410 - 431 : Represents the components and steps associated with assembling of a neck component. 
           510 - 541 : Represents the components and steps associated with assembling of a top and bottom plates. 
       
     
       DETAILED DESCRIPTION 
       [0043]    The present inventive subject matter is shown in reference for manufacturing a violin. Other stringed musical instruments such as a viola, cello, bass, guitar, sitar and the like may be beneficially produced and assembled in accordance with the principles of the inventive subject matter. 
         [0044]    Carbon fiber is made from a common industrial fiber called polyacrylonitrile fiber. These fibers are woven into fabric with various weave patterns. The inventive subject matter described herein uses 3K carbon fiber fabrics (3000 filaments per fiber). Carbon fiber is further pre-impregnated with epoxy and is called “pre-preg”. The pre-preg used is unidirectional, meaning it has been spread out onto backing paper. The core mainly constitutes a low density expandable epoxy foam. 
         [0045]    The different steps involved in the method for (i) making the different components, (ii) assembling and (iii) setting up the stringed musical instrument are as described below with particular reference to the making of a violin. Other stringed musical instruments such as a viola, cello, bass, guitar, sitar and the like may be beneficially produced and assembled in accordance with the principles of the inventive subject matter. 
         [0046]    The first step involves cutting and kitting of prepreg and foam. An improved cutting accuracy reduces the number of design changes that would be required at the production facility because of cutting errors. At this stage, itself one has to evaluate trim cover designs while they are being prototyped and make sure that the parts will be identical in production. This mainly helps in saving time to cut the porotypes in identical shapes and measurements. In a preferred embodiment, the cutting process may be atomized by using computer based cutting technology like Auto Metrix instruments. 
         [0047]    The expandable foam is stored in a freezer prior to use and thawed for 20-25 minutes before preparing the foam for cutting purposes. The 4/4 mold is measured for its height and breadth and an expandable foam sheet is prepared to be cut accordingly. 
         [0048]    A rectangular piece of the expandable foam material  111  is cut and placed on the bottom plate of the 4/4 aluminum mold  112  followed by the top plate  113  and the whole set up is cured so as to get a definite impression of the outline of the body of the violin including the outer and inner outlines as shown in  110  of  FIG. 1A . The expandable foam material is cut on the outer out line  121  as shown in  120  of  FIG. 1B  and the inner outline  131  as shown in  130  of  FIG. 1C . The strip cutout  141  is separated from the body piece cutout  142  of the violin as shown in  140  of  FIG. 1D . 
         [0049]    Referring to  FIG. 2-2M, 200-265  illustrate the flow chart and the pictorial representation of the processes involved in preform. As shown in  205  of  FIG. 2A , an aluminum mold  204 , an outside layer of carbon fiber fabric  206  (hereafter 3K), one inside layer of 3K  207 , a strip  208  and the body cutouts of the expandable foam  209 , all of them having the outline shape of the body of the violin are organized at a place for further use (step  200 A of  FIG. 2 ). Eight small tabs of 1.0 cm,  211  from the perimeter of the inside layer of 3K  207  is cut (step  200 B of  FIG. 2 ) as shown in  210  of  FIG. 2B . The red plastic protection cover  216  on the outside layer of 3K  206  is removed (step  200 C of  FIG. 2 ) as shown in  215  of  FIG. 2C . The outside layer of 3K,  206  with the most resin content is placed on top of the 4/4 aluminum mold  204  (step  200 D of  FIG. 2 ) as shown in  220  of  FIG. 2D . The outside layer of 3K  206  is warmed with hands using gloves to manually adjust it to the shape of the mold  204  (step  200 E of  FIG. 2 ) as shown in  225  of  FIG. 2E . The protective cover papers  231  on both sides of the expandable foam  209  are removed (step  200 F of FIG.  2 ) as shown in  230  of  FIG. 2F . The expandable foam layer  209  is put in the center of the outside layer of 3K  206  placed on the aluminum mold  204  ( 200 G of  FIG. 2 ) as shown in  235  of  FIG. 2G . The strip of the expandable foam  208  cut earlier is placed on the edge  241  of the mold  204  (step  200 H of  FIG. 2 ) as shown in  240  of  FIG. 2H . The edges of the outside layer of 3K  206  and the foam  209  are all manually adjusted to accommodate all the layers (step  200 I of  FIG. 2 ) as shown in  245  of  FIG. 2I . The red plastic protection cover  251  of the inside layer of 3K  207  is removed (step  200 J of  FIG. 2 ) as shown in  250  of  FIG. 2J . The inside layer of 3K  207  is placed on the top of the expandable foam layer  206  (step  200 K of  FIG. 2 ) as shown in  255  of  FIG. 2K . All the layers are manually adjusted to accommodate each other in place (step  200 L of  FIG. 2 ) to get to an arrangement on the mold  204  as shown in  260  of  FIG. 2L . A red label  266  with the code for a violin like image is placed on the top of the inside layer of 3K  207  (step  200 M of  FIG. 2 ), thus marking that the whole setup is for making a violin as shown in  265  of  FIG. 2M . 
         [0050]    The second step involves compression molding of plates and ribs. This is a method of molding in which the molding material, generally preheated, is first placed in an open, heated 4/4 aluminum mold cavity. The mold is closed with a top plate of the 4/4 aluminum mold, pressure is applied to force the material into contact with all mold areas, while heat and pressure are maintained until the molding material has cured. The advantage of compression molding is its ability to mold large, fairly intricate parts. In a preferred embodiment, the compression molding step is executed in a temperature range of 270 to 280-degree F. for time period ranging between 2.4-2.6 hours. 
         [0051]    Also, it is one of the lowest cost molding methods compared with other methods such as transfer molding and injection molding; moreover it wastes relatively little material, giving it an advantage when working with expensive compounds. Compression molding is a forming process in which a plastic material is placed directly into a heated metal mold, then is softened by the heat, and forced to conform to the shape of the mold as the mold closes. The different mete s for achieving the best results are using the proper amount of material, minimum amount of energy required for heating, minimum amount of time required for heating, appropriate heating techniques, and designing a proper rapid cooling after the material has been compressed into the mold. 
         [0052]    The third step involves injection molding some of the components of the stringed musical instrument. The present inventive subject matter describes the usage of 50% carbon filled resins for injection molding some of the components of the stringed musical instrument. The different components being namely, top plate, back plate, ribs, neck, fingerboard, end button, neck block, end block, corner blocks, bass bar, sound post, bridge pegs and tailpiece are molded using injection molding. In a preferred embodiment, the compression molding step is executed in a temperature range of 300-450-degree F. for time period ranging between 1.0-6.0 minutes. 
         [0053]    The fourth step involves computer numerical control (CNC) operations, which basically streamlines all the cutting processes that are to be carried out and all the final dimensions are fed into a computer via a program. The computer carries out all the cutting processes. The main purpose of the CNC operations is to trim some of the cured composite at the edges of the desired shapes, so as to give it proper desired shape such as round, rectangular, etc. The computer directs the machine tool to perform various machining operations as per the program of instructions fed. 
         [0054]    The fifth step involves sanding and painting to give a final finish to the stringed musical instrument. The purpose of sanding is to remove imperfections and machine marks which effect the finish of the stringed musical instrument. It is desirable to always sand the sand paper with the grain and not against it. For flat and level surfaces a non-flexible sanding block can be used and for contours a flexible sanding block is used. At least three grades namely rough, medium and fine of sandpaper is used prior to painting. Once a smooth surface is obtained a primer is applied followed by the application of a desired colored paint in several coats to achieve a shiny finish. 
         [0055]    The sixth step involves to assemble the component parts produced by the above described methods. 
         [0056]    Referring to  FIG. 3A-3C, 310-330  illustrates the bass bar is assembly on to the inside of the bottom plate of the violin. Firstly, the bottom plate  311  and the bass bar  312  is organized at a place as shown in  310  of  FIG. 3A . An epoxy adhesive  322  is uniformly applied to the bottom surface  321  of the bass bar as shown in  320  of  FIG. 3B . The bass bar having the epoxy adhesive on the bottom surface is faced down and placed manually on the inside layer of the bottom plate and pressed firmly to secure in its position as shown in  330  of  FIG. 3C . 
         [0057]    Referring to  FIG. 4A-4C, 410-430  illustrates an assembly of neck attachment to the bottom plate of the violin. Firstly, all the components to be assembled is placed at a place as shown in  410  of  FIG. 4A , namely, the bottom plate  311 , the top plate  411 , the joints and bolts  412  and  413  and the neck attachment  414 . As shown in  FIG. 4B, 420  illustrates the attachment of joints  412  with an epoxy adhesive  322 . The base of the joints  412  is prepared for receiving the neck attachment by applying the epoxy adhesive  322 . The neck attachment  414  is firmly attached to the bottom plate with the help of joints  412  and bolts  441  as shown in  430  of  FIG. 4C   
         [0058]    The body of the stringed musical instrument is assembled using CNC machined grooves and pockets to accept ribs and tabs on blocks. A unique body unit construction is described herein. Firstly, the bottom plate and the top plate are organized at a place as shown in  510  of  FIG. 5A . Epoxy adhesive is uniformly applied to the edges of the inner layer of the top plate  411  as shown in  520  of  FIG. 5B . The top plate  411  with the adhesive edging is faced down and placed on the bottom plate as shown in  530  of  FIG. 5C . Clamps  541  are fixed on the outer edges of the fixed body unit to hold on the top  411  and bottom plates  311  firmly in place as shown in  540  of  FIG. 5D . 
         [0059]    The last step involves to give a finishing touch by setting up the assembled musical stringed instrument as described above. The process of setting up may be achieved by implementing the following steps in the given sequence: (a) adjust the Truss Rod (b) adjust the Bridge Height (c) check the Nut Height (d) check the Electronics (e) change the Strings (f) check the Tuning Machine Hardware (g) clean and Polish the Frets (h) clean and Oil the Fretboard (i) inspect for Structural Problems (j) adjust the Pickup Height (k) set the Intonation (l) clean and polish. 
         [0060]    The other advantage of the present inventive subject matter is the production of stringed musical instruments which are relatively inexpensive, extremely sturdy and of light weight which would help in easy handling of the instrument when played. 
         [0061]    It is a primary object of the inventive subject matter to describe a method of making stringed musical instruments which are geometrically identical thus eliminating the fine hand-crafted skills required for carving and constructing a stringed musical instrument. It will be appreciated that when the stringed musical instruments are made identical then one can achieve identical tone characteristics too. 
         [0062]    The many aspects and benefits of the invention are apparent from the detailed description, and thus, it is intended for the following claims to cover all such aspects and benefits of the invention which fall within the scope and spirit of the invention. In addition, because numerous modifications and variations will be obvious and readily occur to those skilled in the art, the claims should not be construed to limit the invention to the exact construction and operation illustrated and described herein. Accordingly, all suitable modifications and equivalents should be understood to fall within the scope of the invention as claimed herein.