Composite string instrument apparatus and method of making such apparatus

A string instrument, such as a violin, is made of graphite fiber cloth and unidirectional graphite fiber sheets and epoxy resin. The instrument includes a unitary body, including a back, a rib, a neck, and a pegbox, all molded as a single or unitary element. A belly and a soundboard are separately molded of the same material and they are appropriately secured to the body. A string assembly is secured to the body and disposed over the belly. A pair of reinforcing struts are secured to the neck and to the rib. A sound post is disposed between the back and the belly, and a bridge is disposed on the belly, and strings of the string assembly are secured to pegs extending through the pegbox, over the bridge, and to a tail piece. The tail piece is in turn secured to the rib by an end pin remote from the neck.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to string instruments, such as violins and, more 
particularly, to a composite string instrument and a method of making a 
string instrument. 
2. Description of the Prior Art 
The construction of the violin and other string instruments of its family 
has changed very little since the 16th century, when well-known artisans 
such as Stradivari, Guarneri and Amati mastered the craft. Their 
instruments are considered the best for tone, power, beauty and, of 
course, investment. Because they are so rare and so expensive, it is not 
often that a person even gets to hear and see one played. Wooden 
instruments of this type are a thing of beauty, and also a delicate, 
fragile, never-can-be-replaced piece of workmanship. 
The violin itself comprises a soundbox, a neck, a pegbox, and four strings 
stretched tightly over the soundbox. The strings attach to a device at the 
lower end called a tailpiece, extend over a bridge near the center of the 
soundbox, and continue to the tuning pegs within the pegbox at the upper 
or distal end of the instrument. When the string is vibrated by plucking 
or by drawing a bow over it, it induces a vibrational energy through the 
bridge to the top and bottom plates of the soundbox (hereafter called the 
"belly" and the "back"). The vibration of these plates enhances and 
amplifies the vibration initiated at the string, and sound is produced. 
The belly and back are connected around their perimeter by a sidewall 
called the rib, and are additionally connected by a column called a sound 
post. 
Because of the tedious and exacting workmanship involved in the making of 
wooden instruments, there have been numerous attempts to fashion 
instruments out of synthetic materials over the past few decades. The idea 
is that with proper tooling, a consistent, easily manufactured instrument 
might be produced. However, the mass market for such instruments has not 
been attained for various reasons, such as poor sound quality, inferior 
looks, or problems involved in the conjunction of both synthetic and 
natural wood materials together in the same instrument. 
In U.S. Pat. No. 3,699,836 (Glasser), a violin is produced using sheets of 
fiberglass overlaid with a wood paper to simulate the wood look of the 
natural instrument. This instrument design calls for the belly, back, and 
rib to be separate pieces, and incorporates a wooden neck and pegbox. The 
problem with this very typical design for composite instruments is that 
with all these glue joints, the instrument is more difficult to 
manufacture. Also, it has much of the fragile nature that the wooden 
counterparts have. If such an instrument were to be dropped, it would 
likely break at the glue joints. Elimination of as many of these joints as 
possible is thus desirable in the manufacture of composite instruments. 
Also, the preferred medium at this date is graphite fiber within an epoxy 
resin matrix, and Glasser's claims extend only to fiberglass. 
The use of graphite/epoxy materials for musical instruments is taught by 
U.S. Pat. No. 3,880,040 (Kaman). This invention calls for unidirectional 
(all strands of fiber going the same direction) graphite layers on both 
top and bottom faces of a wooden core. The idea is to reduce the thickness 
of the soundboard by using stiffer materials on the outside of the wooden 
core. Such an instrument would then still exhibit the pleasant sound 
derived from a completely wooden instrument, but would also project higher 
frequencies of vibration because of the thinness of the soundboard. 
A disadvantage to such a construction is that over time the wood can 
delaminate from the graphite/epoxy surfaces. Also, as violin makers are 
keenly aware, wood has natural variances within from piece to piece, so 
that a maker could not guarantee consistency of sound from instrument to 
instrument. Finally, the disadvantage noted above in Glasser's work would 
apply here, in that the instrument would still be constructed of several 
pieces that would need to be glued together, and a fragile instrument 
would still be the result. 
In U.S. Pat. No. 4,161,130 (Lieber), a completely synthetic combination of 
both the lower soundboard and sidewalls (ribs) is found. The invention is 
for a bass guitar, and is bowl shaped. Because of the complete synthetic 
nature of the materials, sound control and response to vibration would be 
more consistent. The disadvantage of this invention is that the neck is 
bonded or attached separately to the bowl shaped body, and the instrument 
could easily break at this joint if it were dropped. 
Another method of constructing musical instrument soundboxes is taught by 
U.S. Pat. No. 4,144,793 (Soika and Gene). Rotational molding of plastics 
involves putting a specific amount or "charge" of plastic powder into a 
closed cavity mold, and rotating the mold around two axes while 
concurrently heating the mold to a temperature in which the plastic powder 
will melt. The mold is then cooled while still rotating, and then 
disassembled and the part removed. Soika et al proposes making soundboxes 
for instruments in this manner. The same problem as stated above with this 
construction is that the neck is bonded secondarily, and is a potential 
point of breakage. Also, it is well known that acoustic instrument making 
involves exacting tolerances of the thickness of the soundboards, and 
rotational molding does not attain these standards, and the acoustic 
properties are generally not good. 
Up to this point, the neck of the instrument had not been addressed in 
terms of synthetic materials. The neck of the instrument supports the 
highly tensioned strings, plus the pressure exerted upon the strings by 
the player of the instrument. Wooden necks must be made of hard wood, a 
material of sufficient stiffness to prevent the neck from warping or 
twisting under the high forces exerted by the strings. Since these 
hardwoods are heavy, this added weight extending outward from the player 
makes the instrument harder to play and to hold. For this reason, stiffer 
and lighter weight materials were chosen to make instrument necks, and 
this is taught by U.S. Pat. No. 4,145,948 (Turner). It should be noted 
that claim 3 of Turner's patent calls for "said neck including a pegbox 
section, a neck section and a soundbox section." It is not clear, however, 
from this claim just how this is to be accomplished. For example, there is 
no mention of how to reinforce the neck as it joins the soundbox or the 
pegbox. This reinforcement is necessary to prevent the neck from creeping 
and rotating upward in the direction that the string tension is pulling it 
(a very real problem|). Nor does the wording of this claim specifically 
mention the integral nature of the molding of the instrument. The claim 
refers to the neck, which is only a small part of the instrument as a 
whole. 
In U.S. Pat. No. 4,836,076 (Bernier), we see a plastic instrument with 
reinforcement ribs molded to the internal surfaces of the soundboards, and 
the neck molded integrally with the lower soundboard. The claims call for 
a stiffening rib running axially along the center of the inside of the 
lower soundboard, with a plurality of ribs branching off to the sides from 
this main rib. Although this design displays the integral molding of the 
neck, ribs and lower soundboard to which this discussion is leading, it 
must be pointed out that the claims focus on a particular reinforcement 
rib pattern that is molded in conjunction with the soundboard. This is 
quite a disadvantage to sound production in quality instruments, in that 
these major ribs would provide significant damping or muting of the 
soundboard vibrations. In the violin family, only one such rib is 
required, and that is found in the "bass bar" located on the underneath 
side of the belly, or upper soundboard. What is taught by Bernier is not 
conducive to graphite/epoxy laminates, however. These laminates do not 
require such reinforcement since they are superior in strength to molded 
thermoplastics. 
Other graphite/epoxy constructions of violins continue along the trend set 
forth in the '948 patent, Turner, but use unidirectional materials. These 
are found as sheets laid in specified orientations for the separate 
soundboards, the belly and the back. U.S. Pat. No. 4,955,274 (Stephens) is 
one of these. Again, the design calls for the belly, back and rib to be of 
separate pieces, indicating the necessary glue joints as potential 
breakage points. Also, the neck and pegbox are indicated by the patent as 
being of wood, and as such inherit the various problems associated with 
wooden necks, as taught by Turner. Similar disadvantages appear also in 
U.S. Pat. No. 4,408,516 (John). Not only is the John violin built in the 
manner stated above, but there is no differentiation in the physical shape 
of the belly versus the back. Violin makers for centuries have specific 
contours ascribed to each of these, and they are significantly different. 
Yet another laminate scheme for the belly only is ascribed in U.S. Pat. No. 
5,171,926 (Besnainou et al). It is predicted that the same disadvantages 
associated with the designs of Stephens and John would exist. 
A laminate scheme for guitar manufacture is set forth in U.S. Pat. No. 
4,969,381 (Decker) in which a combination of woven fabric and 
unidirectional sheets are used in the soundboards and sidewalls. This 
combination, along with cotton or silk fabric on the outside, is purported 
to be a synthetic equivalent of wood for acoustic purposes. This is good 
in that the combination of high acoustic damping qualities associated with 
the woven fabric and the low acoustic damping qualities associated with 
the unidirectional sheets gives a good, resonant tone. Decker's scheme, 
however, does not provide for variance in the thickness of the back 
laminate, a detail through which violin makers for many years have 
painstakingly worked. It has been shown by our research that good tone is 
accomplished by a laminate stack of varying shapes and sizes in the back 
portion of the instrument, and that this varies from violin to viola to 
cello to string bass. Additionally, Decker's design incorporates the same 
fragile nature disadvantage found above in Stephens' and John's design. 
For centuries, the accepted method used by violin makers to keep the neck 
from rotating up and forward because of the strings' tension has been to 
place a large wood block inside the soundbox adjacent to the neck. This 
block would be fitted and glued to the upper and lower soundboards and to 
the ribs. Guitar manufacturers perform a similar operation. This block 
would be trimmed as much as possible to keep from damping the soundboard 
vibrations, but not so much that the neck would rotate over time. 
Elimination of this block would be of great help to the acoustical 
properties of the instrument, and a means is found in U.S. Pat. No. 
3,974,730 (Adams, Jr.) Whereby this may be done. 
The '730 Adams patent discloses a guitar bracing system in which struts 
arise from each side of the neck at the place where the sides meet the 
lower soundboard, and angle up to the center of the upper soundboard. 
Variations within the design include adjustability of the struts, and 
various locations for these struts. One of the locations is where the 
struts originate at the base of the neck block, where the block meets the 
lower soundboard, and then terminates at a cross brace underneath the 
upper soundboard. While this is good, a more direct bracing would be 
obtained if the struts could somehow originate at the top of the neck 
block, and the angle downwards toward the lower soundboard. 
In keeping with this idea, U.S. Pat. No. 4,836,077 (Hogue) promotes the 
idea of embedding a wooden dowel at an angle downwards through the neck 
and the neck block. This is aimed more as a repair method for neck blocks 
that were shown to be too weak to prevent neck rotation, than as a 
standard manufacturing method for new violins. The design still relies on 
an accurate glue joint between the block and its faces, which still damps 
the vibrations of the soundboards somewhat. 
SUMMARY OF THE INVENTION 
The invention described and claimed herein comprises a composite stringed 
instrument, illustrated as a violin, in which the body of the violin is 
molded as a single element out of woven cloth, preferably made of graphite 
fibers in epoxy, and a plurality of layers of unidirectional fiber sheets 
bonded to the layer of graphite woven cloth, again by epoxy. Reinforcing 
struts are adhesively secured between the neck and upper corners of the 
stringed instrument body. A belly element is separately molded, and a 
fingerboard is also separately molded, and the belly and fingerboard are 
appropriately secured to the body. A string assembly is then appropriately 
secured to the body and disposed over the belly and over the fingerboard. 
Among the objects of the present invention are the following: 
To provide a new and useful stringed instrument apparatus made of composite 
material; 
To provide a new and useful method of making a stringed instrument; 
To provide a new and useful stringed instrument having a unitary molded 
body; and 
To provide a new and useful method of making a composite stringed 
instrument using woven cloth and unidirectional fiber sheets within epoxy 
resin matrix.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is an exploded perspective view of a stringed instrument 6 embodying 
the present invention, including a body 8, a belly 40, a fingerboard 50, 
and a string assembly 60. The stringed instrument 6 is illustrated as a 
violin. 
FIG. 2 is a view in partial section of a portion of the body 8, and FIG. 3 
is a top plan view of the body 8. FIG. 4 is a longitudinal view in partial 
section of the stringed instrument 6, assembled, but without the string 
assembly 60. FIG. 5 is a view in partial section of a portion of the 
stringed instrument 6. For the following discussion, reference will be 
made in general to FIGS. 1, 2, 3, 4, and 5, and specifically to a 
particular figure as required. 
The stringed instrument apparatus 6 includes a composite body 8 molded in a 
single piece using graphite woven cloth and a plurality of layers of 
unidirectional fiber sheets. The fibrous material is embedded in matrix of 
epoxy resin. The body 8 includes a back 10, a rib 12, a neck 14, and a 
pegbox 16. 
The rib 12 extends upwardly from the back 10. Extending outwardly from the 
rib 12 is the neck 14, and at the outer or distal end of the neck 14 is 
the pegbox 16. The back 10, the rib 12, the neck 14, and the pegbox 16 are 
integrally molded together; they are not separately molded or layed up 
pieces secured together. Rather, they are a single, integral element. 
A belly 40 is shown disposed above the body 8. It, too, is made of similar, 
composite materials, as is the body 8, namely a layer of graphite woven 
cloth and a multiplicity or plurality of layers of unidirectional fiber 
sheets embedded in a matrix of epoxy resin. The fingerboard 50 is shown 
disposed above the body 8 and the belly 40. The fingerboard 50 is of like 
construction. 
All of the various elements are made of the graphite/epoxy composite 
material so that the coefficient of thermal expansion is the same for all 
of the components. This precludes warping or twisting of the instrument in 
temperature extremes, if the instrument should be subject to such 
temperature extremes. 
The rib 12 comprises a perimeter side which extends generally upwardly from 
the back 10. The rib 12 include a pair of upper corners 22 and a pair of 
lower corners 24. The portion of the body between the neck and the upper 
corners 22 is referred to as the upper bout, and the portion of the body 
between the upper corners 22 and the lower corners 24 is referred to as 
the C-bout. The portion of the body below the lower corners 24 is referred 
to as the lower bout. 
Extending outwardly from the rib 12 at the upper end of the instrument 6 is 
the neck 14. The neck 14 is molded as an integral part of the body 8, as 
discussed above. For weight constraints, the neck 14 is preferably a 
hollow, U-shaped channel. This is shown in FIG. 2. 
At the outer portion of the neck 14 is the pegbox 16. The pegbox 16 is, of 
course, integral with the neck 14, and it includes a generally U-shaped 
portion, vertical arm elements of which include a plurality of aligned 
apertures in which are disposed bushings 18. This is best shown in FIG. 5. 
The bushings 18 receive pegs 20. The bushings 18 and the pegs 20 are 
preferably made of a liquid crystal polymer. 
Within the body 8, and extending between the neck at the rib 12 and the 
upper corners 22, is a strut assembly shown in FIGS. 1 and 3 as a pair of 
tubular graphite struts 26. The struts 26 extend generally downwardly from 
the upper portion of the neck 14 to the upper corners 22. The struts 26 
are appropriately secured to the neck 14 and to the rib 12 at the corners 
22 by an appropriate adhesive 28, such as a fiber reinforced resin 
For larger instruments, such as a cello and a string bass, the strut 
assembly includes an additional reinforcing laminate plate. The plate is 
disposed in the neck and extends into the upper portion of the body. The 
struts are molded to the laminate plate. This is shown in dash dot line in 
FIG. 3 and identified by reference numeral 32. 
Extending through the belly 40 are a pair of "f" holes 44, well known and 
understood in stringed instruments, such as violins. Disposed between the 
"f" holes 44, and extending upwardly from the belly 40, is a bridge 46. 
The bridge 46 includes feet 48 which extend downwardly and are disposed on 
the belly 40. The bridge 46 is preferably made of maple wood. The bridge 
is held onto the belly 40 by string tension, as is well known and 
understood. 
As best shown in FIG. 4 a bass bar 42 is shown extending longitudinally on 
the bottom of the belly 40. The bass bar 42 is, of course, integral with 
the belly 40. 
As indicated above, the fingerboard 50 is made of the same material as the 
body 8. That is, the fingerboard 50 is made of graphite woven cloth and a 
plurality of layers of unidirectional graphite fiber sheets in an epoxy 
matrix. 
The fingerboard 50 is appropriately secured to the upper portion of the 
neck 14. This is best shown in FIG. 4. 
The string assembly 60 is shown in FIG. 1 disposed above the fingerboard 
50, the bridge 48, and the belly 40. The string assembly 60 includes four 
strings 62 and a tail piece 64. The strings 62 are secured to one end of 
the tail piece 64 and extend outwardly therefrom. The outer ends of the 
strings, remote from the tail piece 64, are secured to the pegs 20 for 
tuning the strings. At the lower or bottom end of the tail piece 64, 
remote from the strings 62, is a tail piece adjustor loop 66. The tail 
piece adjustor loop 66 is secured to the lower or bottom end of the rib 12 
of the body 8 by means of an end pin 68. The end pin 68 extends through 
the rib 12 and into a block 30. The block 30 is also an integral part of 
the body 8. 
As is well known and understood, the strings 62 are appropriately tuned by 
rotating the pegs 20 in the bushings 18 of the pegbox 16. 
A soundpost 36, which is a hollow graphite cylinder, is disposed between 
the back 10 and the belly 40. The purpose of the soundpost 36 is to 
transmit vibrations made by the strings between the belly 40 and the back 
10. 
The construction of the stringed instrument 6 is illustrated in FIG. 6, 
which comprises a perspective view showing three layers of materials 
disposed one on top of the other. The bottom layer comprises a layer of 
graphite woven cloth 70. Disposed on top of the graphite woven cloth layer 
70 is a sheet of unidirectional graphite fiber 72. On top of the 
unidirectional fiber sheet 72 is a second unidirectional fiber sheet layer 
74. The direction of the fibers in the sheets 72 and 74 are slightly 
angularly oriented relative to each other. That is, the fiber directions 
in the respective sheets 72 and 74 are close to parallel. The fiber 
orientations closely emulate the spruce modulus. 
There may be additional layers of unidirectional fiber sheets on top of 
those illustrated in FIG. 6, as required. As indicated above, the 
thickness of the body 8 and of the belly 40 are different, and accordingly 
a different number of layers are found in the body 8 from the belly 40. 
While the principles of the invention have been made clear in illustrative 
embodiments, there will be immediately obvious to those skilled in the art 
many modifications of structure, arrangement, proportions, the elements, 
materials, and components used in the practice of the invention, and 
otherwise, which are particularly adapted to specific environments and 
operative requirements without departing from those principles. The 
appended claims are intended to cover and embrace any and all such 
modifications, within the limits only of the true spirit and scope of the 
invention.