Linear dovetail neck joint for musical instruments

Abstract

A linear dovetail neck joint for a musical instrument having a neck, a body, and a fretboard. The linear dovetail neck joint relies on an internal dovetail with screw-adjustable tension while avoiding screws that enter directly into the neck. The linear dovetail neck joint allows for excellent fret access in the upper register of the fretboard (due to no heel on the neck), easier adjustment of neck height, intonation correction, and a unique front block construction with hand-shaped undulations - all without the need for adhesives. The linear dovetail neck joint allows for a practical and aesthetically pleasing neck-to-body joint without a heel on the neck. As a result, the neck-to-body joint is easily adjustable and easily repairable.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Patent Application No. 16 / 796,010, filed Feb. 20, 2020, which in turn claims the benefit of U.S. Provisional Patent No. 62 / 864,770, filed Jun. 21, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to neck joints in stringed instruments such as guitars, and more particularly, to a neck joint that facilitates linear and angular adjustment between a neck and a body connected by the neck joint. Background Art

[0004] Music plays an important role in our daily lives and is incorporated into the fabric of society. Many people play music as a pastime, hobby, or profession. As a major branch of musical instruments, chordophones are instruments that produce sound by one or more vibrating strings stretched between two points. Chordophones, especially stringed instruments, are very popular worldwide because they are versatile and suitable for different types of music. The most popular stringed instrument is probably the modern guitar, including the acoustic guitar that projects sound acoustically and the electric guitar that projects sound through electronic amplification. Conventional acoustic and electric guitars include a body and a neck attached to the body via a joint, with one or more elongated flexible strings extending along a fretboard between the body and the distal end of the neck. (The terms "distal" or "distal end" are used to define the part or surface of an element that is furthest from the user.)

[0005] There are three general types of neck joints in stringed instruments. "Neck-through" instruments have a neck that runs completely through the instrument and is almost always permanently glued in place. "Set-neck" instruments have a neck that is also permanently glued in place, with a mortise or dovetail joint where the body and the neck meet. These instruments typically have a neck heel that is just in front of the body and extends down to the back of the body for support. Finally, there are "bolt-on" instruments (actually, threaded attachment is more accurate), which have openings at the location where the neck overlaps the body in the body and where the bolts (or screws) that join the neck to the body are located. Generally, in this type of instrument, the neck joint is made solid so that there is no movement between the neck and the body during use of the instrument. However, the bolts can be loosened so that the neck can be removed from or repositioned on the body.

[0006] Traditionally, an acoustic guitar is a neck-through instrument where the neck heel is positioned just in front of the body and extends down to the rear of the body. This forward protrusion of the neck adjacent to the body below limits access to the highest areas of the fretboard during play. Electric guitars are typically either neck-through or bolt-on instruments. A common bolt-on instrument is economical to construct and repair. A drawback of existing bolt-on designs is that the side-to-side rigidity of the joint is less than that of a glued neck, and access to the highest areas of the fretboard near the body in the front is restricted by the body portion extending below the neck overlap. Given the drawbacks of bolt-on designs, most conventional acoustic and electric guitars permanently attach the neck to the body of the guitar during the manufacture and assembly of the guitar. A common drawback of this permanent attachment mechanism is that the neck cannot be easily displaced from the body to facilitate adjustment of the guitar's characteristics.

[0007] As is well known in the art, the main quality characteristics of a guitar are tone (i.e., the auditory properties of the instrument, including volume, brightness, evenness, note separation, etc.), playability (i.e., the responsiveness of the instrument to the player's technique), and sustain or note duration (i.e., the ability of the instrument to transmit tone and playability over several years or decades). The neck joint is important for all three of these guitar characteristics. A brief discussion of how the neck joint affects the tone, sustain, and playability characteristics of a guitar follows.

[0008] Regarding tone, the transmission of vibration is crucial to the tone or sound of a guitar. The intersection where the neck and body meet (i.e., the neck joint) forms a kind of "acoustic crossroads". Thus, the neck joint is an important part of the sound transmission pattern in a guitar, where high, low, mid, fundamental, and all forms of harmonic decisions are made as to whether to take the off-ramp or choose to exit via the off-ramp. Depending on the type of neck joint, the result of this physically driven filtering system largely defines the tone of the guitar.

[0009] The term "sustain" is intended to represent a measure of how a musical sound changes over time. More specifically, sustain refers to the length of time that the sound of a guitar persists until it is inaudible. The sustain of a guitar is diminished by the conventional mechanisms used to attach the guitar neck to the body. Generally, the stronger the mechanical connection rigidity between the neck and body of a guitar, the longer the sustain of the guitar. Additionally, a rigid mechanical connection between the neck and body of a guitar typically improves the quality and consistency of the musical sound produced by the guitar. Thus, it is desirable to provide a substantially rigid mechanical connection between the neck and body of a guitar. This desire also explains why most guitars manufactured today continue to be constructed with a neck that fits tightly and is glued to the guitar body (i.e., neck-through guitars).

[0010] Finally, consider playability. For the playability of stringed instruments, it is important the distance the strings are located above the neck. The height of the strings relative to the neck and fretboard is commonly referred to as the "action" of the strings. Generally, the desired action on a guitar depends on the individual preference of each user. Some musicians prefer a smaller distance or "low" action between the fretboard and the strings, while others require a high action. If the action is too high, it is difficult and unpleasant to play, and in extreme cases, can cause repetitive stress injuries. If the action is too low, the strings will "buzz" on the frets, or may actually stay on the frets, rendering the instrument largely unplayable. Generally, small differences in the height of the strings above the neck can have a significant impact on the playing of both amateur and professional musicians. The acceptable range of action is small - perhaps around 2.5 millimeters (0.1 inches).

[0011] Given this small range, guitars must be manufactured very precisely with respect to their neck joints and must maintain this critical geometry under the stress of string tensions up to 180 pounds. On traditional guitars, the action of the instrument is typically set at the factory and changes to the action must be done by an experienced technician. Additionally, traditional guitars generally have a very limited range of movement and significant changes to the action of the instrument may only be achievable by modifying the structure of the body or neck of the instrument. These types of modifications can be quite expensive and may have a serious impact on the long-term performance of the guitar. Accordingly, there is a desire for an instrument that allows a user to quickly and efficiently adjust the action on the instrument.

[0012] Several known stringed instruments change the action of the instrument by adjusting the angle at which the neck extends from the guitar body. These instruments rely on the principle that when the angle between the neck and the body increases, the action decreases, and when the angle decreases, the action increases. This action can be increased or decreased by adjusting the angle between the neck and the body of the guitar. However, changing the angle of the neck relative to the body also affects the intonation, tonal properties, and scale length of the guitar strings. A disadvantage of these designs is that the user cannot adjust the action of the neck without changing the intonation and sound of the guitar.

[0013] For example, U.S. Patent No. 6,051,766 discloses a guitar in which the angle of the neck relative to the guitar body is changed by placing shims of different widths into the guitar cavity at the location where the neck is fixed to the guitar body. U.S. Patent No. 6,265,648 discloses another adjustable neck that provides a neck fixed to the guitar body via a spring-loaded clamping device, where the clamping device creates a pivot point that allows the neck to move at an angle relative to the body. Neither of these devices allows a user to adjust the linear direction of the neck without changing the angle of the neck relative to the body. Additionally, the '766 patent requires the user to remove the neck from the guitar body in order to adjust the action of the guitar strings. Further, the '648 patent relies on the biasing force of a spring to hold the neck in place. This spring force can degrade over time, making the neck unstable. The force provided by the spring also creates an upward force at the joint between the neck and the body, which can cause damage to various components of the guitar. Accordingly, there is a desire for a neck that can also be easily adjusted in a linear direction without affecting the angle at which the neck extends from the body.

[0014] Rigid guitar structures are generally too heavy and may be detrimental to tone. Lighter guitar structures tend to sound better, but there is a risk that over time, the neck may eventually be pulled up, thereby changing the action of the strings to an extent that the neck must ultimately be reset, which typically requires an expensive repair costing hundreds of dollars. Thus, the tone, playability, and durability or sustain of a guitar are substantially conflicting and often require trade-offs in design. Some luthiers believe that a balance of these three characteristics is more desirable.

[0015] Even after a luthier has completed the construction of a guitar, a user may want to change the characteristics of the guitar. For various reasons, musicians often desire to use guitars with different characteristics. The ease and comfort of playing, as well as the tone or sound produced by the guitar, are highly dependent on the characteristics of the neck joint. Currently, the only practical way to change the characteristics of a guitar is to use another guitar with a different construction (including neck joint type). In addition to the cost, using multiple guitars with different constructions exacerbates storage and transportation issues.

[0016] Most guitars are made of wood, and wood tends to move over time under the tension of the strings and in response to daily humidity changes. For example, a guitar with a comfortable low action in Houston, Texas, might shrink to an almost unplayable state if flown to Minneapolis, Minnesota, in the winter. Luthiers must anticipate that a guitar may spend time in a low-humidity environment, so stringed instruments must have a high enough action to remain playable in all foreseeable circumstances. Unfortunately, when the humidity is high, the action will usually be suboptimal.

[0017] Consequently, guitars generally tend to have a higher action than desired to allow for the possibility that the stringed instrument will eventually experience a low-humidity environment. Over time, the string tension gradually deforms the wooden structure, and this action may increase and gradually get worse. Modifying the action of a stringed instrument is often hampered for musicians, owners, technicians, or restorers because many guitars have a fixed neck, which limits the range of any relatively easy adjustment of the action.

[0018] One scheme for attempting to modify the action of a guitar with a fixed neck is to take the strings off the guitar and then remove and plane down the saddle. Since the height of the saddle is usually small, the saddle must be planed down significantly in order to have any real effect on the action. Additionally, the adjustment of the saddle height may only temporarily solve the problem. Moreover, a short saddle tends to reduce the leverage that the strings have to vibrate the top surface of the guitar body, so the tone and volume of the guitar are usually affected to some degree.

[0019] More often, musicians, owners, technicians, or restorers will attempt to adjust the truss rod. The truss rod generally consists of a threaded rod with the nut located at each end, and the truss rod extends parallel to another rod or bar. By rotating the threaded rod in one direction or the other, the truss rod eventually begins to bend, causing the neck and associated fretboard to bend correspondingly. It should be understood that using the truss rod to compensate for more than a minor undulation is generally a poor choice because such an adjustment often causes the truss rod to break, and this usually results in the guitar ultimately being discarded by the owner.

[0020] Some luthiers have incorporated various mechanisms to adjust the geometry of the neck joint. Over a century ago, they experimented with adjustable neck joints. Today, many luthiers use neck joints that can be adjusted in one way or another. However, given their drawbacks, only a small percentage of all guitars have such a neck adjustment system.

[0021] The most common solution is to enable the headstock end of the neck to be slightly "tilted" relative to the body, e.g., pivot at the point where the neck root contacts the body. This pivoting is controlled by a screw that extends through the neck root deep into the body well below the pivot point. Rotation of the screw in one direction pushes the root further away from the body and effectively pushes the headstock backward, thereby reducing the distance from the strings to the fretboard and lowering the string height. U.S. Patent No. 7,157,634 discloses an example of such a solution. Since the pivot point is well below the plane of the strings, this tilt also increases the distance between the nut and the bridge. The adjustment mechanism must exert a considerable force because the strings are already under a tension of approximately 180 pounds, so for safety, it may be necessary to loosen the strings of the guitar before attempting an adjustment. In any case, any stretching or relaxation of the strings will change the pitch of the strings, thus requiring the player to retune the guitar after the adjustment. It should be understood that significant adjustments are sufficient to change the distance between the nut and the bridge such that the new effective scale length no longer matches the layout of the frets, and the instrument may sound out of tune. To make the most effective use of this principle, the manufacturer must set the adjustable range in the middle of its potential travel to allow for two-way adjustment.

[0022] Another solution is to use, for example, a sliding mortise and tenon joint to raise and lower the entire neck relative to the guitar body. Such a system is described in U.S. Patent No. 7,557,281, but other "elevator" systems are also available and are known in the art. For a given change in string height, the elevator system generally also stretches or relaxes the strings, but usually less than the tilt system discussed above. However, even if the direction of travel is very close to being precisely perpendicular to the plane of the strings, some stretching or slackening of the strings generally occurs as a geometric issue, which changes the pitch of the strings.

[0023] Although the neck and body portions have been formed as a single one-piece unit, a variety of guitars have been manufactured in which the neck and body portions are formed from separate parts that are attached together to form the instrument. Many neck and body attachments are known in the prior art. Each of the existing attachments has various problems. Among other things, the existing attachments may be difficult to assemble, costly to assemble, structurally unsound, and aesthetically undesirable. Accordingly, there is a continuing need in the art for improved neck and body attachment methods and devices. There is a particular need for a highly practical and mass-producible neck mounting or joint mechanism that allows for simple adjustment of the neck position within the plane of the body surface. Summary of the Invention

[0024] To meet these and other needs and to overcome the disadvantages of existing neck joints, a linear dovetail neck joint for musical instruments is provided. An object of the present disclosure is to facilitate quick and convenient adjustment of the relative height and angle of the neck relative to the body of a stringed instrument such that a user or musician can easily modify the string action and intonation. A related object is to obtain a neck that can be easily adjusted in a linear direction without affecting the angle at which the neck extends from the body. Another object of the present disclosure is to provide a neck joint that secures the neck to the body with a rigid mechanical connection. Another object is to provide a neck joint that does not adversely affect the tone or sound, playability, or sustain of the musical instrument.

[0025] To achieve these and other objects and in view of its objectives, the present disclosure provides a linear dovetail neck joint for musical instruments having a neck, a body, and a fingerboard. The linear dovetail neck joint relies on an internal dovetail with screw-adjustable tension while avoiding screws that go directly into the neck. The linear dovetail neck joint allows for excellent fret accessibility in the upper register of the fingerboard (since there is no heel on the neck), easier neck height adjustment, intonation correction, and a unique front block construction with hand relief - all without the need for adhesives. The linear dovetail neck joint allows for a practical and aesthetically pleasing neck-to-body joint without the need for a heel on the neck. As a result, a neck-to-body joint that is easily adjustable and easily repairable is formed.

[0026] More specifically, a linear dovetail neck joint for a musical instrument includes a neck having a bottom surface with a mortise. A block has a contoured surface, a top platform, and a rear surface, wherein the contoured surface forms part of the body of the musical instrument when the block is fastened to the body, the top platform has a hole that is accessible from outside the musical instrument and is configured to receive a fastener, and the rear surface has a window. A spacer sleeve is configured to be inserted into the window in the rear surface of the block. At least one substantially flat spacer is configured to be inserted into the spacer sleeve, the spacer having a top portion whose height, when the linear dovetail neck joint is fully assembled, defines the distance by which the linear dovetail neck joint separates the neck from the block when the bottom surface of the neck rests on the top portion of the spacer. A dovetail key at least indirectly engages the mortise of the neck and has a top, a bottom, and an opening extending from the top through the dovetail key to the bottom. The opening is aligned with the hole in the block and is configured to receive a fastener. Rotation of the fastener in the opening causes the fastener to pull the dovetail key, along with the neck, downward toward the top platform of the block and attach the dovetail key and the neck to the block.

[0027] More specifically, the linear dovetail neck joint has two main components: a modified neck and a block with a contoured surface that forms part of the body when the block is fastened to the body. The intonation set screw moves the neck relative to the body and adjusts the intonation of the instrument. The neck has a top surface and a bottom surface, where the top surface has a channel configured to receive a truss rod, and the bottom surface has a mortise and at least two slots. In addition to (i) the contoured surface that forms part of the body when the block is fastened to the body, the block also has (ii) a lower side, (iii) a top platform that has a recess, a first hole, a second hole, and at least two alignment holes, where the first hole extends from the top platform through the lower side and aligns with a third hole in the back plate of the body, and the first hole is accessible from outside the instrument and is configured to receive a first fastener, the second hole extends from the top platform through the contoured surface and is accessible from outside the instrument and is configured to receive a second fastener, and in the at least two alignment holes, when the linear dovetail neck joint is fully assembled, one alignment hole aligns with and corresponds to each of the at least two slots in the bottom surface of the neck; and (iv) a back surface that has a window, an aperture, and an access port, where the aperture is configured to receive the intonation set screw, and the access port aligns with the channel in the top surface of the neck and is configured to receive the truss rod.

[0028] Provide at least two alignment pins. When the linear dovetail neck joint is fully assembled, one alignment pin is partially inserted into each of the at least two alignment holes in the top platform of the block and into the aligned and corresponding one of the at least two slots in the bottom surface of the neck. The alignment pins align the neck with the block and prevent side–to–side movement of the neck.

[0029] In addition to the main components of the neck and the block, the linear dovetail neck joint also includes some separable components. Among these separable components are a shim sleeve, one or more shims, a dovetail key, a spring cage, and a dovetail slider. Each of these components is summarized with reference to how it interacts with the neck, the block, and other separable components.

[0030] The shim sleeve is configured to be inserted into the window formed in the back surface of the block. The shim sleeve has a front face, a bottom with upright ribs to ensure correct orientation, and side walls, each side wall having a corresponding slot.

[0031] At least one substantially flat gasket is configured to be inserted into a gasket sleeve and engage the gasket sleeve in a conforming friction fit. The gasket has a top portion, a bottom, and side walls, wherein when the linear dovetail neck joint is fully assembled, the height of the top portion defines the distance by which the linear dovetail neck joint separates the neck from the body when the bottom surface of the neck rests on the top portion of the gasket. The bottom has a track configured to receive ribs of the gasket sleeve, and each of the side walls has a respective flexible and spring-like latch. Each latch includes a first protrusion configured to snap-engage in a respective slot in the side wall of the gasket sleeve when the gasket is fully located within the gasket sleeve. When the gasket is fully located within the gasket sleeve, a second protrusion extends a short distance beyond the front of the gasket sleeve and projects into a neck recess.

[0032] The dovetail key has a top, a bottom, and a central longitudinal axis, wherein a first opening and a second opening are each aligned along the axis and extend through the dovetail key from the top to the bottom. The first opening is aligned with a first hole in the block and is configured to receive a first fastener, and the second opening is aligned with a second hole in the block and is configured to receive a second fastener. Rotation of the first fastener and the second fastener in the corresponding first and second openings causes the fasteners to pull the dovetail key downward toward the top platform of the block and attach the dovetail key to the block.

[0033] The spring cage has a base with a top planar surface. The base is configured to fit snugly within a recess in the top platform of the block. The spring cage also has a plurality of springs that extend upwardly from the planar surface of the base and exert an upward force on the bottom of the dovetail key to hold the dovetail key in place against the downward pull of the fasteners. This upward force also aids in releasing the neck joint when needed.

[0034] Finally, the dovetail slider is configured to fit snugly within the mortise in the neck and reinforce the mortise in the neck. The dovetail slider engages the dovetail key when the neck is attached to the block, and the dovetail slider facilitates movement between the neck and the block. It also prevents deformation of either surface through appropriate hardness or tempering of the material.

[0035] It should be understood that the foregoing summary and the following detailed description are both exemplary but not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not drawn to scale. Instead, for clarity, the dimensions of the various features are arbitrarily enlarged or reduced. The drawings include the following figures:

[0037] Figure 1is a schematic perspective view of a conventional guitar;

[0038] Figure 2 is Figure 1 a schematic side view of the guitar shown;

[0039] Figure 3 is a bottom perspective view of the guitar neck, highlighting the neck components that form part of a linear dovetail neck joint;

[0040] Figure 4a is a rear perspective view of the guitar body, highlighting the body components that form part of a linear dovetail neck joint;

[0041] Figure 4b is a front perspective view of the body shown in Figure 4a;

[0042] Figure 5 depicts a guitar in which the neck and body are connected via a linear dovetail neck joint, highlighting the positions of the first and second holes;

[0043] Figure 6 is a front perspective view of an exemplary embodiment of a spacer sleeve that forms part of a linear dovetail neck joint;

[0044] Figure 7 is a front perspective view of an exemplary embodiment of a spacer that forms part of a linear dovetail neck joint;

[0045] Figure 8 is a perspective view of a linear dovetail neck joint in which the spacer is fully seated within the spacer sleeve;

[0046] Figure 9 is a front perspective view of an exemplary embodiment of a dovetail key that forms part of a linear dovetail neck joint;

[0047] Figure 10 depicts a dovetail key attached to the body;

[0048] Figure 11 is a front perspective view of an exemplary embodiment of a spring cage that forms part of a linear dovetail neck joint;

[0049] Figure 12 shows the spring cage seated within a recess in the top platform of the body;

[0050] Figure 13 is a front perspective view of an exemplary embodiment of a dovetail slider that forms part of a linear dovetail neck joint; and

[0051] Figure 14 depicts the spacer sleeve, spacer, dovetail key, spring cage, and dovetail slider of a linear dovetail neck joint that are already in place. Specific Embodiments

[0052] An improved system is provided for attaching the neck of a musical instrument to the instrument body such that the position of the neck relative to the body can be easily, quickly, accurately and repeatedly adjusted in both linear and angular directions. The system also allows the user to quickly adjust the linear distance between the nut and the bridge without changing the angle of the neck relative to the body. Thus, the user can quickly and efficiently change the string height of a guitar and adjust the intonation or scale length of the guitar.

[0053] A stringed instrument according to the present invention may include a guitar, such as an acoustic guitar, a solid body electric guitar, and an acoustic-electric guitar, but may also include other stringed instruments, such as a banjo, a mandolin, a violin, a xylophone, and / or other similar instruments. Although the principles of the present disclosure are described in connection with a guitar, it should be understood that the disclosed principles also apply to other stringed instruments having an instrument body and an elongated neck along which strings are stretched.

[0054] Reference is now made to the accompanying drawings, in which like reference numerals represent like elements in the various figures making up the drawings. Turning first to Figure 1 and Figure 2 , a brief description of various components of a stringed instrument according to the prior art and the present invention will now be discussed. As shown in these figures, a guitar 1 has a guitar body 2 connected to a neck 4 in a conventional manner. The body 2 includes a front plate 18a having a circular sound hole 28, a rear plate 18b facing the front plate 18a, and side plates 18c combined with the edges of the front plate 18a and the rear plate 18b in a spaced-apart manner. Sound resonance is generated in the internal space formed by the front plate 18a, the rear plate 18b, and the side plates 18c. In addition, an aperture is formed on one side of the body 2 into which the neck 4 is inserted.

[0055] The neck 4 takes the form of a beam 3 having a considerable thickness, with a top surface 5a and a bottom surface 5b. The neck 4 typically includes wood or some other similar or conventional material that is suitable for withstanding continuous string tension without warping or twisting. The neck 4 has an integral headstock 6 that holds a plurality of individual tuning pegs 8 (usually six or possibly twelve tuning pegs), each tuning peg in turn holding the free end of a desired string 10 in a conventional manner. The strings 10 are tightened with a considerable tension (e.g., about 30 pounds of tension per string) and extend from a first fixed point or fixed axis 12 to a second fixed axis 20, where the first fixed point or fixed axis 12 is formed by the nut 14 supported by a bridge 16 permanently attached to the front plate 18a of the guitar body 2, and the second fixed axis 20 is formed by a nut 22 permanently attached to the top surface 5a of the neck 4 and located near the headstock 6. In addition, a truss rod (not shown) is installed inside the beam 3 of the neck 4 to prevent the neck 4 from bending or twisting due to the tension of the guitar strings 10.

[0056] The fretboard (also known as the fingerboard 24 on stringed fret instruments) is an important part of most stringed fret instruments. The fingerboard 24 is a thin and long strip of hard material, usually a reinforced polymer or wood, such as rosewood or ebony, which mates with the top surface 5a of the neck 4 and is formed on the top surface 5a of the neck 4, thus being located between the remainder of the neck 4 and the strings 10 and separating the remainder of the neck 4 from the strings 10. The material for making the fingerboard 24 should be strong, durable and stable enough to support and hold the metal frets 9, which are installed at regular intervals on the top of the fingerboard 24 and can withstand the playing wear over many years of use. The strings 10 extend on the fingerboard 24 between the nut 22 and the bridge 16. For a conventional guitar 1, the heel 26 is integrally formed with the remainder of the neck 2 and extends from the bottom surface 5b of the neck 4.

[0057] When using the guitar 1, the musician moves his or her fingers up and down the neck 4, pressing on the strings 10 to shorten them and producing various pitches as the strings 10 are plucked, strummed or otherwise excited. Typically, the frets 9 on the fingerboard 24 extend across the width of the neck 4 in order to provide a location to anchor the ends of the shortened strings 10 at a definite or desired position.

[0058] In the case of an acoustic instrument such as the acoustic guitar 1, the body 2 encloses a resonant sound chamber. Plucking, strumming or otherwise exciting the strings 10 causes the strings 10 to vibrate. This vibration in turn causes the bridge 16 on which the strings 10 extend to also vibrate. In fact, for each note played, the bridge 16 forms the vibrating end point of the strings 10. The vibration of the bridge 16 in turn causes the front plate 18a (known as the soundboard) of the acoustic instrument to also vibrate, which in turn causes the air trapped in the sound chamber to move, thus producing the sound heard through the sound hole 28 when playing the instrument.

[0059] Typically, the strings 10 are tuned in pitch at the top of the neck 4 or the headstock 6, where the tuning machines 8 increase or decrease the tension on each string 10. Then, the user plays the desired note by plucking the string 10 near the middle of the guitar body 2 while pressing the string 10 extending on the neck 4 onto the fingerboard 24 attached to the top surface 5a of the neck 4. The timbre of the produced note depends on the tension of the string 10 and the distance between the fret 9 on the neck 4 where the string 10 is pressed and the lower anchor point. The smaller the distance between the pressed string 10 and the bridge 16, the higher the pitch of the produced timbre. Increasing the tension of the string 10 will also produce a note with a higher pitch.

[0060] Figure 3is a bottom perspective view of the neck 4, highlighting the components of the neck 4 that form part of the linear dovetail neck joint. The bottom surface 5b of the neck 4 has a mortise 30, preferably, but not necessarily, cut into the bottom surface 5b with a trapezoidal cross-section and a rectangular shape. The sides of the trapezoidal cross-section of the mortise 30 may be cut at an angle of approximately 28 degrees relative to the vertical direction. The width, length, and height of the mortise 30 may be approximately 1 inch (2.5 cm), 3.35 inches (8.5 cm), and 0.55 inches (1.4 cm). Of course, these dimensions are just examples. One of a pair of slots 32 is located on either side of the mortise 30, and the dimensions and shape of the slots 32 are designed to receive alignment pins 34 (see Figure 14 ). On the top surface 5a of the neck 4, a channel 36 (usually cut into the top surface 5a) is provided.

[0061] Figures 4a and 4b show the block 40, highlighting the components of the block 40 that form part of the linear dovetail neck joint. Figure 4a is a rear perspective view of the block 40, and Figure 4b is a front perspective view. The block 40 has a top platform 42 defined by an entire sidewall 44a, a rear wall 44c, and a partial sidewall 44b. The entire sidewall 44a extends along the entire length of the top platform 42; the partial sidewall 44b extends only along approximately one-third of the length of the top platform 42. The rear wall 44c connects the entire sidewall 44a and the partial sidewall 44b. The front of the block 40 is defined by a contoured surface 46 that forms part of the guitar body 2 when the block 40 is fastened (usually glued) to the guitar body 2. When the block 40 is fastened to the guitar body 2, the rear of the block 40 is defined by a flat surface 48 located inside the guitar body 2. The block 40 may be formed as a one-piece part. "One-piece" means a single part or a single integral portion that is complete in itself and has no additional parts, i.e., the part is formed as a single piece unit. Alternatively, the block 40 may be formed by fastening sections (usually using glue) together.

[0062] Although the block 40 can be made of plastic, the block 40 is preferably made of wood. Tests were conducted comparing the performance of the guitar 1 with the wooden block 40 and the plastic block 40. The results of these tests were that the guitar 1 with the wooden block 40 had a slightly higher amplitude in the fundamental frequency, a slightly higher amplitude in the mid-frequency range, a slightly lower amplitude in the high mid-frequency range, and again a higher amplitude in the high-frequency range. All results were approximately 6 dB or less. The wooden block 40 had better balance, clarity, and harmonic content compared to the plastic block 40. The guitar 1 with the plastic block 40 produced a flatter, dimensionless tone quality, producing fewer harmonics, sound depth, and overtones. The guitar 1 with the plastic block 40 suffered from harsh high notes. The sustain of the plastic block 40 was slightly longer, but this may be attributed to natural variations in construction and setup.

[0063] The top platform 42 of the block 40 has a recess 50 (usually cut therein). Not necessarily, but the recess 50 is preferably rectangular, approximately 1.44 inches (3.65 cm) by 0.875 inches (2.22 cm) in size, and approximately 0.930 inches (2.36 cm) deep. A pair of holes, namely a first hole 52a and a second hole 52b, are located near the short sides of the recess 50 in the top platform 42. Each of the first hole 52a and the second hole 52b is preferably (but not necessarily) circular and has a diameter of approximately 0.32 inches (0.80 cm). The first hole 52a extends from the top platform 42 to and through the lower side of the block 40 and can be accessed from the outside of the guitar 1 through a corresponding third hole 52c in the rear plate 18b of the body 2 of the guitar 1; the second hole 52b extends from the top platform 42 to and through the contoured surface 46 of the block 4 and can be accessed directly from the outside of the guitar 1.

[0064] Figure 5Depicts a guitar 1, where the neck 4 and the body 2 are connected via a linear dovetail neck joint, highlighting the positions of a first hole 52a and a second hole 52b in a block 40. The second hole 52b is closer to the neck-to-body joint than the first hole 52a, and the second hole 52b is recessed into an exposed portion of the block 40 (specifically, recessed into a contoured surface 46), and is visible and accessible from the outside. In contrast, when the stringed instrument is fully assembled, the first hole 52a is hidden from view. The first hole 52a can be accessed through a corresponding third hole 52c accurately aligned in a rear panel 18b of the body 2 of the guitar 1, which allows a user to access the first hole 52a (through the third hole 52c) without having to reach a hand into the sound hole 28 of the guitar 1. As is known to those skilled in the art, the third hole 52c can be reinforced with a protective or decorative grommet (not shown). The first hole 52a and the second hole 52b are configured to receive fasteners, such as bolts 54a and 54b, each fastener having a head with a slot. Conventional tools (such as an Allen wrench) can be used to engage the slot and rotate the fastener. Figure 5 Shows the block 40 attached to the body 2 of the guitar 1 at approximately the center of the body 2.

[0065] Returning to FIGS. 4a and 4b, the top platform 42 of the block 40 also has a first alignment hole 56a and a second alignment hole 56b (generally cut therein). Each of the first alignment hole 56a and the second alignment hole 56b is preferably (but not necessarily) circular and has a diameter of approximately 0.12 inches (0.30 cm). The first alignment hole 56a and the second alignment hole 56b form blind holes in the body of the block 40 into which alignment pins 34 can be partially inserted. When the alignment pins 34 are fully inserted into the alignment holes 56a and 56b, a portion of each alignment pin 34 protrudes outward from the alignment holes 56a and 56b (and above the top platform 42).

[0066] When inserted into the first alignment hole 56a and the second alignment hole 56b of the block 40, the alignment pins 34 assist the user in aligning the neck 4 with the block 40 when the neck 4 is engaged with the block 40. Specifically, the user aligns a pair of slots 32 in the neck 4 with portions of the alignment pins 34 that extend outside the alignment holes 56a and 56b, and inserts these portions into the slots 32 by pushing the neck 4 toward the block 40. When the linear dovetail neck joint is fully assembled, the alignment pins 34 prevent unwanted lateral movement between the neck 4 and the block 40.

[0067] The shelf 58 is formed in the block 40 and extends from the top platform 42 to the flat surface 48, below the rear wall 44c, and partially into each of the entire side wall 44a and the partial side wall 44b. The shelf 58 terminates at the flat surface 48 at a window 60 formed in the flat surface 48. The window 60 is surrounded by a notch 62. The window 60 has, for example, a substantially rectangular or oval shape, defining a width of approximately 2.33 inches (5.92 cm) and a height of approximately 0.375 inches (0.95 cm).

[0068] The flat surface 48 also has an aperture 64 that is configured to receive the intonation setting screw 68 (see Figure 14 ). As Figure 14 shown, the intonation setting screw 68 may have a head, or it may be headless. The aperture 64 is preferably (but not necessarily) circular and has a diameter of approximately 0.275 inches (0.70 cm). The aperture 64 extends completely through the rear wall 44c from the flat surface 48 to the open area ("neck cavity") defined by the entire side wall 44a, the rear wall 44c, the partial side wall 44b, the shelf 58, and the top platform 42. The user can access the intonation setting screw 68 through the sound hole 28.

[0069] The process of setting intonation involves adjusting the length of the string 10 by moving the neck 4 forward or backward. To shorten the overall scale length and compensate for flat intonation, the user typically loosens the intonation setting screw 68 with the help of a small screwdriver. To lengthen the overall scale length and compensate for sharp intonation, the user tightens the intonation setting screw 68. The intonation setting screw 68 moves the neck 4 relative to the block 40 (and thus relative to the body 2), adjusting the distance between the lower nut 14 and the upper nut 22, and thus adjusting the intonation of the guitar 1. In this way, the user can use the intonation setting screw 68 of the linear dovetail neck joint to fine-tune the intonation and the overall scale length, i.e., the vibrating length of the strings 10 of the guitar 1. The neck 4 is prevented from tilting towards the bass or treble side under string tension (i.e., preventing lateral movement of the neck 4) by the alignment pin 34, which allows adjustment along the (linear) intonation axis while maintaining a centered position relative to the bridge 16 of the guitar 1.

[0070] The flat surface 48 also has an access port 66. The access port 66 is formed (and typically cut into) the top of the rear wall 44c and, like the aperture 64, extends completely through the rear wall 44c from the flat surface 48 to the neck cavity. When the components are joined by the linear dovetail neck joint, the access port 66 of the block 40 is shaped to align with and engage the channel 36 in the neck 4. Typically, the access port 66 is U-shaped, with legs separated by a distance of approximately 0.385 inches (1 cm) and having a radius of curvature of approximately 0.192 inches (0.5 cm). When the guitar 1 is fully assembled, the access port 66 and the channel 36 combine to receive a conventional truss rod 86 (see Figure 14 ). The truss rod 86 is typically made of steel or titanium and has a diameter of approximately 0.16 inches (4 mm).

[0071] Although Figure 4A the aperture 64 is shown to the left of the access port 66, and Figure 4B the aperture 64 is shown to the right of the access port 66, the aperture 64 can be placed on the opposite side of the access port 66. In this alternative embodiment, the aperture 64 will be shown on the right side of the access port 66 in Figure 4A and on the left side of the access port 66 in Figure 4B . This alternative embodiment can accommodate left-handed and right-handed musicians, respectively.

[0072] Notably, the neck 4 of the linear dovetail neck joint does not have a conventional heel (similar to the heel 26 shown in Figure 2 ) and the block 40 of the linear dovetail neck joint has a contoured surface 46. The absence of a heel and the presence of the contoured surface 46 combine to allow the user better access to the upper frets 9 of the guitar 1 than a conventional acoustic instrument. The advantage is that extremely high fret accessibility is achieved in the upper register of the fretboard 24, even on an instrument with a conventional acoustic guitar depth (3+ inches or 7.6+ cm).

[0073] In addition to the main components of the neck 4 and the block 40, the linear dovetail neck joint includes a number of separable components. Among these separable components are a spacer sleeve 70, one or more shims 90, a dovetail key 110, a spring cage 130, and a dovetail slider 140. Each of the spacer sleeve 70, the one or more shims 90, the dovetail key 110, the spring cage 130, and the dovetail slider 140 is a separate, solid, one-piece component. Each of these components is highlighted below with reference to how they interact with the neck 4, the block 40, and the other separable components.

[0074] The spacer sleeve 70 is configured to be inserted into a window 60 formed in the flat surface 48 of the block 40. In fact, as best shown in Figure 6 ​Figure 6 A front perspective view of an exemplary embodiment of a gasket sleeve 70 that is part of a linear dovetail neck joint. The front face 72 of the gasket sleeve 70 is formed by a flange 74 located in a notch 62 of the window 60 such that when the gasket sleeve 70 is fully inserted into the window 60, the front face 72 of the gasket sleeve 70 is substantially flush with the flat surface 48 of the block 40. Thus, like the window 60, the front face 72 of the gasket sleeve 70 has a generally rectangular or oval shape with dimensions similar to, for example, those of the window 60. Although the gasket sleeve 70 may be inserted into the window 70 via a friction fit such that the gasket sleeve 70 may be removed from and replaced in the window 70, the gasket sleeve 70 is more typically attached (e.g., glued) to a position inside the window 70.

[0075] The gasket sleeve 70 has a top 76, a bottom 78, and a pair of side walls 80a and 80b. The top 76 defines a flat surface that extends only partially along the side walls 80a and 80b from the front face 72. In contrast, the bottom 78 defines a flat surface that extends completely along the side walls 80a and 80b from the front face 72. The bottom 78 has an upright rib 84 formed at the center of the bottom 78. Although the rib 84 may extend the entire length of the bottom 78, as Figure 6 shown, the rib 84 extends only along the bottom 78 to a position that terminates below the top 76 and at the top 76. Each of the side walls 80a and 80b has a corresponding slot 82a and 82b that are located near the junction between the side walls 80a and 80b and the flange 74 and a short distance behind the flange 74.

[0076] When the gasket sleeve 70 is fully inserted into the window 60 of the block 40, the top 76 contacts the underside of the rear wall 44c, the bottom 78 contacts the shelf 58, and the side walls 80a and 80b contact the entire side wall 44a and a portion of the side wall 44b of the block 40, respectively. These different points of contact provide suitable locations to glue the gasket sleeve 70 to its fully inserted position. In this position, the bottom 78 of the gasket sleeve 70 is below the top platform 42 of the block 40 (i.e., recessed into the shelf 58 and not flush with the top platform 42) to accommodate the height of the gasket 90.

[0077] The spacer sleeve 70 can be made of plastic and can be injection molded or additively manufactured using 3D printing (the term "additive manufacturing" can be used synonymously with 3D printing). The term "3D printing" encompasses a variety of processes in which materials are joined or solidified under computer control to create three-dimensional ("3D") objects, where the materials are added together (e.g., liquid molecules or powder particles are fused together), typically layer by layer. In 3D printing, the three-dimensional object is constructed from a computer-aided design (CAD) model. One of the key advantages of 3D printing is the ability to produce complex shapes or geometries. In an alternative embodiment, the spacer sleeve 70 can be made of a suitable metal such as stainless steel.

[0078] Figure 7 is a front perspective view of an exemplary embodiment of a spacer 90 that forms part of a linear dovetail neck joint. The spacer 90 is configured to be inserted into the spacer sleeve 70. The spacer 90 can be releasably inserted into and removed from the spacer sleeve 70. The geometry of the spacer 90 is sufficiently similar to the geometry of the spacer sleeve 70 such that the spacer 90 engages the spacer sleeve 70 in a snug, friction fit manner. The spacer 90 has a front face 92 on which a marking 91 can be depicted. The marking 91 can provide the user with various information, including in particular the dimensions of the spacer 90. Like the spacer sleeve 70, the spacer 90 can be made of plastic and can be injection molded or additively manufactured using 3D printing.

[0079] In an alternative embodiment, the spacer 90 can be made using liquid metal technology. Liquid metal is a member of a series or class of amorphous (non-crystalline) metal alloys, sometimes referred to as bulk metallic glasses because this material has some properties most closely associated with glass. Liquid metal combines many desirable material characteristics, including high tensile strength, excellent corrosion resistance, a very high coefficient of restitution, and excellent anti-wear characteristics, while also being able to be thermoformed in a process similar to thermoplastics. The atomic structure of amorphous metals results in a low shrinkage rate (0.4%) during molding and allows for the production of complex parts with high precision (±0.0008 inches or 0.02 mm). Liquid metal is a potential alternative to plastics in many applications where plastics are currently used. Plastics are flexible but not strong, while metals, although stronger than plastics, are not as flexible as plastics. Liquid metal offers a favorable compromise: batches of amorphous steel have been produced that are three times as strong as conventional steel alloys.

[0080] The spacer 90 also has a stepped top with a higher top portion 96a and a lower top portion 96b, a bottom 98, and a pair of side walls 100a and 100b. The higher top portion 96a of the spacer 90 defines a flat surface that extends only partially along the side walls 100a and 100b from the front 92, and is sized and shaped to engage the underside of the top 76 of the spacer sleeve 70 when the spacer 90 is fully inserted into the spacer sleeve 70. The lower top portion 96b of the spacer 90 defines a flat surface that extends from the end of the higher top portion 96a to the remaining length of the side walls 100a and 100b. The height of the lower top portion 96b defines the size of the spacer 90, as reflected by the marking 91, and the distance by which the linear dovetail neck joint separates the neck 4 from the block 40 and thus the body 2 of the guitar 1 (discussed below).

[0081] The bottom 98 defines a flat surface that extends completely along the side walls 100a and 100b from the front 92. The bottom 98 has a track 104 formed (e.g., cut) in its center. As Figure 7 depicted by the dashed line in, the track 104 extends completely along the side walls 100a and 100b from near the front 92. Typically, the track 104 starts a short distance (e.g., about 0. or 1.65 mm) behind the front 92. The track 104 is sized and shaped (having a width of, for example, about 0.1 inches or 2.5 mm) to receive the rib 84 of the spacer sleeve 70 via a sliding, friction fit. Thus, when the user desires to insert the spacer 90 into the spacer sleeve 70, the user aligns the track 104 with the rib 84 and pushes the spacer 90 forward into the spacer sleeve 70. As the user continues to insert the spacer 90, the rib 84 slides along the track 104. The engagement between the rib 84 of the spacer sleeve 70 and the track 104 of the spacer 90 ensures proper alignment and orientation when the spacer 90 is inserted and prevents the user from inserting the spacer 90 into the spacer sleeve 70 in an incorrect orientation (i.e., the engagement makes the insertion substantially foolproof). Thus, the spacer 90 has a one-way compatibility with the spacer sleeve 70 to ensure that the spacer 90 is installed only in the correct orientation.

[0082] Each of the side walls 100a and 100b has corresponding latches 94a and 94b located near the junctions between the side walls 100a and 100b and the front face 92. Each latch has a first protrusion 93 located just behind the front face 92 and a second protrusion 95 located just in front of the front face 92. The first protrusion 93 and the second protrusion 95 each extend laterally beyond the corresponding side walls 100a, 100b of the gasket 90. When the gasket 90 is fully inserted into the gasket sleeve 70, the second protrusion 95 also extends beyond the front face 92 and can be grasped by the user. The second protrusion 95 has a plurality of ridges to assist the user in gripping. The latches 94a and 94b are flexible and form spring-like elements in the side walls 100a and 100b.

[0083] When the user aligns the track 104 of the gasket 90 with the rib 84 of the gasket sleeve 70 and pushes the gasket 90 forward into the gasket sleeve 70, the higher top portion 96a of the gasket 90 slidably engages the top 76 of the gasket sleeve 70, the bottom 98 of the gasket 90 slidably engages the bottom 78 of the gasket sleeve 70, the side wall 100a of the gasket 90 slidably engages the side wall 80a of the gasket sleeve 70, and the side wall 100b of the gasket 90 slidably engages the side wall 80b of the gasket sleeve 70. The user continues to push the gasket 90 forward into the gasket sleeve 70 against the frictional forces generated by these engagements until the first protrusion 93 contacts the front face 92 of the gasket sleeve 70 and is blocked by it.

[0084] At this time, the user presses the second protrusions 95 towards each other and towards the center of the gasket 90 in the direction of arrow 102 and against the spring forces of the latches 94a, 94b (the spring forces bias the latches 94a, 94b to positions parallel to the side walls 100a, 100b). This action allows the first protrusion 93 to slide past the front face 92 of the gasket sleeve 70 and slide a short distance along the side walls 80a, 80b of the gasket sleeve 70 until the first protrusion 93 reaches the corresponding slots 82a, 82b in the side walls 80a, 80b. Then, the first protrusion 93 snaps into engagement with the corresponding slots 82a, 82b in the side walls 80a, 80b in the direction opposite to arrow 102 under the drive of the spring force, causing the latches 94a, 94b to return to their positions parallel to the side walls 100a, 100b, and the first protrusion 93 extends through the slots 82a, 82b and "locks" onto the side walls 80a, 80b. This latching prevents the gasket 90 from being removed from the gasket sleeve 70 until and unless the user desires to remove the gasket 90.

[0085] The snap engagement produces an audible "click" and a tactile confirmation that can be perceived by the user, each informing the user that the gasket 90 is fully in place and secured within the gasket sleeve 70. In this position, as Figure 8 depicted, Figure 8is a perspective view of a linear dovetail neck joint, where the shim 90 is fully seated within the shim sleeve 70, the front face 92 of the shim 90 is substantially flush with the front face 72 of the shim sleeve 70, and the second protrusion 95 of the shim 90 extends a short distance beyond the front face 72 of the shim sleeve 70; this distance is sufficient to allow a user to access the second protrusion 95 when the user desires to remove the shim 90 from the shim sleeve 70. To effect removal, which may be desirable when the user wants to replace one shim 90 having a lower top portion 96b of a first height with another shim 90 having a lower top portion 96b of a different second height, the user again presses the second protrusions 95 towards each other and towards the center of the shim 90 in the direction of arrow 102 while pulling on the second protrusions 95. These combined actions release the first protrusions 93 from engagement in the respective slots 82a, 82b of the sidewalls 80a, 80b and slide the shim 90 out of the shim sleeve 70.

[0086] As mentioned above, the height of the lower top portion 96b of the shim 90 defines the distance by which the end of the neck 4 is separated from the bottom surface of the neck cavity contained within the block 40 by the linear dovetail neck joint and thus defines the angle between the neck 4 and the body 2 of the guitar 1. Specifically, when the linear dovetail neck joint is fully assembled, the leading edge of the bottom surface 5b of the neck 4 rests on the lower top portion 96b of the shim 90. The minimum height of the lower top portion 96b of the shim 90 may be identified as a "zero" height, and when the shim 90 is fully inserted into the shim sleeve 70 and abuts the top platform 42, the lower top portion 96b of the shim 90 is substantially flush with or aligned with the top platform 42 of the block 40. Thus, for a shim 90 of "zero" height, the bottom surface 5b of the neck 4 rests on the lower top portion 96b of the shim 90 and the top platform 42 of the block 40.

[0087] However, the lower top portion 96b of the shim 90 can have any desired height, and conceivably, the user will have (and may have already purchased a pack of shims 90) multiple shims 90 of different sizes, each shim having a lower top portion 96b of a different height. Thus, the lower top portion 96b of the shim 90 can have a height such that when the shim 90 is fully inserted into the shim sleeve 70 and abuts against the top platform 42, the lower top portion 96b extends 0, 0.025 inches (0.6 mm), 0.04 inches (1 mm), or any other suitable distance known to a person skilled in the art above the top platform 42 of the block 40. Of course, the markings 91 of these exemplary shims 90 can be "zero shim", "0.025-inch shim", and "0.040-inch shim", respectively. The markings 91 of these exemplary shims 90 can also be "zero", "0.025 inches", and "0.040 inches", respectively. For shims 90 of any height other than the "zero" height, the bottom surface 5b of the neck 4 only rests on the lower top portion 96b of the shim 90 and not on the top platform 42 of the block 40 (since it is above the top platform 42 of the block 40).

[0088] When using a shim 90 with a height greater than the "zero" shim, the string height is closer to the fret 9. As a result, the playability can be customized according to the user's preference. The interchangeable neck lift shims 90 allow for a range of neck height adjustments depending on the player's preference for string height (guitar string height). The neck lift shims 90 allow for adjustment according to preference because they will be manufactured in different heights according to optimized string instrument string height settings.

[0089] The shim 90 can be substantially flat or wedge-shaped to correspond to various neck angles. A linear dovetail neck joint can accept or accommodate multiple shim heights, such as three different shim heights, six different shim heights, or some other suitable number of shim heights. Although some conventional designs require two separate surfaces to be shimmed, only one surface utilizes the interchangeable shims 90 in a linear dovetail neck joint.

[0090] Figure 9 is a front perspective view of an exemplary embodiment of a dovetail key 110 that is part of a linear dovetail neck joint. Preferably, the dovetail key 110 is made of metal. The exemplary embodiment of the dovetail key 110 has a top 116, a bottom 118, and a side 120 between the top 116 and the bottom 118. The edges between the top 116 and the side 120 and between the bottom 118 and the side 120 can be beveled or not beveled. The dovetail key 110 can have any one of a variety of suitable shapes; for example, Figure 9The substantially rectangular or oval shape shown (where the sides 120 have four radii of curvature) works well. Suitable dimensions for the dovetail key 110 are a length of approximately 2.625 inches (6.67 cm), a width of approximately 0.95 inches (2.41 cm), and a height of approximately 0.350 inches (0.90 cm). Preferably, the cross-section of the dovetail key 110 is trapezoidal.

[0091] The dovetail key 110 has two threaded openings: a first opening 112a and a second opening 112b. The first opening 112a and the second opening 112b are aligned along the central longitudinal axis of the dovetail key 110 and are located at the center of the width of the dovetail key 110, and each opening extends completely through the height of the dovetail key 110 from the top 116 to the bottom 118. The first opening 112a is configured to align with a first hole 52a in the block 40 when the dovetail key 110 is attached to the block 40; the second opening 112b is configured to align with a second hole 52b in the block 40 when the dovetail key 110 is attached to the block 40. As Figure 10 、 Figure 12 and Figure 14 depicted, the dovetail key 110 is attached to the block 40 using bolts 54a and 54b.

[0092] More specifically, the bolt 54a is inserted through the first hole 52a in the block 40 until the bolt 54a extends upward a distance above the top platform 42 of the block 40. The bolt 54b is similarly inserted through the second hole 52b in the block 40 until the bolt 54b extends upward a distance above the top platform 42 of the block 40. The dovetail key 110 is then positioned above the top platform 42 such that the first opening 112a aligns with the first hole 52a and receives the bolt 54a, while the second opening 112b aligns with the second hole 52b and receives the bolt 54b. Rotation of the bolts 54a, 54b in the corresponding threaded first opening 112a and second opening 112b causes the bolts 54a, 54b to pull the dovetail key 110 downward toward the top platform 42 and attach the dovetail key 110 to the block 40. As mentioned above, the user can employ a conventional tool (such as an Allen wrench) to engage the slots in the heads of each of the bolts 54a, 54b and rotate the bolts 54a, 54b.

[0093] Figure 11is a front perspective view of an exemplary embodiment of a spring cage 130 that forms part of a linear dovetail neck joint. The exemplary embodiment of the spring cage 130 has a substantially rectangular base 132 that defines a top planar surface 134. A plurality of springs 136, each integral with the base 132, extend upwardly an equal amount above the planar surface 134 of the base 132. The spring cage 130 is sized and shaped (i.e., constructed to) fit snugly and frictionally engage within a recess 50 of a top platform 42 of a block 40. The spring cage 130 may (but is not necessarily) be attached (e.g., glued) to the block 40. Figure 12 Shows the position of the spring cage 130 within the recess 50 of the top platform 42 of the block 40.

[0094] The function of the springs 136 of the spring cage 130 is to push upwardly against the bottom 118 of the dovetail key 110 (i.e., provide lift for the dovetail key 110) when the dovetail key 110 is pulled downwardly toward the top platform 42 under the action of bolts 54a, 54b. This upward force also helps to release the neck joint when desired. The force of the springs 136 against the bottom 118 of the dovetail key 110 must be substantially equal and symmetrically distributed such that the force is balanced and distributed with respect to the dovetail key 110, and the springs 136 must provide sufficient upward resistance to overcome the downward pull of bolts 54a and 54b to hold the dovetail key 110 in place. A single spring 136 and two springs 136 are insufficient to meet these requirements. Instead, three springs 136 of the preferred embodiment of the spring cage 130 function well, with one of the three springs 136 facing a first longitudinal direction and the other two springs 136 facing opposite longitudinal directions. The spring cage 130 may be made of plastic and may be additively manufactured using 3D printing. In an alternative embodiment, the spring cage 130 may be made using liquid metal technology.

[0095] Figure 13is a front perspective view of an example embodiment of a dovetail slider 140 that forms part of a linear dovetail neck joint. An example embodiment of the dovetail slider 140 has a head 142 and two legs 144a and 144b. The size and shape of the dovetail slider 140 are designed (i.e., constructed to) fit snugly within the mortise 30 in the neck 4. Thus, like the mortise 30, the dovetail slider 140 is preferably (but not necessarily) trapezoidal in cross-section and rectangular in shape. The legs 144a and 144b of the dovetail slider 140 may be formed at an angle of approximately 28 degrees with respect to the vertical direction. The width, length, and height of the dovetail slider 140 are substantially the same as the corresponding dimensions of the mortise 30. The dovetail slider 140 may be held in the mortise 30 via a friction fit or may be attached (e.g., glued) in the mortise 30. One function of the dovetail slider 140 is to reinforce the mortise 30, thereby reducing the risk of cracks in the neck 4 that may be caused by the downward pressure of the dovetail key 110.

[0096] Another function of the dovetail slider 140 is to facilitate movement between the neck 4 and the block 40. More specifically, the dovetail slider 140 forms a guide within the mortise 30 of the neck 4. As Figure 14 shown, when the user attaches the neck 4 to the block 40, the dovetail key 110 engages (i.e., slides into) the dovetail slider 140. ( Figure 14 Also depicted are the shim sleeve 70, shim 90, and spring cage 130 of the linear dovetail neck joint in place.) The dovetail slider 140 minimizes the friction that might otherwise limit the sliding movement of the dovetail key 110 into the mortise 30. The dovetail slider 140 may be made of metal (which is preferred, especially if the dovetail key 110 is made of metal) or a plastic material such as polypropylene. However, the dovetail slider 140 is made of a different material than the dovetail key 110 (even if both are metal) to prevent galling between the two mating surfaces. The dovetail slider 140 may be lubricated to facilitate movement of the neck 4 within the block 40. However, for self-lubricating materials such as metal or polypropylene, providing the best surface for movement of the neck 4 relative to the block 40 does not require lubrication.

[0097] As the dovetail key 110 is inserted into the dovetail slider 140 (and thus into the mortise 30 of the neck 4), the user can tighten bolts 54a and 54b from the exterior of the guitar 1, thereby pulling the dovetail key 110 downward toward the block 40 against the upward force of the spring cage 130. This action simultaneously pulls the neck 4 downward into engagement with the block 40 and the body 2 of the guitar 1. The user continues to tighten bolts 54a and 54b until the neck 4 is firmly and securely pulled into position within the block 40. As tightening occurs, the neck 4 rotates incrementally on the alignment pins 34. The reverse action (i.e., loosening bolts 54a and 54b) disengages the neck 4 from the body 2 and ultimately permits the neck 4 to be removed from the body 2. The upward force of the spring cage 130 facilitates this disengagement and removal.

[0098] The linear dovetail neck joint permits the user to vary the height between the neck 4 and the body 2, the angle between these instrument components, or both the height and angle. The two bolts 54a and 54b that engage the dovetail key 110 might suggest that adjusting one bolt (e.g., bolt 54a) a different amount than the other bolt (e.g., bolt 54b) could affect the angle. However, the user must tighten bolts 54a and 54b with the same torque setting to properly couple the neck 4 and the body 2.

[0099] Accordingly, the function of the linear dovetail neck joint is to fasten the neck 4 to the body 2 of the guitar 1 using an internal dovetail with screw-adjustable tension. There are no bolts or permanent adhesives directly bonding the neck 4 to the body 2. In fact, no fasteners or threaded inserts directly enter or are screwed into the neck 4. The neck 4 is fastened to the body 2 by indirect coupling while the linear dovetail neck joint applies a uniform, adjustable downward tension on the neck 4. The linear dovetail neck joint does not require removal of the neck 4 from the block 40 to adjust the position of the neck 4 relative to the body 2 of the guitar 1. However, the neck 4 can be removed from the body 2 using the linear dovetail neck joint, thereby permitting the user to adjust or replace the neck 4. The linear dovetail neck joint allows the user to easily interchange the necks 4 of the guitar 1.

[0100] In addition, conventional designs require complete removal of the neck 4 from the body 2 to access shims for neck adjustment. With the linear dovetail neck joint, shims 90 can simply be interchanged by loosening the linear dovetail neck joint and snapping the replacement shim 90 into place as needed. This feature is more convenient for both manufacturing and the end consumer. In production, this feature permits the bridge 16 and the nut 14 of the stringed instrument to have a uniform size compared to conventional combinations of several (e.g., three) different bridges and many (e.g., five) different nut heights to obtain the correct geometry. The correct geometry can now be reliably established at the neck joint by using shims 90 without repeated disassembly.

[0101] The linear dovetail neck joint allows for excellent fret access in the upper register of the fretboard 24, easier neck adjustment, intonation correction, and a unique front block construction with hand relief, all without the need for adhesives. It allows for a practical and aesthetically pleasing neck-to-body joint without the need for a heel 26 on the neck 4. The result is a neck-to-body joint that is easy to play, easy to adjust, and easy to repair.

[0102] Although the invention has been illustrated and described above with reference to specific embodiments and examples, the invention is not limited to the details shown. Instead, various modifications may be made to the details within the scope of the equivalents of the claims without departing from the spirit of the invention. For example, all ranges widely recited in this document are included within their scope, and all narrower ranges fall within the broader ranges.

Claims

1. A linear dovetail neck joint for a musical instrument, the musical instrument having a body, the linear dovetail neck joint comprising: a neck having a bottom surface with a mortise; a block having a contoured surface, a top platform, and a rear surface, wherein the contoured surface forms part of the body when the block is fastened to the body, the top platform having a hole accessible from the exterior of the musical instrument, the hole being configured to receive a fastener, and the rear surface having a window; a shim sleeve configured to be inserted into the window in the block; at least one substantially flat or angled shim configured to be inserted into the shim sleeve, the shim having a top portion, the height of the top portion defining the distance by which the linear dovetail neck joint separates the neck from the block when the bottom surface of the neck rests on the top portion when the linear dovetail neck joint is fully assembled; and a dovetail key that at least indirectly engages the mortise of the neck, and the dovetail key having a top, a bottom, and an opening extending from the top through the dovetail key to the bottom, wherein the opening is aligned with the hole of the block and is configured to receive the fastener, and wherein rotation of the fastener in the opening causes the fastener to pull the dovetail key, together with the neck, downwardly toward the top platform of the block and attach the dovetail key and the neck to the block.

2. The linear dovetail neck joint according to claim 1, wherein, The linear dovetail neck joint has no screws directly entering the neck or roots on the neck.

3. The linear dovetail neck joint according to claim 1, wherein, The top platform of the block has a recess, and the linear dovetail neck joint further includes a spring cage having: a base, wherein the base has a top planar surface, the base being configured to fit snugly in the recess of the top platform of the block; and a plurality of springs extending upwardly in the direction of the planar surface of the base and applying an upward force to the bottom of the dovetail key to hold the dovetail key in place against the downward pull of the fastener.

4. The linear dovetail neck joint according to claim 1, further comprising a dovetail slider configured to fit snugly within the mortise in the neck and reinforce the mortise in the neck, the dovetail slider engaging the dovetail key when the neck is attached to the block, and the dovetail slider facilitating movement between the neck and the block.

5. The linear dovetail neck joint according to claim 1, wherein, The rear surface of the block has an aperture, and the linear dovetail neck joint further includes a tuning screw received in the aperture for moving the neck relative to the body and adjusting the tuning of the musical instrument.

6. The linear dovetail neck joint according to claim 1, wherein, The bottom surface of the neck has at least two slots, and the top platform of the block has at least two alignment holes, wherein when the linear dovetail neck joint is fully assembled, one alignment hole aligns with and corresponds to each of the at least two slots in the bottom surface of the neck, and the linear dovetail neck joint further includes at least two alignment pins, when the linear dovetail neck joint is fully assembled, one alignment pin is partially inserted into each of the at least two alignment holes in the top platform of the block, and inserted into the aligned and corresponding one of the at least two slots in the bottom surface of the neck, the alignment pins align the neck with the block and prevent lateral movement of the neck.

7. The linear dovetail neck joint according to claim 1, wherein, The neck has a top surface, the top surface has a channel configured to receive a truss rod, and the block has an access port aligned with the channel in the top surface of the neck, the access port being configured to receive the truss rod.

8. The linear dovetail neck joint according to claim 1, wherein, The body has a third hole, the block has a lower side, and the top platform of the block has a second hole extending through the lower side from the top platform, the second hole being aligned with the third hole in the body, the second hole being accessible from the outside of the instrument and configured to receive a second fastener.

9. The linear dovetail neck joint according to claim 8, wherein, The dovetail key has a second opening and a central longitudinal axis, wherein the second opening extends from the top through the dovetail key to the bottom, the opening and the second opening are each aligned along the central longitudinal axis, wherein the second opening is aligned with the second hole of the block and configured to receive the second fastener, and wherein rotation of the second fastener in the corresponding second opening causes the second fastener to pull the dovetail key downward toward the top platform of the block and attach the dovetail key to the block.

10. The linear dovetail neck joint according to claim 1, wherein, The spacer sleeve has a front face, a bottom with upright ribs, and side walls, each of the side walls having a corresponding slot.

11. The linear dovetail neck joint according to claim 10, wherein, The at least one substantially flat or angled spacer is configured to engage the spacer sleeve in a snug friction fit, the spacer having a bottom and side walls, the bottom having tracks configured to receive the ribs of the spacer sleeve, and each side wall having a corresponding flexible and spring-like latch, the latch including a first protrusion and a second protrusion, the first protrusion being configured to snap-engage in the corresponding slot in the side wall of the spacer sleeve when the spacer is fully located in the spacer sleeve, and the second protrusion being configured to extend a short distance beyond the front face of the spacer sleeve when the spacer is fully located in the spacer sleeve.

12. The linear dovetail neck joint according to claim 1, wherein, The instrument has a nut, a saddle, and a linear distance between the nut and the saddle, and the linear dovetail neck joint is configured to adjust the linear distance between the nut and the saddle without any change in the angle of the neck relative to the body.

13. The linear dovetail neck joint according to claim 1, wherein, The block is made of wood.

14. The linear dovetail neck joint according to claim 1, further comprising a plurality of shims, each shim having a different size.

15. The linear dovetail neck joint according to claim 14, wherein, Each of the plurality of shims depicts a mark indicating the size of the shim.

16. An instrument, comprising the linear dovetail neck joint according to claim 1.

17. The musical instrument according to claim 16, wherein, The instrument is a guitar.

18. A linear dovetail neck joint for an instrument, the instrument having a body with a back plate including a third hole, the linear dovetail neck joint comprising: A neck having a top surface and a bottom surface, wherein the top surface has a channel configured to receive a truss rod, and the bottom surface has a mortise and at least two slots; A intonation setting screw for moving the neck relative to the body and adjusting the intonation of the instrument; A block having (i) a contoured surface that forms part of the body when the block is fastened to the body, (ii) a lower side, (iii) a top platform having a recess, a first hole, a second hole, and at least two alignment holes, wherein the first hole extends from the top platform through the lower side and aligns with the third hole in the back plate of the body, the first hole being accessible from the outside of the instrument and configured to receive a first fastener, the second hole extends from the top platform through the contoured surface, and the second hole is accessible from the outside of the instrument and configured to receive a second fastener, wherein, when the linear dovetail neck joint is fully assembled, one of the alignment holes aligns with and corresponds to each of the at least two slots in the bottom surface of the neck; and (iv) a rear surface having a window, an aperture, and an access port, wherein the aperture is configured to receive the intonation setting screw, and the access port aligns with the channel in the top surface of the neck and is configured to receive the truss rod; At least two alignment pins, when the linear dovetail neck joint is fully assembled, one alignment pin is partially inserted into each of the at least two alignment holes in the top platform of the block and into an aligned and corresponding one of the at least two slots in the bottom surface of the neck, the alignment pins aligning the neck with the block and preventing lateral movement of the neck; A shim sleeve configured to be inserted into the window in the block, the shim sleeve having a front face, a bottom with upright ribs, and side walls, each side wall having a corresponding slot; At least one substantially flat or angled spacer, the spacer being configured to be inserted into the spacer sleeve and to engage the spacer sleeve in a snug friction fit, the spacer having a top portion, a bottom, and sidewalls, wherein when the linear dovetail neck joint is fully assembled, the height of the top portion defines the distance by which the linear dovetail neck joint separates the neck from the body when the bottom surface of the neck rests on the top portion, the bottom having a track for receiving ribs of the spacer sleeve, and each sidewall having a respective flexible and spring-like latch, the latch including a first protrusion and a second protrusion, wherein the first protrusion is configured to snap-fit into a respective slot in the sidewall of the spacer sleeve when the spacer is fully within the spacer sleeve, and the second protrusion extends a short distance beyond the front of the spacer sleeve when the spacer is fully within the spacer sleeve; A dovetail key having a top, a bottom, and a central longitudinal axis, a first opening and a second opening both being aligned along the axis and extending from the top through the dovetail key to the bottom, wherein the first opening is aligned with the first hole of the block and is configured to receive the first fastener, and the second opening is aligned with the second hole of the block and is configured to receive the second fastener, and wherein rotation of the first fastener and the second fastener in the corresponding first and second openings causes the fasteners to pull the dovetail key downwardly towards the top platform of the block and to attach the dovetail key to the block; A spring cage having a base and a plurality of springs, the base having a top planar surface, the base being configured to fit snugly in the recess of the top platform of the block, the plurality of springs extending upwardly from the planar surface of the base and applying an upward force against the bottom of the dovetail key to hold the dovetail key in place against the downward pull of the fasteners; and A dovetail slider configured to fit snugly within the mortise in the neck and to reinforce the mortise in the neck, the dovetail slider engaging the dovetail key when the neck is attached to the block and facilitating movement between the neck and the block.

19. An instrument comprising the linear dovetail neck joint according to claim 18.

20. The musical instrument according to claim 19, wherein, The instrument is a guitar.

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