Offset golf shaft and coupling apparatus

Abstract

In a golf club, an apparatus which provides for a shaft to be adjustably secured to a head comprises a skewed axis shaft coupling and a shaft having an intermediate shaft section which joins a nominal shaft section to an offset shaft section such that they are offset one from the other. A shaft indexing mechanism provides for the nominal shaft section to have a plurality of indexed rotational positions in a socket of the skewed axis shaft coupling, thereby providing for the head to have, with respect to the offset shaft section, a plurality of possible sets of spatial and mass distribution properties. Furthermore, the skewed axis shaft coupling provides for the head to have, with respect to the nominal shaft section, a plurality of sets of angular properties.

Claims

1. A golf club comprising: a head; a shaft coupling; a shaft; and a fastening mechanism; wherein the head comprises a hosel with a hosel axis; wherein the shaft coupling comprises a socket with a socket axis; wherein the shaft comprises a nominal shaft section, an offset shaft section, and an intermediate shaft section which connects the offset shaft section to the nominal shaft section such that they are offset one from the other; wherein the offset shaft section comprises an upper offset shaft portion and a lower offset shaft portion, and the shaft comprises a first piece comprising the nominal shaft section, the intermediate shaft section, and the lower offset shaft portion, and the shaft comprises a second piece, joined to the first piece, comprising the upper offset shaft portion, wherein the fastening mechanism secures the nominal shaft section in the socket and it secures the shaft coupling in the hosel; wherein the shaft coupling further comprises a coupling component which, when the shaft coupling is secured in the socket, skews the socket axis with respect to the hosel axis; wherein the nominal shaft section embodies a shaft indexing structure, the socket embodies a socket indexing structure, and there are a plurality of rotational positions of the shaft indexing structure with respect to the socket indexing structure in which these indexing structures can engage to restrain rotation of the nominal shaft section with respect to the socket, thereby providing for a plurality of available sets of spatial and mass distribution properties of the head with respect to the offset shaft section; wherein the shaft coupling embodies a coupling indexing structure, the hosel embodies a hosel indexing structure, and there are a plurality of rotational positions of the coupling indexing structure with respect to the hosel indexing structure in which these indexing structures can engage to restrain rotation of the coupling component with respect to the hosel, thereby providing for a plurality of available sets of angular properties of the head with respect to the nominal shaft section; whereby, with the shaft indexing structure engaged with the socket indexing structure, the golf club has one of the available sets of spatial and mass distribution properties of the head with respect to the offset shaft section, and with the coupling indexing structure engaged with the hosel indexing structure, the golf club has one of the available sets of angular properties of the head with respect to the nominal shaft section.

2. The golf club of claim 1 wherein a bushing is affixed to the nominal shaft section, the fastener secures the bushing in the socket, and the bushing comprises a bushing indexing structure which operates as the shaft indexing structure.

3. The golf club of claim 2 wherein the fastening mechanism comprises a threaded fastener which passes through a hole in the hosel and engages a threaded hole in the bushing.

4. The golf club of claim 1 wherein the first piece is constructed using a metal and the second piece is constructed using a carbon fiber.

5. The golf club of claim 1 wherein the offset shaft section has an offset shaft axis about which it is substantially symmetric, the nominal shaft section has a nominal shaft axis about which it is substantially symmetric, and the nominal shaft axis, the offset shaft axis, and the hosel axis are substantially co-planar.

6. The golf club of claim 5 wherein the head has a face line which is also substantially co-planar.

7. The golf club of claim 1 wherein the shaft coupling is a skewed fitting shaft coupling.

8. The golf club of claim 1 wherein the shaft coupling is a skewed shim shaft coupling.

9. An assemblage used to provide any one of a plurality of golf club assemblies, the assemblage comprising: a head comprising a hosel with a hosel axis; and an offset shaft and coupling apparatus comprising a shaft, a shaft coupling, and a fastening mechanism; wherein the shaft coupling comprises a socket with a socket axis; wherein the shaft comprises a nominal shaft section, an offset shaft section, and an intermediate shaft section which connects the offset shaft section to the nominal shaft section such that the offset shaft section is offset from the nominal shaft section; wherein the fastening mechanism provides for the nominal shaft section to be secured in the socket and for the shaft coupling to be secured in the hosel; wherein the shaft coupling further comprises a coupling component which, when the shaft coupling is secured in the hosel, skews the socket axis with respect to the hosel axis; wherein the nominal shaft section embodies a shaft indexing structure and the socket embodies a socket indexing structure, and engagements of these indexing structures provide for the nominal shaft section to be, with respect to the socket, rotationally restrained in any of a plurality of indexed rotational positions; and wherein the shaft coupling embodies a coupling indexing structure and the hosel embodies a hosel indexing structure, and engagements of these indexing structures provide for the shaft coupling to be, with respect to the hosel, rotationally restrained in any of a plurality of indexed rotational positions; whereby the plurality of golf club assemblies have a plurality of sets of spatial and mass distribution properties of the head with respect to the offset shaft section and a plurality of sets of angular properties of the head with respect to the nominal shaft section.

10. A golf club comprising a head, a shaft, and a fastening mechanism: wherein the head includes a hosel which embodies a hosel indexing structure; wherein the shaft comprises a nominal shaft section, an offset shaft section, and an intermediate shaft section which joins the offset shaft section to the nominal shaft section such that they are offset one for the other; wherein, when the shaft is secured to the head by the fastening mechanism, the nominal shaft section, with respect to the offset shaft section, is proximal to the head; wherein the nominal shaft section embodies a shaft indexing structure; wherein a shaft coupling, comprising a fitting, a socket located in the fitting, a fitting indexing structure, and a socket indexing structure, is located between the nominal shaft section and the hosel, and the fitting indexing structure, cooperating with the hosel indexing structure, restrains rotation of the fitting in one of a plurality of rotational positions of the fitting with respect to the hosel, and the socket indexing structure, cooperating with the shaft indexing structure, restrains rotation of the nominal shaft section in one of a plurality of rotational positions of the nominal shaft section with respect to the socket, whereby the nominal shaft section is restrained from rotation in one of a plurality of rotational positions with respect to the hosel and the golf club has one of a plurality of sets of spatial and mass distribution properties of the head with respect to the offset shaft section.

11. The golf club of claim 3 wherein the fitting is a skewed axis fitting, whereby the golf club has one of a plurality of sets of angular properties of the head with respect to the nominal shaft section.

12. The golf club of claim 3 wherein a skewed shim is located between the hosel and the fitting, whereby the golf club has one of a plurality of sets of angular properties of the head with respect to the nominal shaft section.

Description

DRAWINGSFIGURES

(1) Drawings of the present invention are as follows:

(2) FIG. 1 is an exploded view of a first assemblage comprising a first embodiment of an apparatus of this invention, and

(3) FIGS. 2, 3, 4, and 5 are views of the first assemblage assembled in four different positions.

(4) FIG. 6 shows an exploded view of a second assemblage comprising a second embodiment of the apparatus, and

(5) FIG. 7 is an assembled view of the second assemblage.

DRAWINGSREFERENCE NUMERALS

(6) 5 offset shaft and coupling apparatus, first embodiment 10 head 11 heel 12 toe 13 crown 14 face 15 back 16 neck 20 shaft 22 nominal shaft section 24 intermediate shaft section 26 offset shaft section 28 shaft indexing structure 30 shaft coupling, first embodiment 32 socket 34 coupling fitting, first embodiment 36 socket indexing structure 38 fitting indexing structure 50 hosel 52 hosel indexing structure 60 fastener 62 hole, hosel 64 threaded hole 70 hosel axis 72 nominal shaft axis 74 socket axis 76 offset shaft axis 105 offset shaft and coupling apparatus, second embodiment 110 head, second embodiment 116 neck, second embodiment 120 shaft, second embodiment 122 nominal shaft section, second embodiment 123 bushing 124 bushing cavity 126L offset shaft section lower portion 126U offset shaft section upper portion 127 shaft cavity 128 bushing indexing structure 130 skewed shim shaft coupling 131 skewed shim 134 coupling fitting, second embodiment 138 fitting indexing structure, second embodiment 139 shim indexing structure 150 hosel, second embodiment 152 neck indexing structure

DESCRIPTIONFIG. 1OFFSET SHAFT AND COUPLING APPARATUS, FIRST EMBODIMENT

(7) FIG. 1, in an exploded view, shows a first assemblage which can provide any one of a plurality of possible golf club assemblies. The assemblage comprises a first embodiment of this invention, an offset shaft and coupling apparatus 5. The assemblage further comprises a head 10 which includes a heel 11, a toe 12, a crown 13, a face 14, a back 15, and a neck 16. Apparatus 5 comprises a shaft 20 which includes a nominal shaft section 22, an intermediate shaft section 24, and an offset shaft section 26. Nominal shaft section 22 embodies a shaft indexing structure 28. Apparatus 5 also comprises a shaft coupling 30 which includes a socket 32 located in a coupling fitting 34. Socket 32 embodies a socket indexing structure 36. Shaft coupling 30 includes a coupling indexing structure which, in this embodiment, is a fitting indexing structure 38 embodied in coupling fitting 34. Apparatus 5 further comprises a hosel 50, located in neck 16, which embodies a hosel indexing structure 52. Apparatus 5 further comprises a fastener 60, a hole 62 in hosel 50, and a threaded hole 64 in nominal shaft section 22. Hosel 50 is substantially symmetric with respect to a hosel axis 70, nominal shaft section 22 is substantially symmetric with respect to a nominal shaft axis 72, socket 32 is substantially symmetric with respect to a socket axis 74, and offset shaft section 26 is substantially symmetric with respect to an offset shaft axis 76.

OPERATIONFIGS. 1-5OFFSET SHAFT AND COUPLING APPARATUS, FIRST EMBODIMENT

(8) FIG. 1 shows how offset shaft and coupling apparatus 5 is able to provide for any one of the plurality of possible golf club assemblies. Socket 32, located in coupling fitting 34, is accepting of a portion of nominal shaft section 22, and hosel 50, located in neck 16, is accepting of a portion of coupling fitting 34. A shaft indexing mechanism comprises shaft indexing structure 28 and socket indexing structure 36 which can engage in a plurality of rotational positions of nominal shaft section 22 with respect to socket 32 in which their relative rotation is restrained. Also, a coupling indexing mechanism comprises fitting indexing structure 38 and hosel indexing structure 52 which can engage in a plurality of rotational positions of coupling fitting 34 with respect to hosel 50 in which their relative rotation is restrained. With nominal shaft section 22 in a chosen indexed rotational position in socket 32, and with coupling fitting 34 in a chosen indexed rotational position in hosel 50, fastener 60, by passing through hole 62 in hosel 50 and engaging threaded hole 64 in nominal shaft section 22, provides for coupling fitting 34 to be secured in hosel 50 and for nominal shaft section 22 to be secured in socket 32. Thereby shaft 20 is secured to head 10.

(9) The shaft adapter connection, discussed above, typically uses a fastener to secure the shaft adapter in the head's hosel, thereby allowing the shaft adapter to be readily secured in, and removed from, the hosel. But this connection typically employs an epoxy bond to secure the shaft in the shaft adapter's socket. Similarly, fastener 60 of apparatus 5 allows for coupling fitting 34 to be readily secured in, and removed from, hosel 50, but it also allows for nominal shaft section 22 to be readily secured in, and removed from, socket 32. Because of this difference, the term shaft coupling is chosen herein to name the device, namely shaft coupling 30, which connects shaft 20 to hosel 50. Just as in the descriptions above for shaft adapters, if shaft coupling 30, when secured in hosel 50, skews socket axis 74 with respect to hosel axis 70, then shaft coupling 30 is herein defined as being a skewed axis shaft coupling. Additionally, since coupling fitting 34, as shown in FIG. 1, skews socket axis 74 with respect to the component axis of rotation of shaft coupling 30 which is substantially co-linear with hosel axis 70, and since coupling fitting 34 is secured in hosel 50 directly against neck 16, shaft coupling 30 could furthermore be defined as being a skewed fitting shaft coupling. Therefore, similarly to skewed axis shaft adapters in prior art, shaft coupling 30 can provide for head 10 to have, with respect to nominal shaft section 22, a plurality of sets of angular properties such as loft angle, lie angle, and face angle.

(10) Nominal properties, as discussed above, are properties which are defined with respect to the hosel axis. In that vein, the word nominal was chosen in naming nominal shaft section 22 with its nominal shaft axis 72. Whether shaft coupling 30 is a skewed axis shaft coupling, as shown, or a straight axis shaft coupling, the average position of nominal shaft axis 72, which is the component axis of rotation, or reference axis, of shaft coupling 30, would be substantially co-linear with hosel axis 70.

(11) In addition to providing for head 10 to have a plurality of sets of angular properties with respect to nominal shaft section 22, apparatus 5 also provides for a plurality of sets of spatial and mass distribution properties of head 10 with respect to offset shaft section 26. Since offset shaft section 26 is offset from nominal shaft section 22, rotation of nominal shaft section 22 with respect to socket 32 moves offset shaft section 26 with respect to head 10. This movement changes several spatial and mass distribution properties that head 10 has with respect to offset shaft section 26, including its first and second moments of mass and its face progression.

(12) Offset shaft and coupling apparatus 5 is therefore similar in operation to the apparatus described in the U.S. Pat. No. 10,220,267 in that both provide for a golf club head to have a plurality of sets of spatial, mass distribution, and angular properties with respect to a shaft. The apparatus in U.S. Pat. No. 10,220,267 obtains its offset function by securing a skewed axis shaft adapter to a rotator such that the shaft adapter's reference axis is offset from an axis of rotation of the rotator. The present invention obtains its offset function by using intermediate shaft section 24 to locate the offset in shaft 20 itself.

(13) As shown in FIG. 1, the shaft indexing mechanism of apparatus 5, discussed above, provides four indexed rotationally restrained positions of nominal shaft section 22 in socket 32. FIG. 1 also shows that the coupling indexing mechanism provides four indexed rotationally restrained positions of coupling fitting 34 in hosel 50. These four sided indexing mechanisms were chosen by way of example, but other numbers of indexed rotationally restrained positions are possible, such as two, six, eight, or twelve.

(14) FIGS. 2 through 5 each show nominal shaft section 22 in one of its four indexed positions in socket 32. The position of shaft 20, shown in FIG. 2, in which the torque arm length of the COM of head 10 with respect to offset shaft section 26 is large relative to the nominal torque arm length, could be called a long torque arm position. Another suitable name would be high torque position because, when shaft 20 is in this position, accelerations of head 10 during a golf swing will cause head 10 to exert a relatively high torque on offset shaft section 26. Similarly, the position of shaft 20 shown in FIG. 3 could be called a short torque arm position, or a low torque position. Its position in FIG. 4 could be called a long face progression position, and its position in FIG. 5 a short face progression position. With shaft 20 in its long torque arm position or its short torque arm position, the face progression of club 10 is substantially equal to its nominal face progression. With shaft 20 in its long face progression position or its short face progression position, the torque arm length of the COM of head 10 with respect to offset shaft axis 76 is longer than the nominal torque arm length (think hypotenuse) by a relatively small amount, but it is considerably closer to nominal than when shaft 20 is in its long or short torque arm positions.

(15) In many cases, a construction of offset shaft and coupling apparatus 5 which includes three special conditions is beneficial. A first special condition is that shaft 20 has a construction in which offset shaft axis 76 is substantially parallel with nominal shaft axis 72. A second special condition for apparatus 5 is that its shaft indexing mechanism and its coupling indexing mechanism are constructed such that they provide for two indexed rotationally restrained positions of nominal shaft section 22 in socket 32 and coupling fitting 34 in hosel 50 wherein hosel axis 70, offset shaft axis 76, and the face line of head 10 are substantially co-planar. A third special condition, which normally is automatically met if the second special condition is met, is that these indexing mechanisms are constructed such that they also provide for two indexed rotationally restrained positions of nominal shaft section 22 in socket 32 and coupling fitting 34 in hosel 50 wherein offset shaft axis 76 and hosel axis 70 are substantially co-planar, and that plane is substantially perpendicular to the face line of head 10.

(16) A first benefit resulting from apparatus 5 having the special construction conditions is an independency in its adjustment ability. If apparatus 5 is so constructed, then with nominal shaft section 22 positioned in socket 32 and coupling fitting 34 positioned in hosel 50 as shown in FIG. 2, hosel axis 70, offset shaft axis 76, and the face line of head 10 are substantially co-planar. Furthermore, shaft 20 is in its long torque arm position, and head 10 has, with respect to offset shaft axis 76, a first set of spatial properties, a first set of mass distribution properties, and a set of angular properties. If nominal shaft section 22 is rotated 180 degrees in socket 32 to its short torque arm position while leaving coupling fitting 34 in its original rotational position with respect to hosel 50, these positions being shown in FIG. 3, head 10 has, with respect to offset shaft axis 76, a second set of spatial properties, a second set of mass distribution properties, but a set of angular properties which is substantially unchanged from the original set. Therefore, if apparatus 5 has a construction which includes the special conditions, apparatus 5 is able to provide for adjustments in the golf club's spatial and mass distribution properties while leaving its angular properties substantially unchanged, and vice versa.

(17) A second benefit resulting from apparatus 5 having the special construction conditions is a maximization of its ability to affect the spatial and mass distribution properties of head 10 with respect to offset shaft section 26. If shaft 20 has the first special construction condition wherein offset shaft axis 76 is substantially parallel with nominal shaft axis 72, shaft 20 can be said to have an offset dimension, herein defined as being a distance, measured perpendicularly, between these axes. If apparatus 5 also has the second special condition, then, for any given offset dimension of shaft 20, apparatus 5 is able to provide a maximum change in torque arm length of the COM of head 10 with respect to offset shaft axis 76 under a 180 degree rotation of nominal shaft section 22 in socket 32 from its long torque arm position to its short torque arm position. Similarly, if apparatus 5 includes the third special condition, this enables apparatus 5 to provide a maximum change in face progression of head 10 with respect to offset shaft axis 76 under a 180 degree rotation of nominal shaft section 22 in socket 32 from its long face progression position to its short face progression position.

(18) The discussions above, directed toward a simple golf club, concerning the first and second moments of mass of a golf club head with respect to a shaft are also applicable to this more complicated golf club which employs offset shaft and coupling apparatus 5. The first moment of mass of head 10 with respect to offset shaft axis 76 is the mass of head 10 times the torque arm length of the COM of head 10 with respect to axis 76. The mass of head 10 and accelerations in the golf swing apply torques around offset shaft axis 76 which have magnitudes determined by the accelerations and the first moment of mass of head 10 with respect to offset shaft axis 76. The COM of a typical golf club head, such as head 10, is located somewhat centered horizontally on, and slightly behind, its face, such as face 14 of head 10. Therefore, for any given golf swing, the torques applied about offset shaft axis 76 by head 10 are greater when shaft 20 is in the long torque arm length position, as shown in FIG. 2, than when it is in the short torque arm length position, as shown in FIG. 3. Torque application causes shaft 20 to twist, resulting in an opening or closing of face 14 of head 10 with respect to a target line. The second moment of mass of head 10 with respect to offset shaft axis 76 and a torsional stiffness of shaft 20 affect a torsional frequency of the opening and closing of face 14. This torsional frequency is lower when shaft 20 is in its long torque arm position, higher when in its short torque arm position, and in between when in other intermediate positions. Depending on acceleration magnitudes and their timing in a golfer's swing, his selection of the long torque arm length position, the short torque arm length position, or some intermediate position for shaft 20 can help him achieve a straight golf shot, or, if desired, one with a draw or a fade.

(19) A USGA equipment rule states except for putters, all of the heel portion of the club must lie within 0.625 inches (15.58 mm) of the plane containing the axis of the straight part of the shaft and the intended (horizontal) line of play. In order to comply with this rule, offset shaft axis 76 must never be farther than 15.58 mm (0.625) from heel 11, measured as described in this rule. When employed with typical golf club heads, apparatus 5 can meet this USGA rule with shaft 20 having an offset dimension of at least 7.6 mm (0.30 inches). Another USGA equipment rule states the shaft must be straight from the top of the grip to a point not more than 5 inches (127 mm) above the sole, measured from the point where the shaft ceases to be straight along the axis of the bent part of the shaft and the neck and/or socket. Shaft 20 can be constructed such that, even with driver heads that are relatively tall and with shaft 20 having an offset dimension of 7.6 mm (0.30 inches), a golf club which employs apparatus 5 will comply with this second rule.

(20) The word substantially, often used in these discussions, indicates that a feature which it is modifying, such as a dimensional or angular property, has some level of acceptable error. For instance, consider the angular relationship between nominal shaft axis 72 and offset shaft axis 76. The first special construction condition of apparatus 5 is that these axes are substantially parallel, implying that there is some acceptable, and indeed unavoidable, error in their parallelism. Even though an error of 0.25 degrees in the parallelism of nominal shaft axis 72 with respect to offset shaft axis 76 is readily attainable by those skilled in the art, an error of 0.5 degrees would probably be considered an acceptable error by many of these same people.

DESCRIPTION AND OPERATIONFIGS. 6 AND 7OFFSET SHAFT AND COUPLING APPARATUS, SECOND EMBODIMENT

(21) FIG. 6, in an exploded view, shows a second assemblage which can provide any one of a plurality of possible golf club assemblies. This assemblage comprises a second embodiment of this invention, an offset shaft and coupling apparatus 105. The assemblage further comprises a head 110 which is similar to head 10 except it has a neck 116 in which a hosel 150 is located, and these two features embody a neck indexing structure 152. Apparatus 105 is similar to apparatus 5 except for the following features. Apparatus 105 comprises a shaft 120 which includes a nominal shaft section 122 and a bushing 123. Bushing 123 includes threaded hole 64 and a bushing cavity 124, and it embodies a bushing indexing structure 128. Shaft 120 further includes intermediate shaft section 24, an offset shaft section lower portion 126L in which a shaft cavity 127 is located, and an offset shaft section upper portion 126U. Apparatus 105 further comprises a skewed shim shaft coupling 130 which includes two components, a skewed shim 131 and a coupling fitting 134. Skewed shim shaft coupling 130 includes a coupling indexing structure which, in this embodiment, comprises two indexing structures, a fitting indexing structure 138 embodied in coupling fitting 134 and a shim indexing structure 139 embodied in skewed shim 131.

(22) In apparatus 5, shaft indexing structure 28 and threaded hole 64 are an integral part of nominal shaft section 22. But in apparatus 105, bushing 123 is provided and is to be secured to nominal shaft section 122 using bushing cavity 124. Threaded hole 64 is located in bushing 123, and it provides for shaft 120 to be secured to coupling fitting 134 using fastener 60. When nominal shaft section 122 is secured in bushing cavity 124, bushing indexing structure 128 provides for nominal shaft section 122 to be restrained from rotation with respect to socket 32 of coupling fitting 134 in any one of a plurality of rotational positions. Potential benefits which may accrue from using bushing 123 include ease of manufacture and improved strength of nominal shaft section 122.

(23) In apparatus 5, shaft 20 has a one-piece construction which is particularly applicable if shaft 20 is constructed entirely of a metallic material which is readably bendable to form intermediate shaft section 24. In many golf clubs, however, it is advantageous to use a shaft which employs a carbon fiber in at least of a portion of its construction. To this end, shaft 120 of apparatus 105 incorporates a two-piece construction; a lower piece comprising nominal shaft section 122 with bushing 123, intermediate shaft section 24, and offset shaft section lower portion 126L, and an upper piece comprising offset shaft section upper portion 126U. It may be beneficial in some cases to use this two-piece shaft construction to allow, for instance, use of a metallic material to construct the lower piece and carbon fiber to construct the upper piece. Shaft cavity 127 provides for offset shaft section upper portion 126U to be secured to offset shaft section lower portion 126L by using, for instance, an epoxy bond.

(24) Apparatus 105 employs skewed shim shaft coupling 130 which functions similarly to the skewed shim shaft adapters discussed above. Skewed shim shaft coupling 130 includes a component, skewed shim 131, which has, circumferentially, a non-uniform thickness. Shim 131 embodies, on its opposing sides, shim indexing structure 139. One side of shim indexing structure 139 is engageable with neck indexing structure 152 and the other side is engageable with fitting indexing structure 138. As in skewed shim shaft adapters, these indexing structures provide for skewed shim 131 to be rotationally restrained in any one of a plurality of possible indexed rotational positions with respect to a component axis of rotation, or reference axis, which is typically substantially co-linear with hosel axis 70. This plurality of indexed rotational positions of skewed shim 131, along with its non-uniform thickness, provides for adjustment of the angular position of head 110 with respect to nominal shaft section 122, and hence provides for head 110 to have a plurality of available sets of angular properties with respect to nominal shaft section 122 and nominal shaft axis 72.

(25) Shaft 120 functions similarly to shaft 20 in that they both have an offset provided by intermediate shaft section 24. Bushing indexing structure 128, engageable with socket indexing structure 36, provides for nominal shaft section 122 to be rotationally restrained in any one of a plurality of possible indexed rotational positions with respect to socket axis 74. Thus, offset shaft axis 76 has a plurality of possible positions with respect to head 110, thereby providing for head 110 to have a plurality of possible sets of spatial and mass distributions properties with respect to offset shaft axis 76.

CONCLUSION, RAMIFICATIONS, AND SCOPE

(26) Accordingly, the reader will see that herein described is an offset shaft and coupling apparatus which, along with a head, provides for any one of a plurality of possible golf club assemblies. The apparatus comprises a shaft, having an offset between a nominal shaft section and an offset shaft section, and a shaft coupling, providing for the nominal shaft section to be secured to the head in a plurality of indexed rotationally restrained positions with respect to a socket of the shaft coupling. These features provide for the plurality of golf club assemblies to have a plurality of sets of spatial and mass distribution properties of the head with respect to the offset shaft section. Embodiments presented show two types of skewed axis shaft coupling, a skewed fitting shaft coupling and a skewed shim shaft coupling, whereby the apparatus further provides for the plurality of golf club assemblies to have a plurality of sets of angular properties of the head with respect to the nominal shaft section.

(27) Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of it. For instance, a single fastener is shown being used to secure both the shaft to the shaft coupling and the shaft coupling to the head. But two fasteners could be used, one fastener similar to the fastener shown which secures the shaft coupling to the head, and a second fastener, being either a screw or a nut, which secures the shaft in the socket. Also, the shaft couplings shown are of the skewed axis type, but use of a straight axis shaft coupling in some cases may be desirable. Also, the two embodiments presented have some individual features, but these features, in some cases, are interchangeable. For instance the bushing of the second embodiment could be attached to the one-piece shaft of the first embodiment. Also, the skewed fitting shaft adapter of the first embodiment could be used with the two-piece shaft of the second embodiment. The scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.