Abstract:
A releasable connection system for assembling a shaft and a club head, e.g., a golf club shaft and a golf club head. The connection system provides interchangeability between a shaft and a club head and allows the head to be adjusted with respect to the shaft. The mating structures between the shaft and the club head may be indexed for reproducible placement. In an embodiment, the connection system also includes retaining structures that maintain the connection fastener position when the head and shaft are separated.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 12/760,923, filed Apr. 15, 2010, currently pending, which is a continuation-in-part of U.S. patent application Ser. No. 11/958,412, filed Dec. 18, 2007, now U.S. Pat. No. 7,878,921, which is a continuation-in-part of U.S. patent application Ser. No. 11/734,819, filed Apr. 13, 2007, abandoned. Each of the listed applications are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention generally relates to golf clubs, and more specifically to golf clubs having an improved hosel connection that provides interchangeability and adjustability between a shaft and a club head. 
       BACKGROUND OF THE INVENTION 
       [0003]    In order to improve their game, golfers often customize their equipment to fit their particular swing. In the absence of a convenient way to make shafts and club heads interchangeable, a store or a business offering custom fitting must either have a large number of clubs with specific characteristics, or must change a particular club using a complicated disassembly and reassembly process. If, for example, a golfer wants to try a golf club shaft with different flex characteristics, or use a club head with a different mass, center of gravity, or moment of inertia, in the past it has not been practical to make such changes. Golf equipment manufacturers have been increasing the variety of clubs available to golfers. For example, a particular model of golf club may be offered in several different loft angles and lie angles to suit a particular golfer&#39;s needs. In addition, golfers can choose shafts, whether metal or graphite, and adjust the length of the shaft to suit their swing. Recently, golf clubs have emerged that allow shaft and club head components, such as adjustable weights, to be interchanged to facilitate this customization process. 
         [0004]    Golfers may also wish to adjust the loft angle, lie angle, or other trajectory setting of a club, for example to change the anticipated trajectory of a ball, as needed, in response to the topography of the course or the weather. For example, a golfer teeing off on a long dogleg may benefit from hitting a fade in order to land the ball in the center of the fairway. Alternatively, a golfer whose swing is reliably errant, e.g., due to an injury, may want to adjust the loft angle of the club in order to “straighten out” his or her swing. Such features are available in commercially-available clubs, such as clubs using MYFLY™ adjustable flight technology from Cobra Puma Golf (Carlsbad, Calif.). 
         [0005]    While the mechanics of adjustable and detachable heads are often similar, it is important that an adjustable head is reversibly engageable to the shaft so that the club head can be repeatedly adjusted without damaging the fastening mechanism. Furthermore, it is beneficial if the fastening mechanism is easy to operate (e.g., using a PGA-approved tool) and “dummy-proof”, i.e., it is difficult to lose the fastener or misalign the shaft when re-engaging. Additionally, a reversible fastening mechanism design should minimize the weight in the club head. If weight must be added, the weight preferably should be added toward the sole and back of the club head thereby allowing the center of mass to stay low in the club head. 
         [0006]    Examples of detachable/replaceable golf club heads include U.S. Pat. No. 3,524,646 to Wheeler for a Golf Club Assembly. The Wheeler patent discloses a putter having a grip and a putter head, both of which are detachable from a shaft. Fastening members, provided on the upper and lower ends of the shaft, have internal threads, which engage the external threads provided on both the lower end of the grip and the upper end of the putter head shank to secure these components to the shaft. The lower portion of the shaft further includes a flange, which contacts the upper end of the putter head shank, when the putter head is coupled to the shaft. This design produces an unaesthetic bulge at the top of the shaft and another unaesthetic bulge at the bottom of the shaft. 
         [0007]    Another example is U.S. Pat. No. 4,943,059 to Morell for a Golf Club Having Removable Head. The Morell patent discloses a putter golf club including a releasable golf club head and an elongated golf club shaft. The club head hosel has a plug containing a threaded axial bore. A threaded rod is retained on the connector portion of the shaft, and is threaded into the axial bore of the plug of the club head for operatively connecting the shaft to the head. 
         [0008]    Another example is U.S. Pat. No. 5,433,442 to Walker for Golf Clubs with Quick Release Heads. The Walker patent discloses a golf club in which the club head is secured to the shaft by a coupling rod and a quick release pin. The upper end of the coupling rod has external threads that engage the internal threads formed in the lower portion of the shaft. The lower end of the coupling rod, which is inserted into the hosel of the club head, has diametric apertures that align with diametric apertures in the hosel to receive the quick release pin. 
         [0009]    Another example is U.S. Pat. No. 5,722,901 to Barron et al. for a Releasable Fastening Structure for Trial Golf Club Shafts and Heads. The Barron patent discloses a bayonet-style releasable fastening structure for a golf club and shaft. The club head hosel has a fastening pin in its bore that extends diametrically. The head portion of the shaft has two opposing “U” or “J” shaped channels. The head end portion of shaft fastens on the hosel pin through axial and rotary motion. A spring in the hosel maintains this fastenable interconnection, but allows manually generated, axially inward hosel motion for quick assembly and disassembly. 
         [0010]    Another example is U.S. Pat. No. 5,951,411 to Wood et al. for a Hosel Coupling Assembly and Method of Using Same. The Wood patent discloses a golf club including a club head, an interchangeable shaft, and a hosel with an anti-rotation device. The hosel contains an alignment member with an angular surface that is fixed, by a stud, within the hosel bore. A sleeve secured on the shaft end forms another alignment arrangement element and is adapted to engage the alignment element disposed in the hosel bore. A capture mechanism disposed on the shaft engages the hosel to fix releasably the shaft relative to the club head. 
         [0011]    Another example is U.S. Publ. Pat. App. No. 2001/0007835 A1 to Baron for a Modular Golf Club System and Method. The Baron publication discloses a modular golf club including club head, hosel, and shaft. A hosel is attached to a shaft and rotation is prevented rotation by complementary interacting surfaces, adhesive bonding or mechanical fit. The club head and shaft are removably joined together by a collet-type connection. 
         [0012]    Another example is U.S. Pub. Pat. App. No. 2006/0105855 A1 to Cackett et al. for a Golf Club with Interchangeable Head-Shaft Connections. The Cackett publication discloses a golf club that uses a sleeve/tube arrangement instead of a traditional hosel to connect the interchangeable shaft to the club head in an effort to reduce material weight and provide for quick installation. A mechanical fastener (screw) entering the club head through the sole plate is used to secure the shaft to the club head. 
         [0013]    Still another example is U.S. Pat. No. 6,547,673 to Roark for an Interchangeable Golf Club Head and Adjustable Handle System. The Roark patent discloses a golf club with a quick release for detaching a club head from a shaft. The quick release is a two-piece connector including a lower connector, which is secured to the hosel of the club head, and an upper connector, which is secured to the lower portion of the shaft. The upper connector has a pin and a ball catch that both protrude radially outward from the lower end of the upper connector. The upper end of the lower connector has a corresponding slot formed therein for receiving the upper connector pin, and a separate hole for receiving the ball catch. When the shaft is coupled to the club head, the lower connector hole retains the ball catch to secure the shaft to the club head. Other published patent documents, such as U.S. Pat. No. 7,083,529 and U.S. Publ. Pat. App. Nos. 2006/0287125, 2006/0293115, 2006/0293116 and 2006/0281575, disclose interchangeable shafts and club heads with anti-rotation devices located there between. 
         [0014]    There remains a need in the art for golf clubs with an improved connection that provides a method for quickly and easily interchanging the shaft, removable weights and other attachments with the club head. 
       SUMMARY OF THE INVENTION 
       [0015]    The invention is directed to a releasable connection system for assembling a golf club. The inventive connection system provides interchangeability between a shaft and a club head that imparts minimal visual impairment and club mass fluctuation while optimizing customization. Additionally, compared to prior art designs, the disclosed invention reduces the club head weight required for an adjustable hosel. 
         [0016]    The invention describes systems for reversibly joining a club shaft to a club head, allowing the club head to be adjusted during the course of play. The system includes a fastener having a retaining shoulder that constrains movement of the fastener within the club head, thereby assuring that the fastener remains aligned with, e.g., a hosel opening, and that the fastener does not inadvertently leave the club head. In some embodiments, the club head comprises a retaining member that is added to the club head to maintain the position of the fastener. The retaining member may be constructed from a lightweight material, e.g., plastic, thereby reducing the weight necessary to maintain the position of the fastener. The system can be used with any type of club head/shaft system, however, it is beneficially used in a golf club such as a driver, hybrid, iron, or putter. The invention provides an additional advantage of ease of manufacture because a club head using the invention does not require casting an extension body to stabilize the hosel connector. 
         [0017]    Golf club heads and golf clubs comprising a fastener for a reversible engagement with a shaft are also disclosed. The golf clubs or golf club heads include a hosel, a fastener having a retaining shoulder, and a retaining member coupled to a hole in a heel opening of the club head. The hole is substantially aligned with the hosel and the retaining member keeps the fastener aligned with a mating structure at the end of the golf club shaft. In some embodiments, the retaining member is a slotted sleeve. In other embodiments, the retaining member is a clip having tabs that retain the clip in the hole. 
         [0018]    In another embodiment, the present invention includes a connection system that comprises a two-part hosel, wherein a first hosel part is connected to the shaft and a second hosel part is connected to the club head, and an anti-rotation device is disposed between the first and second hosel parts, and the anti-rotation device is located above the club head. The anti-rotation device can have a first serrated surface disposed on the first hosel part and a second corresponding serrated surface disposed on the second hosel part. The first and second serrated surfaces mate to minimize relative rotation between the shaft and the club head. 
         [0019]    In another embodiment, the connection system comprises a hollow sole insert affixed in a hosel bore proximate a sole of the club head, wherein a first key is disposed on an internally threaded distal end of the shaft and a second corresponding key is disposed on the sole insert. As a fastener is inserted through the sole insert and into the threaded distal end of the shaft to connect the shaft to the club head, the first and second keys mate with each other to minimize relative rotation between the shaft and the club head. 
         [0020]    In another embodiment, the connection system comprises a spring loaded bayonet mount, wherein the spring has a spring constant from about 5 pounds-force/inch to about 100 pounds-force/inch and wherein the spring loaded bayonet mount is located above the club head. The bayonet mount comprises at least one post disposed on the shaft and at least one corresponding channel disposed on a hosel of the club head and the bayonet mount further comprises a spring disposed within the hosel. The channel may have a reduced diameter section sized and dimensioned to releasably retain said post. Alternatively, the bayonet mount comprises two or more posts disposed on the shaft and two or more corresponding channels disposed on a hosel of the club head. 
         [0021]    In another embodiment, the connection system comprises a hosel rotatable connection comprising a first hosel sheath, a second hosel part and an anti-rotation device. The first hosel sheath is connected to the shaft; the second hosel part is preferably made integral to the club head, and an anti-rotation device is disposed between the first and second hosel parts, and the anti-rotation device is preferably located above the club head. The anti-rotation device can have a first serrated surface disposed on the first hosel sheath and a second corresponding serrated surface disposed on the second hosel part. The first and second serrated surfaces mate to minimize relative rotation between the shaft and the club head. The hosel sheath has distal internal threads that threadably mate with the external threads on the second hosel part connected to the club head to hide the anti-rotation device to preserve the esthetics of the club head. In another embodiment, the first rotatable hosel sheath is connected to the hosel. 
         [0022]    In another embodiment, the connection system comprises two or more legs of uneven lengths connected to the shaft. One of the legs is an affixing leg and the other leg is a non-affixing leg. Corresponding receiving areas are provided in the hosel. The two or more legs cooperate to minimize relative rotation between the shaft and the club head. The affixing leg preferably is threaded to the hosel. 
         [0023]    Preferably the threaded connections of the embodiments of the present invention comprise multiple parallel threads to maintain the thread count of the connection, thereby improving the strength of the connection, while minimizing the time required connecting the threaded connectors together. 
         [0024]    In another embodiment, the connection system comprises a wedge hosel connected to the shaft, a club head insert disposed within the club head and a wedge screw threaded to the wedge hosel through the heel of the club head to retain the wedge hosel to the club head and to the club head insert. The anti-rotation device comprises a first serrated surface disposed on the wedge hosel and a second corresponding serrated surface disposed on the club head insert. The wedge screw also minimizes club head rotation relative to the shaft. 
         [0025]    In another embodiment, the connection system comprises a bendable hosel, club head insert, and anti-rotation device. The bendable hosel is connected to the shaft, and the shaft-hosel assembly is connected to the club head via a screw. The connection system further comprises a cap disposed below the screw head to retain the screw within the club head during connection and disconnection. An anti-rotation device is also provided. 
         [0026]    A hosel insert adapted to change the loft and/or lie angle of the club is also provided. A dampener or spring can be placed within the connection system to minimize vibration during impacts. 
         [0027]    In another embodiment, the anti-rotation device comprises first tapered projections operatively connected to the shaft and second tapered projections operatively connected to the club head, wherein the first and second tapered projections are sized and dimensioned so that when the shaft is connected to the club head a gap is formed between at least some of the tapered projections and the shaft or club head. This gap assists the two projections to fit flush together when assembled. 
         [0028]    The inventive connection system may also comprise a threaded connection, wherein said threaded connection comprises a first threaded surface operatively connected to the shaft, a corresponding second threaded surface operatively connected to the club head and a helical coil insert adapted to fit between the first and second threaded surfaces. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views: 
           [0030]      FIG. 1  is an exploded view of an exemplary driver club showing a shaft, a club head and a first embodiment of the inventive connection system; 
           [0031]      FIG. 2  is an exploded view of the two-part hosel of the connection system of  FIG. 1 ; 
           [0032]      FIG. 3  is a perspective view of the assembled shaft; 
           [0033]      FIG. 4  is a partial cross-sectional view of the connection system of  FIG. 1 ; 
           [0034]      FIG. 5  is a perspective view of the assembled driver club of  FIG. 1 ; 
           [0035]      FIGS. 6 and 7  are perspective views another embodiment of the inventive connection system; 
           [0036]      FIG. 8  is an exploded view of an exemplary driver club and another embodiment of the inventive connection system;  FIGS. 8A and 8B  are alternatives of the embodiment of  FIG. 8 ; 
           [0037]      FIG. 9  is an exploded view of an alternative of the embodiment of  FIG. 8  illustrated with an iron club; 
           [0038]      FIG. 10A  is an exploded view of another embodiment of the inventive connection system;  FIG. 10B  is a perspective view of the assembled club head, sheath, shaft, and inserts of  FIG. 10A ;  FIG. 10C  is an exploded view of inner shaft insert, sheath, and outer shaft insert of  FIG. 10A ; and  FIG. 10D  is an exploded view of shaft inserts, sheath, and assembled shaft and club head of  FIG. 10A ; 
           [0039]      FIG. 11A  is an exploded view of another embodiment of the inventive connection system;  FIG. 11B  is a perspective view of the assembled club head, reverse sheath, shaft and insert of  FIG. 11A ;  FIG. 11C  is an exploded view of shaft insert and shaft of  FIG. 11A ; and  FIG. 11D  is an exploded view of iron insert, reverse sheath, and club head of  FIG. 11A ; 
           [0040]      FIG. 12A  is an exploded view of another embodiment of the inventive connection system;  FIG. 12B  is a perspective view of shaft insert of  FIG. 12A ;  FIG. 12C  is a partial rear, exploded hosel and club head of  FIG. 12A ;  FIG. 12D  is an exploded view of shaft and shaft insert of  FIG. 12A ; and  FIG. 12E  is a partial cross-sectional view of assembled iron club of  FIG. 12A ; 
           [0041]      FIG. 13A  is a force-flow through a set of threaded fasteners; and  FIG. 13B  is a single threaded right-hand and double threaded left-hand fastener; 
           [0042]      FIG. 14A  is a partial cross-sectional view of a club head adapted for use with another embodiment of the inventive connection system;  FIG. 14B  is an enlarged perspective view of a wedge hosel of  FIG. 14A ;  FIG. 14C  is an exploded view of shaft and wedge hosel;  FIG. 14D  is a perspective view of assembled shaft and wedge hosel of  FIG. 14A ;  FIG. 14E  is an enlarged perspective view of wedge screw; and  FIG. 14F  is a partial cross-sectional view of assembled club of this embodiment;  FIG. 14G  is a cross-sectional view of another embodiment of the wedge hosel;  FIGS. 14  H-I are top views of alternatives of the head of the wedge shown in  FIG. 14G ;  FIG. 14J  is a cross-sectional view of an alternative of the body of the wedge shown in  FIG. 14G ; 
           [0043]      FIG. 15A  is a partial cross-sectional view of a club head for use with another embodiment of the inventive connection system;  FIG. 15B  is a perspective view of a bendable hosel;  FIG. 15C  is an exploded view of the shaft, bendable hosel and shaft insert;  FIG. 15D  is an exploded view showing the club head of  FIG. 15A  and the assembled shaft and hosel of  FIG. 15C ; 
           [0044]      FIG. 16A  is an exploded view of  FIG. 15D  with a system for retaining the screw in the club head;  FIG. 16B  is a partial cross-sectional view of the assembled golf club;  FIG. 16C  is an enlarged perspective view of one embodiment of the retaining system;  FIG. 16D  is an enlarged cross-sectional view of the club head bore adapted to receive the retainer of  FIG. 16C ; and  FIG. 16E  is an enlarged perspective view of another embodiment of the retainer; 
           [0045]      FIG. 17A  is a partial cross-sectional view of a club head for use with another embodiment of the inventive connection system; and  FIG. 17B  is a partial cross-sectional view of the assembled golf club with a translucent window; 
           [0046]      FIG. 18A  is a perspective view of a club head of  FIG. 5  with an hosel insert; and  FIG. 18B  is an enlarged view perspective view of the hosel insert; 
           [0047]      FIGS. 19A-C  are perspective views of an alternative to the anti-rotation feature of the present invention;  FIG. 19D  is a schematic view of another serrated anti-rotation surfaces; and 
           [0048]      FIG. 20A  is a cross-sectional view of another embodiment of the present invention;  FIGS. 20B-C  are cross-sectional views of variations of the embodiment shown in  FIG. 20A ;  FIG. 20D  is a cross-sectional view of a damper/spring usable with the present invention; 
           [0049]      FIG. 21A  is an interior schematic view showing alignment of the fastener and the shaft secured in the hosel;  FIG. 21B  shows a close-up detail of the fastener with a retaining shoulder being held in position with a retaining member that is a sleeve having slots; 
           [0050]      FIG. 22  shows a screw having a retaining shoulder; 
           [0051]      FIG. 23  illustrates the principle whereby motion of a fastener having a retaining shoulder is restricted by a structure incorporated into a club head. The structure may be integrated into the club head, or it may be a separate retaining member such as shown in FIGS.  24 A,B and FIGS.  25 A,B; 
           [0052]      FIG. 24A  is a perspective view of an embodiment of a retaining member interfaced with a fastener having a retaining shoulder;  FIG. 24B  is a cross-sectional view of a fastener having a retaining shoulder, held in place by the retaining member of  FIG. 24A ; 
           [0053]      FIG. 25A  is a perspective view of an embodiment of a retaining member in a relaxed position prior to interfacing with a fastener or a club head;  FIG. 25B  is a cross-sectional view of a fastener having a retaining shoulder, held in place by the retaining member of  FIG. 25A . 
       
    
    
     DETAILED DESCRIPTION 
       [0054]    The present invention is directed to a quick connection system for connecting the shaft to a club head and for changing the shaft or the club head to optimize the golfer&#39;s strength to the playing conditions. Such a system can be utilized or customized for various applications, including, but not limited, to the shaft-club head connection, the insertion of adjustable weights in the club head, and the connection of a sole plate to the club head. The invention can also be used to change the trajectory properties of the golf club, e.g., by changing the loft angle. Several embodiments of the present invention are described below. In some embodiments, the designs offer improved functionality and weight savings. 
         [0055]    Inventive connection system  10  is designed for club fitters to repeatedly change shaft or club head combinations during a fitting session. Inventive connection system  10  is designed to give fitting accounts maximum fitting options with a system that is fast and easy to use. Referring to  FIGS. 1 and 2 , connection system  10  releasably connects club head  12  to shaft  14 , such that different shafts  14  can be connected to different club heads  12 . Connection system  10  comprises a two-part hosel, i.e., shaft serrated hosel  16  and driver serrated hosel  18  and internally threaded shaft insert  20 . Serrated surface  17  of shaft hosel  16  and serrated surface  19  driver hosel  18  are sized to mate with each other to minimize or prevent relative rotation between shaft hosel  16  and driver hosel  18 . Preferably, each serrated surface comprises a plurality of corresponding teeth. Connection system  10  further comprises driver sole insert  22  and screw  24 , which are connected to club head  12  on the sole side, as shown. As best shown in  FIG. 3 , shaft  14  is at least partially hollow and is sized and dimensioned to receive and retain internally threaded shaft insert  20  therewithin. Preferably, shaft insert  20  is securely attached to shaft  14  by means of adhesives, epoxies or similar materials. Shaft serrated hosel  16  is sized and dimensioned to fit on the outside of shaft  14 . A predetermined length  26  of shaft  14  is positioned below shaft serrated hosel  16  for insertion into club head  12 . The internal threads of shaft insert  20  are adapted to receive the external threads of fastener  24 , such as screw  24 . 
         [0056]    As best shown in  FIG. 4 , driver serrated hosel  18  has external threads, as shown, and is threaded into the top of bore  28  of club head  12 . Adhesives or epoxies can also be used to affix driver serrated hosel  18  to bore  28 . At the bottom of bore  28 , driver sole insert  22  is inserted into bore  28  and affixed therein. Preferably, driver sole insert  22  is serrated or threaded on the outside surface to increase the surface area to adhesives or epoxies. The assembled shaft  14  with shaft insert  20  and shaft hosel  16  as shown in  FIG. 3  is inserted through driver hosel  18  and into bore  28 . Screw  24  is inserted through driver sole insert  22  and is threaded into shaft insert  20  to secure shaft  14  to club head  12 . Preferably, distal tip  30  of shaft  14  is spaced apart from the top of driver sole insert  22  and shaft  14  and driver sole insert  22  is separated by gap  32 . Gap  32  ensures that screw  24  can fully pull shaft  14  downward toward the sole of club head  12  so that serrated surfaces  17  and  19  fully engage each other to minimize relative rotation between the two hosels  16  and  18  thereby minimizing relative rotation between shaft  14  and club head  12 . In other words, gap  32  ensures that screw  24  does not “bottom out” inside threaded shaft insert  20  so that serrated hosels  16  and  18  can fully mate with each other. 
         [0057]    Optionally, bore  28  has ledge  34  shown in  FIG. 4  formed integrally thereon, e.g., through the casting process, to abut driver sole insert  22  to provide additional structural support for driver sole insert  22  and screw  24 . Alternatively, driver sole insert  22  can be formed integrally on bore  28 . These alternatives are applicable to all of the embodiments described herein. Referring to  FIG. 5 , a fully assembled golf club is shown. Serrated hosels  16  and  18  form a single hosel and the serrated lines  17  and  19  separating the two hosels are preferably located above the top of club head  12 . The advantage of locating the anti-rotation device, i.e., shaft serrated hosel  16  and driver serrated hosel  18 , above the club head is that no additional mass is added, thereby preserving the mass properties of the club head and eliminating a protrusion at the shaft/hosel intersection. The anti-rotation device uses a standard hosel to make both the shaft serrated hosel and the driver serrated hosel. This means there is no weight gained or lost from the device, which in turn means no change in moment of inertia or center of gravity. Furthermore, serrated lines  17  and  19  add a visual distinction to the golf club and readily identify the golf club as an interchangeable golf club. 
         [0058]    Driver sole insert  22  and shaft threaded insert  20 , as well as hosel insert  16  and/or hosel insert  18 , can be made out of aluminum, stainless steel or titanium. Screw  24  can be any threaded screw, and is preferably a TORX™ drive flat head screw and the sole insert  22  is tapered so that the head of screw  24  can be flushed with sole insert  22 , as best shown in  FIG. 4 . 
         [0059]    Referring to  FIGS. 6 and 7 , another embodiment of connection system  10  is shown. In this embodiment, the two-part hosel of the first embodiment is replaced by a keyed anti-rotation device. This keyed anti-rotation device comprises angled cut-out  36  on the distal tip of shaft  14 . Shaft  14  is also hollow and has threaded shaft insert  20  inserted therein and conventional hosel  40  disposed thereon. Driver sole insert  22 ′ has angled surface  38  sized and dimensioned to match cut-out  36 . In this embodiment, shaft  14  is inserted into driver sole insert  22 ′, and angled cut-out  36  is keyed to angled surface  38  as screw  24  is threaded into shaft insert  20  to minimize or prevent relative rotation between shaft  14  and driver sole insert  22 ′/club head  12 . An advantage of this embodiment is that an anti-rotation device can be added without adding substantial weight to the club head thereby minimizing the effect on the club&#39;s swing weight. Referring to  FIG. 8 , another embodiment of connection system  10  is shown. In this embodiment, bore  28  does not extend through club head  12 . Club head  12  has hosel  42 , which has at least one and preferably two or more channels  44 . Channel  44  has entry leg  46  and locking leg  48 . Leg  46  is adapted to receive post  50  on shaft  14 . After post  50  travels through entry leg  46 , it passes transverse leg  47  before being received and held in locking leg  48 . Disposed within hosel  42  is spring  52  that exerts an upward force on shaft  14  to hold securely post  50  in locking leg  48 . Spring  52  is selected so that it can exert a sufficient force to hold post  50  within channel  44 . Preferably, spring  52  has a spring constant from about 5 to about 100 pounds-force/inch. More preferably, the spring constant can be in the range of about 20 to about 75 pounds-force/inch and most preferably about 33 pounds-force/inch. A golfer can conveniently insert shaft  14  into hosel  42  after aligning post  50  to leg  46 . Thereafter, shaft  14  is rotated along transverse leg  47  and afterward spring  52  pushes shaft  14  up locking leg  48 . Post  50  and channel  44  is also known as a bayonet mount or connection. 
         [0060]    Although channel  44  is illustrated as a “J-shaped” channel, it can have any shape, e.g., “U”, “L”, “S”, “V” or “W” shape. Also, preferably leg  46  is preferably deep so that as post  50  is moved down into hosel  42 , more of shaft  14  overlaps hosel  42  to increase mechanical stability. Alternatively, the top of locking leg may have a reduced diameter section to hold post  50  by press-fit or by increased friction. As illustrated in  FIG. 8A , the reduced diameter section can be a triangular section. The reduced diameter section can also be a figure-eight or waist section. In another embodiment, shown in  FIG. 8B , the connection system provides adjustability of an angular attribute of golf club head  12  relative to shaft  14 , such as face angle, loft and lie. Similar to previous embodiments, club head  12  includes hosel  42 , but in the present embodiment, hosel  42  has at least two channels  44  so that the shaft may be positioned in at least two discrete orientations relative to head  12 . For example, shaft  14  may be coupled to hosel  42  in a first orientation and in a second orientation in which the shaft is rotated about a longitudinal axis of hosel  42  from the first orientation. Channels  44  are spaced circumferentially around hosel  42  and each channel  44  has entry leg  46  and locking leg  48 . 
         [0061]    Shaft  14  includes a distal engagement portion  43  and a proximal portion that extends from the distal portion to a grip end of shaft  14 . In an assembled golf club, engagement portion  43  is at least partially received in hosel  42  and coupled thereto. The engagement portion may comprise a separate sleeve component that is attached to shaft  14  or it may be formed as an integral part of shaft  14  during the manufacture. Engagement portion  43  is a generally elongate portion of shaft  14  that is shaped to engage hosel  42  and defines a longitudinal axis A. The engagement portion of shaft  14  defines a longitudinal axis B that is angled relative to axis A by an angular offset θ. By providing at least two discrete orientations of shaft  14  relative to head  12  and angular offset θ, an angular attribute of club head  12  relative to shaft  14  may be altered. Preferably, the angular offset θ ranges from about 0.5° to about 5.0°. At least one post  50  is included on engagement portion  43 . Post  50  extends radially outward from an outer surface of engagement portion  43  and is configured to engage channel  44 . Preferably, shaft  14  includes the same number of posts  50  as channels  44 . For example, in an embodiment that includes two channels circumferentially spaced about the hosel by 180° also, preferably includes two posts circumferentially spaced about the engagement portion by 180°. In the present embodiment, post  50  is a screw that engages a threaded bore in engagement portion  43  and is therefore movably coupled to engagement portion  43 . 
         [0062]    In channel  44 , leg  46  is adapted to receive post  50  on shaft  14 . After post  50  travels through entry leg  46 , it passes transverse leg  47  before being received and held in locking leg  48 . Disposed within hosel  42  is spring  52  that exerts an upward force on shaft  14  to hold securely post  50  in locking leg  48 . Spring  52  is selected so that it can exert a sufficient force to hold post  50  within channel  44 . Additionally, the top of locking leg may include a receptacle  49  that receives a portion of post  50  to prevent relative motion between shaft  14  and club head  12  when post  50  is fully engaged in channel  44 . For example, the screw may be configured to lock into receptacle  49  when the screw is tightened, such as by forming receptacle as a countersunk portion of locking leg  48  and engaging it with a countersunk screw head. 
         [0063]      FIG. 9  illustrates another variation of the embodiment of  FIG. 8 , where hosel  42  has two or more channels  44 . Channels  44  can have the shapes or configurations of those described in  FIGS. 8 and 8A . An advantage of this embodiment is that having two or more locking legs  48  prevents twisting at the lower end of the leg and it offers a back up should one of the locking legs  48  fail. 
         [0064]    Referring to  FIGS. 10A to 10D , another embodiment of connection system  10  comprises a first rotatable hosel sheath  70  with internal threads and a second threaded, hollow hosel part  72 , which is fixedly attached to club head  74 . Preferably, second threaded hosel part  72  is made integral to club head  74 , and hosel sheath  70  and hosel part  72  are sized and dimensioned to threadably attach to each other to connect shaft  14  to club head  74 . Connection system  10  further comprises an anti-rotation device, made up of first serrated surface  76  disposed on inner shaft insert  80  and corresponding second serrated surface  78  disposed on second threaded hosel part  72 . 
         [0065]    To assemble the club, upper end  82  of inner shaft insert  80  is inserted into the threaded end of rotatable hosel sheath  70 , as shown in  FIG. 10C . End  82  is sized and dimensioned to pass through aperture  84  of hosel sheath  70 , but the top portion of serrated surface  76  is retained within hosel sheath  70 . End  82  is then inserted into aperture  86  and finally attached to outer shaft insert  88 . After end  82  of inner shaft insert  80  is fixedly connected to outer shaft insert  88 , there is sufficient clearance for first hosel sheath  70  to be freely rotatable to connect to second hosel part  72 . Preferably, the length of end  82  is dimensioned so that once end  82  is fully inserted into aperture  86 , there remains sufficient clearance between outer shaft insert  88  and hosel sheath  70  for hosel sheath  70  to rotate freely. Outer shaft insert  88  is then inserted into shaft  14 . Alternatively, inner sheath insert  80  is inserted into and attached directly to shaft  14  and outer sheath insert  88  can be omitted. 
         [0066]    Although this embodiment of the present invention is particularly suited to hosel sheath  70  made of metal, hosel sheath  70  can be made of high impact transparent or translucent materials. Suitable materials include, but are not limited to, polymethacrylate, cellulose acetate butyrate, polycarbonate (Lexan®), and glycol modified polyethylene teraphthalate. Afterward, as shown in  FIG. 10D , shaft  14 , with decorative ferrule  90 , hosel sheath  70  and both shaft inserts  80  and  88 , is assembled with club head  74 . More specifically, lower end  83  of inner shaft  80  is inserted into second hosel part  72  to allow corresponding threads of hosel sheath  70  and hosel part  72  to mate and connect shaft  14  to club head  74 . End  83  may extend partially or fully into club head  74 . Serrated surfaces  76  and  78  also mate to minimize relative rotation between the shaft and the club head. 
         [0067]    Referring to  FIGS. 11A to 11D , another embodiment of connection system  10  comprises a rotatable hosel reverse sheath  92  with internal threads and a threaded, hollow shaft insert  94 , which is fixedly attached to shaft  14 . Hosel reverse sheath  92  and shaft insert  94  are sized and dimensioned to threadably attach to each other to connect shaft  14  to club head  98 . Connection system  10  further comprises an anti-rotation device, made up of first serrated surface  100  disposed on club insert  102  and corresponding second serrated surface  104  disposed on shaft insert  94 . 
         [0068]    To assemble the club, upper end  96  of shaft insert  94  is inserted into and fixedly connected to shaft  14  for example by adhesive or epoxy, as shown in  FIG. 11C . Preferably, the length of end  96  is dimensioned so that there is a sufficient bond between shaft insert  94  and shaft  14 . Threads  106  and second serrated surface  104  should remain outside of shaft  14  and next to decorative ferrule  108 . 
         [0069]    As shown in  FIG. 11D , lower end  110  of club insert  102  is inserted into reverse sheath  92 . End  110  is sized and dimensioned to pass through aperture  112  of reverse sheath  92 , but the bottom portion of serrated surface  100  is retained within rotatable reverse sheath  92 . End  110  is then inserted into hosel  114  and is attached thereto. End  110  may extend partially or fully into club head  98  so long as there is sufficient clearance for reverse sheath  92  to rotate freely. To assemble the club, the assembled version of  FIG. 11C  is inserted into the assembled version of  FIG. 11D . Serrated surfaces  100  and  104  mate to minimize relative rotation between the shaft and the club head and reverse hosel sheath  92  is rotated so that its internal threads mate with threads  106  of shaft insert  94  to connect club head  98  to shaft  14 . 
         [0070]    Referring to  FIGS. 12A to 12E , another embodiment of connection system  10  comprises hollow shaft insert  54  connecting shaft  14  to club head  56 . Shaft insert  54  comprises affixing leg  57  and non-affixing leg  58 , which have uneven lengths, as best shown in  FIG. 12B . Hosel  55  has receiving area  59  adapted to receive shaft insert  54 . 
         [0071]    To assemble the club, shaft tip  60  is maintained below decorative ferrule  61  disposed on shaft  14 , as shown in  FIG. 12D . Upper end  62  of shaft insert  54  is inserted into shaft tip  60 , and shaft insert  54  is fixedly attached to shaft  14 . 
         [0072]    Afterward, as shown in  FIG. 12E , shaft  14 , with decorative ferrule  61  and shaft insert  54  is assembled with club head  56 . Specifically, lower end  63  of shaft insert  54  is inserted into receiving area  59  to connect shaft  14  to club head  56 . More specifically, affixing leg  57  is inserted into aperture  64  and threadably attached to sole nut  65  in bore  66  of club head  56 , while non-affixing leg  58  is mated to receiving area  59  to minimize relative rotation between the shaft and the club head. Preferably, non-affixing leg  58  is conical, wedge, or other key shape. Referring to  FIGS. 1 to 12E  and  14 A to  15 G, the embodiments of the present invention are illustrated with various single thread fasteners. These fasteners can be right-handed or left-handed and can have single thread or multiple threads. These fasteners need to be sufficiently strong to withstand repeated impacts between the golf club and the balls. An impact can create a force of up to 2,000 lbs. and depending on the location of the impact on the hitting face, connection system  10  may experience a torque load of 2,000·x, where x is a distance between the impact location and the neutral axis of the club. For example, a toe impact would produce more torque than a center impact. A heel impact would produce more torque (reverse direction) than a center impact. The density of threads and the dimensions of the threads should be designed to withstand the torque produced by toe and heel impacts. 
         [0073]      FIG. 13A  illustrates the force-flow lines  120  through a set of threaded fasteners used to clamp two members together. (Further detail can be found in  Fundamentals of Machine Component Design  by Robert C. Juvinall, copyright 1983, by John Wiley &amp; Sons, Inc.) Direct compressive stress, often called bearing, exists between threaded fastener  122  and corresponding fastener  124 . Stress (a) is defined as load (P)  128  divided by the cross sectional area (A)  130  that exists when the load is acting: σ=P/A. In this particular situation, the area used for the P/A stress calculation is projected area  132  that, for each thread, is π(d 2 −d i   2 )/ 4 , where d  134  is outer diameter of fastener cylinder and d i    136  is inner diameter of fastener  122  contact with nut  124 . The number of threads in contact is t/p, where t is fastener length of engagement  138  and p is fastener thread pitch, typically reported as inches per thread turn. (In practice, thread pitch is known by its reciprocal of threads per inch.) By substitution, σ=(4P/π(d 2 −d i   2 ))·p/t. This equation demonstrates the advantage of more threaded contacts in the present invention, which is the strength of a set of threaded fasteners is proportionately increased by increasing the threaded fastener contacts. Preferably, fastener threads per inch is 12 to 36 threads/inch. More preferably, fastener threads per inch is 18 to 30 threads/inch and most preferably 24 threads/inch. Increasing fastener contacts could increase the golfer&#39;s fastener tightening and untightening time, which is undesirable to a method for quickly and easily interchanging the shaft, removable weights and other attachments with the club head. Typically, threaded fasteners comprise a single helical groove  140  disposed on a cylindrical rod from end thread  142 , however if the helix angle  144  is increased other threads may be cut between the grooves of the first thread, so fasteners can have two  146  or more parallel threads, as shown in  FIG. 13B . (Further detail can be found in  Fundamentals of Machine Component Design  by Robert C. Juvinall, copyright 1983, by John Wiley &amp; Sons, Inc.) A fastener thread is assumed to be single thread, unless otherwise stated. Lead is the distance a threaded fastener advances axially in one turn. On a single threaded fastener  140 , the lead  148  and pitch  150  are identical; on a double thread fastener  146 , the lead  152  is twice the pitch  154 , etc. The end result is that the threaded fastener will advance twice as far in a single turn on a double thread fastener than it would on a single thread fastener, etc., so double, triple, or more threads are used whenever rapid advance is desired. The advantage of multiple parallel threads is that the thread count of the fastener connection can be increased to strengthen the fastener connection while minimizing the golfer&#39;s time to connect the threaded connectors together. Preferably, fasteners will be multiple thread and have the same direction. More preferably, fasteners will be double thread and have the same direction. Referring to  FIG. 13B , a thread may be either right-hand  140  or left-hand  146 . Almost all threaded fasteners tighten, or move away from the viewer, when rotated clockwise; a left-hand thread advances when turned counterclockwise. A fastener thread is assumed to be right-hand unless otherwise stated. During use of an assembled golf club, swinging the golf club and hitting the ball tends to tighten or loosen threaded connections, depending on whether the club is right- or left-handed and whether the thread is right- or left-hand. For right-handed golf clubs, left-hand threading would tighten during ball striking; for left-landed golf clubs, right-hand threading would tighten during ball striking. Preferably, fastener threading would be matched to loosening and tightening needs, so that the club can be readily assembled and disassembled before and after use. 
         [0074]    Referring to  FIGS. 14A to 14E , another embodiment of connection system  10  comprises a wedge hosel  160  with tapered receiving area  162 , a hollow club head insert  164  that is fixedly attached to club head  166 , and a wedge screw  168  with a first smooth tapered end  170  and a second threaded cylindrical end  172 . Tapered receiving area  162  of wedge hosel  160  is adapted to receive tapered head  170  of wedge screw  168 . Connection system  10  further comprises an anti-rotation device, made up of first serrated surface  174  disposed on wedge hosel  160  and corresponding second serrated surface  176  disposed on club head insert  164 . Additionally, when tapered head  170  is inserted into receiving area  162 , tapered head  170  also minimizes relative rotation between club head  166  and shaft  14 . Wedge screw  168  is preferably aligned substantially perpendicular or orthogonal to the shaft. 
         [0075]    To assemble the club, shaft tip  178  is maintained below decorative ferrule  180  disposed on shaft  14 , as shown in  FIG. 14C . Upper end  182  of wedge hosel  160  is sized and dimensioned to fit on the outside of shaft  14 , and wedge hosel  160  is fixedly attached to shaft  14  by means of adhesives, epoxies or similar materials. Shaft tip  178  is retained within wedge hosel  160 , as shown in  FIG. 14D . Preferably, upper end  182  of wedge hosel  160  is flush with decorative ferrule  180 . 
         [0076]    Club head insert  164  is inserted the top of bore  184  of club head  166  and affixed therein with diametric aperture  186  of club head insert  164  aligned with threaded side aperture  188  of club head  166 . Preferably, club head insert  164  is serrated or threaded on its outside surface to increase the surface area to adhesives or epoxies. Alternatively, club head insert  164  is made integral to club head  166 . 
         [0077]    Thereafter, shaft  14  and wedge hosel  160  assembly, as shown in  FIG. 14F , is inserted the top of bore  184  of club head  166 . The interaction of serrated surfaces  174  and  176  of wedge hosel  160  and club head insert  164  directs shaft  14  within bore  184  so that tapered receiving area  162  of wedge hosel  160  aligns with side aperture  188  of club head  166 . Tapered end  170  of wedge screw  168  is inserted through side aperture  188  of club head  166  into receiving area  162  of wedge hosel  160  and threaded end  172  of wedge screw  168  is releasably fastened into threaded side aperture  188  of club head  166 . 
         [0078]    Wedge  168  may comprise two components: wedge shell  169  and threaded fastener  171 , as shown in  FIGS. 14G-J . Fastener  171  fits within wedge shell  169  and is rotatably connecting hosel  160  to club head  12 . The two-component wedge is similar to the one-component wedge, except that the threads are located on the inner threaded fastener  171  and wedge shell  169  has substantially smooth outer surface to fit snugly to receiving area  162 . The end of wedge shell  169  can be conical, as shown in  FIG. 14H  or tapered, as shown in  FIG. 14I . The conical end has an advantage of self-centering as two component wedge  168  is being inserted into hosel  160 . The tapered end has an advantage of providing an anti-rotation tendency between wedge  168  and hosel  160 . Alternatively, wedge housing  169  can have a cylindrical outer shape as shown in  FIG. 14J . In the cylindrical embodiment, all of outer surface  173  is in contact with hosel  160  to provide enhanced contact between these two parts. A cover  175  is optionally provided to keep wedge  168  free of debris. 
         [0079]      FIGS. 15A to 15D  illustrate another embodiment of connection system  10  with a bendable hosel  190 . Hosel  190  is designed to bend preferable at section  192 , where the outer diameter of hosel  190  has a substantial change. Hosel  190  can be bent about section  192  to change the loft and/or lie angle of the golf club. Any bendable hosel with predetermined bends or any hosel with a weakened section can be used. Hosel  190  can be bent by automatic/motored or hydraulic bending tools, commonly used in golf pro shops, e.g., Steelclub Angle Machine sold by Mitchell Golf Equipment Co., and those used to bend pipes in the plumbing art. Suitable bendable hosels are disclosed in commonly owned, co-pending U.S. patent application Ser. No. 11/621,754, filed on Jan. 10, 2007, which is incorporated herein by reference in its entirety. Hosel  190  should be bendable only by equipment made for bending hosels, and not by impact with golf balls. 
         [0080]    Similar to the embodiment in  FIGS. 14A-14F , this connection system also has an anti-rotation device comprising a first serrated surface  194  on the hosel and a corresponding second serrated surface  196  on hollow club head insert  198 . To assemble the golf club, shaft insert  200  with internal threads in first inserted into shaft  14 , and then bendable hosel  190  is attached to the outside of shaft  14 , as shown in  FIGS. 15C-15D . The shaft and hosel assembly is then inserted into club head  202 . A screw  204  is inserted into heel opening  206  of club head  202  and is threaded into shaft insert  200  to retain shaft  14  to club head  202 , similar to the retaining mechanism shown in  FIGS. 1-4  and described above. 
         [0081]      FIGS. 16A-16E  illustrate a system for retaining screw  204  within club head  202  during the changing of hosel or club head. The connection system shown in  FIG. 16A  is similar to that shown in  FIG. 15D , except for hollow screw cap  208 . After screw  204  is inserted into heel opening  206 , as discussed in the preceding paragraph, screw cap is inserted into heel opening  206  and is sized and dimensioned to be positioned at a predetermined distance, l, below the top of screw  204 , as best shown in  FIG. 16B . Distance l is preferably greater than the depth of the teeth of serrated surfaces  194  and  196 . When a user wishes to change the hosel or club head, the user would insert a screwdriver to similar tool into heel opening  206 , through hollow screw cap  208  to the top of screw  204 . The user would then unscrew screw  204  to move screw  204  a distance l, or until the top of screw  204  comes into contact with screw cap  208 . At this point, the user can pull shaft  14  upward to disengage first serrated surface  194  of hosel  190  from the corresponding second serrated surface  196  of club head insert  198 . The user then can freely rotate shaft  14  relative to club head  202  to separate shaft  14  from club head  202 . The advantage of using screw cap  208  is that screw  204  is kept within the club head and the chance of misplacing screw  204  is minimized. 
         [0082]    Screw cap  208 , as shown in  FIG. 16C , may have waist  210 , and heel opening  206  may have at least one ledge  212 , as shown in  FIG. 16D , adapted to be received within waist  210  to keep screw cap  208  securely within the club head. Alternatively, as shown in  FIG. 16E  may have one or more protrusions  214 , as shown in  FIG. 16E , to provide an interference fit between screw cap  208  and the walls of heel opening  206 . 
         [0083]    In another embodiment, the club head may have an opening  216  formed on its heel as shown in  FIG. 17A . Opening  216  is adapted to receive a high impact transparent or translucent cap  218 , which allows the user to view the mechanisms of connection system  10 , as best shown in  FIG. 17B . Suitable materials include, but are not limited to, polymethacrylate, cellulose acetate butyrate, polycarbonate (Lexan®), and glycol modified polyethylene teraphthalate, discussed above. 
         [0084]    Another way to change the lie and/or loft angle of the golf club is illustrated in  FIGS. 18A and 18B . Here, golf club  10  which includes club head  12 , shaft  14  and hosel parts  16  and  17 , shown above in  FIG. 5 , has hosel insert  220  disposed between hosel parts  16  and  17 . Hosel insert  220  have serrated surfaces on its top and bottom to match the serrated surfaces of hosel parts  16  and  17 , so that hosel insert  220  would fit flush in between. To change the loft/lie angle of club  10 , first side  222  and second side  224  of hosel insert  220  are different from each other, or top line  226  is not parallel to bottom line  228 , as illustrated by lines  226 ′ and  228 ′. In other words, hosel insert  220  is askew. In one example, if first side  222  is shorter than second side  224 , then
       angle α&gt;angle β
 
and α=91° and β3=90°, then the shaft angle has been shifted by 1°. If the shaft coincides with the vertical axis then the shaft would have been shifted toward first side  222  by an amount equal to
   |90°−β|+|90°−α|       
 
         [0087]    In this example, if first side  222  and second side  224  are oriented in the toe-heel direction, then hosel insert  220  can change the lie angle. If first side  222  and second side  224  are oriented in the front-rear direction, then hosel insert  220  can change the loft angle. It is noted that hosel insert  220  does not need to have the serrated top and bottom surfaces as shown, so long as these surfaces match the corresponding surfaces on hosel parts  16  and  17 . For example, if the corresponding surfaces of hosel parts  16  and  17  are linear or curvilinear, then the top and bottom surfaces of hosel insert  220  can assume the same shape. Furthermore, hosel insert  220  can be positioned above club head  12 , as shown; however, it can also be located inside the club head. 
         [0088]    Furthermore, one of the hosel parts, can be made integral with club head  12 , as illustrated in  FIG. 20A . The hosel parts are preferably made from low density aluminum so that more mass can be distributed elsewhere to improve inertia and center of gravity properties.  FIG. 20A  is similar to  FIGS. 1-5  and is illustrated with similar reference numbers. As shown, hosel part  18  is made integral to club head  12  and matching serrated surfaces  17  and  19  are positioned above club head  12 , similar to the view shown in  FIG. 5 . Furthermore, hosel insert  220 , shown in  FIGS. 18A-B , can be used with this embodiment to change the lie and loft angle without bending the hosel. Alternatively, as shown in  FIG. 20B , matching serrated surface  17  and  19  are positioned internal to club head  12 . In this embodiment, serrated surface  19  may be formed directed on club head  12  during the casting process, and hosel part  18  can be omitted. Also, threaded shaft insert  20  can be omitted, when hosel insert  16  has threaded internal surface  238 , sized and dimensioned to receive screw  24  to attach hosel  14  to club head  12 , as shown in  FIG. 20C . An advantage of this embodiment, is that it has fewer parts than the embodiments shown in  FIGS. 20A and 20B  and that instead of the smaller contact surface between shaft insert  20  and hosel  14 , a larger contact surface between hosel  14  and hosel  16  is available to be epoxied together to withstand the impact force between club and golf balls. 
         [0089]    To minimize the possibility of vibration caused by ball-club impacts, a damper or a pre-load spring can be added, for example between the shaft and the club head or portion thereof as shown in  FIG. 20D .  FIG. 20D  is an enlarged portion  FIG. 20C , showing damper/spring  240 . It is noted that damper/spring  240  can be used with any of the embodiments discussed and claimed herein. Part  240  can be an elastomeric or viscoelastic member designed to absorb vibration caused by impacts, and can be compressed between the hosel and the club head, as shown. Alternatively, part  240  can be one or more spring washers being compressed between the hosel and the club head to absorb the vibration. Suitable spring washers include, but are not limited to, Belleville or cupped spring washers, star spring washers, wave spring washers, curve spring washers, and locking washers. 
         [0090]    Also, any of the threaded connections described herein, can be reinforced by a threaded helical coil, commercially available as Helicoil™ from many sources, including Emhart Teknologies. These coils are precision formed screw thread coils made from stainless steel, titanium or other durable metals, that have a diamond shaped cross-section. These coils are inserted into threaded holes, and are adapted to receive threaded fasteners. These coils are designed to be placed snugly between the threaded fasteners and threaded holes, and are designed to spread the load evenly among the threads. Typically, these coils are harder than the holes and the fasteners to minimize the possibility of thread tripping. 
         [0091]    Typically, shafts  14  are long and slender and their geometry affects the number of teeth that can be present on serrated surfaces  17  and  19 , as shown generally in  FIGS. 1-2 , as well as the geometry of these teeth. The size of the teeth also needs to be sufficiently robust to withstand the stresses and torque applied to the shaft. The cutting tools have their own limitation as to how small they can cut the serrated teeth. The inventors of the present invention have discovered that in one preferred embodiment three teeth on each hosel insert  16 ,  18  can sufficiently perform the anti-rotation function, as shown in  FIGS. 19A-C . As shown, hosel part  16  has three thick tapered teeth  230  and hosel part  18  has three corresponding thin tapered teeth  232 . Alternatively, thick tapered teeth  230  can be associated with hosel part  18  and vice versa. The slopes of tapered teeth  230  and tapered teeth  232  are substantially the same and are from about 20° to about 40°, preferably from about 25° to about 35°, and more preferably about 30°. Such angle extends the wear of the teeth and allows debris and dirt to escape. Teeth  232  can be from about 0.07 inch to 0.25 inch in height, preferably between about 0.09 inch to about 0.20 inch in height, and more preferably between about 0.10 inch to about 0.15 inch in height. 
         [0092]    In accordance with another aspect of the present invention, the tapered teeth (or prongs) on serrated surfaces  17  and  19 , such as teeth  230  and  232 , do not come into contact with the opposing hosel part, so that the tapered teeth or prongs don&#39;t bottom out or come into contact with the opposing hosel part. In other words, a gap  236  shown in  FIG. 19A  is present when hosel parts  16  and  18  are assembled. This provides a manufacturing tolerance so that hosel parts  16  and  18  can fit flush together. For example, if no gap  236  is allowed and one of the teeth is slightly longer than the rest, then when assembled this longer tooth prevents the two hosel parts from coming flush together.  FIG. 19D  illustrates another example of gap  236  with tapered teeth  230  and  232  having substantially the same size. 
         [0093]    Alternative joining systems may be used to reversibly attach and detach club heads from shafts. These systems can be used for club sets having interchangeable heads as well as clubs having adjustable loft and/or lie angles. In some embodiments, such as shown in  FIGS. 21A and 21B , a shaft  310  will interface with a club head  320  using a fastener  330  designed to be received by the end of the shaft  310 . In some embodiments, the club head  320  will comprise a heel opening  323  that allows the fastener  330  to pass through, however a head  360  of the fastener (see  FIG. 22 ) cannot pass through the heel opening. As such, the fastener  330  exerts a force between the club head  320  and the shaft  310  as the fastener  330  is tightened, e.g., with rotation. While not shown in detail in  FIGS. 21A and 21B , it is understood that rotation of the shaft  310  may be limited by the hosel  327 , which may include a serrated surface, e.g., as described above. The design allows the shaft  310  to be loosened, the shaft  310  rotated with respect to the club head  320 , and then the fastener  330  retightened in order to change the trajectory profile of the club head  320  with respect to the shaft  310 . While not shown in  FIG. 21A , the hosel  327  may have an opening, e.g., a window, that is designed to indicate a loft or lie angle corresponding to the position of the shaft  310 . 
         [0094]    While  FIGS. 21A and 21B  clearly show the fastener  330  mating with the shaft  310 , a user of the club will, in fact need to mate the fastener  330  with the shaft blindly. That is, the user will have to align the fastener  330  axially with the shaft so that the fastener can mate with the appropriate structure in the shaft  310 , e.g., a threaded hole, in order to secure the shaft  310  without damaging the fastening mechanism, e.g., cross-threading a screw. Optimally, the fastener  330  will also be held in an elevated position even when the club is normally-oriented (i.e., the fastener  330  is upside down), thereby making it easier to mate the shaft  310 , e.g., by initially hand-threading the shaft  310  onto the fastener  330 . 
         [0095]    These goals are met with the design shown in  FIG. 21B  whereby a fastener  330  having a retaining shoulder  340  is held in place by a retaining structure  350 . With the design shown in  FIG. 21B , the fastener  330  cannot move down away from the heel opening  323  nor can it move substantially from the axis of the shaft  310 . The fastener  330  can rotate freely, however, making it easier to engage the shaft  310 . Additionally, because the retaining structure  350  does not interact with the fastener  330  except to hold it in place, the retaining structure  350  will not be damaged with repeated attachment of the club head  320  to the shaft  310 . That is, if the retaining structure  350  interacted with a threaded portion of fastener  330 , it is possible that the retaining structure could be stripped or pulled away from the heel opening  323  with repeated engagement of the fastener  330 . 
         [0096]    When used to attach a golf club head to a golf club shaft, the inventive design in  FIG. 21B  benefits the golfer by making the club head lighter and easier to manufacture, thus reducing costs. Prior art designs used align a fastener similar to fastener  330  have required intricate extensions to be cast or stamped into the head  320  to maintain the fastener alignment. Such extensions make the head more difficult to manufacture, and result in added weight. 
         [0097]    Using the design of  FIG. 21B , for example, the heel opening  323  can be closer to the bottom of the head, reducing the complexity of placing the heel opening  323 . Additionally, the material surrounding the heel opening  323  can be fabricated from thinner materials, further reducing cost and weight. Furthermore, the weight that is required to secure the retaining structure  350  is moved lower in the head  320 . In the embodiment shown in  FIG. 21B , it is estimated that the use of the disclosed retaining structure  350  saves between 1 and 2 grams of weight. 
         [0098]    An embodiment of a fastener  330  having a retaining shoulder is shown in  FIG. 22 . The fastener  330  also has a head  360  and a threaded portion  370 . The head  360  has an engagement structure  365  ( FIG. 23 ) configured to receive a tool, such as an Allen key or a screwdriver. The tool need not have a particular configuration, as any configuration, such as triangular, square, pentagonal, hexagonal, heptagonal, octagonal, cross, slot, or star shaped, can be used to secure fastener  330  to shaft  310 . The retaining shoulder  340  is shown as a tapered ring that fits on fastener  330  and interacts with retaining structure  350  to keep fastener  330  in the desired position. The retaining shoulder  340  need not be tapered, as it can be semicircular, triangular, or rectangular in cross-section provided that it can interact with the retaining structure  350  to keep the fastener  330  in position. Alternatively, retaining shoulder  340  can be a slotted ring or a clip provided that the retaining shoulder can move through the retaining structure  350 . If the retaining shoulder  340  is a separate piece that mates with the fastener  330 , it may be constructed from metal or plastic. In alternative embodiments, the retaining shoulder  340  can be integral with the fastener, e.g., a bolt having a shaft with a slot cut in it toward the threaded end to interact with the retaining structure  350 . While the fastener is depicted as a screw or a bolt, fastener  330  may alternatively be a hook structure, or a shaft with a structure to interact with a slot, similar to the structure described in  FIGS. 8 and 9 . Fastener  330  may be fabricated from metal, such as steel, aluminum, or titanium, or from a resilient plastic or lightweight composite. 
         [0099]      FIG. 23  shows a cross-section detailing the interaction between retaining structure  350  and fastener  330 . Retaining structure  350  is typically a thin structure protruding from the interior surface of the club head in an upward direction toward the shaft  310 , as shown in  FIG. 21B . The protrusions of retaining structure  350  must be sufficiently resilient to accept the retaining shoulder  340  of the fastener  330  and then return to a position to restrain the fastener  330  via the retaining shoulder  340  as shown in  FIG. 23 . In some embodiments, as shown in  FIG. 23 , the head  360  of fastener  330  will provide pressure against the club head directly. In other embodiments, the head may provide pressure against a washer or another intermediate structure which provides pressure against the head  320 . 
         [0100]    The retaining structure  350  may be integrated into the club head, or an independent retaining member may be used to secure the fastener  330  in the correct position. In embodiments wherein the retaining structure  350  is integrated into the club head, the retaining structure  350  will typically be constructed from the material of the club head, e.g., aluminum, titanium, or composite. In other embodiments, a retaining member, such as depicted in FIGS.  24 A,B and  25 A,B, is the retaining structure  350  that holds fastener  330  in the desired position. 
         [0101]    As shown in  FIG. 24A , a retaining member may comprise a sleeve  400  of lightweight material, having slots to allow the protrusions to expand to receive the retaining shoulder  340  and then return to a shape to hold the retaining shoulder  340  in place. Once fastener  330  is secured in sleeve  400 , the sleeve and fastener  330  can be inserted into the heel opening  323  in the heel of the club. The annular protrusions  410  on the sleeve  400  will cause the sleeve  400  to be secure in the heel opening  323 , thereby keeping fastener  330  at the correct height and axially-aligned with the shaft  310 . The sleeve  400  additionally assures that fastener  330  does not fall from the club head when not engaged with the shaft  310 . The sleeve  400  can be made from any suitable lightweight and resilient material such as plastic, composite, or metal. In preferred embodiments, the sleeve  400  is constructed from injection molded plastic. A cross section of the fastener  330  mated with the sleeve  400  is shown in  FIG. 24B . 
         [0102]    Other retaining member structures can be used to retain fastener  330  with club head  320 , as shown in  FIGS. 25A and 25B .  FIG. 25A  shows a clip  500  suitable to retain fastener  330  via retaining shoulders  340 . In  FIG. 25A , the clip  500  is shown in a relaxed state, i.e., not interfaced with a fastener  330 . The clip  500  has a plurality of protrusions that allow the clip to expand to receive the retaining shoulder  340  of fastener  330  and then return to a position suitable to restrict motion of retaining shoulder  340  (See  FIG. 25B ). Like the sleeve  400  shown in  FIGS. 24A and 24B , the clip  500  is inserted into the heel opening  323  once assembled. A waist  510  causes the clip  500  to be retained, as shown in  FIG. 25B . Other suitable clips  500  may be designed to meet the same needs with similar structures. The clip  500  can be made from any suitable lightweight and resilient material such as plastic, composite, or metal. In preferred embodiments, the clip  500  is constructed from injection molded plastic. A cross section of the fastener  330  mated with the clip  500  is shown in  FIG. 25B . 
         [0103]    The embodiments of the present invention are illustrated with driver-type or iron-type clubs. However, it is understood that any type of golf club, e.g., hybrid, wedge, or putter, can use one or more of the connection systems  10  disclosed. Additionally, connection system  10  can be used with non-golf equipment, such as fishing poles, tennis rackets, squash rackets, racquetball rackets, lacrosse sticks, aiming sights for firearms, hammers, axes, plumbing, etc. 
         [0104]    While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Elements from one embodiment can be incorporated into other embodiments. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention. 
       INCORPORATION BY REFERENCE 
       [0105]    References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, and web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes. 
       EQUIVALENTS 
       [0106]    Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.