Abstract:
A variable length shaft assembly comprising at least one upper shaft portion, a lower shaft portion and a threaded fastener, wherein the threaded fastener removably connects the upper shaft portion to the lower shaft portion, is disclosed herein. The variable length shaft assembly may further comprise at least two upper shaft portions having different lengths so a golfer can adjust the total length of the shaft by removing one upper shaft portion and replacing it with another upper shaft portion having a different length. Methods of adjusting the length of a golf club shaft without damaging any portion of the shaft and variable length shaft kits are also disclosed herein.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application is a division of U.S. patent application Ser. No. 13/038,254 filed on Mar. 1, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 13/008,806, filed on Jan. 18, 2011, which claims priority to U.S. Provisional Patent Application No. 61/422,982, filed on Dec. 14, 2010. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a variable length shaft assembly that allows for quick, semi-permanent length adjustments. More specifically, the present invention relates to a variable length shaft whose length can be adjusted in a short period of time with the use of shaft extension components having different lengths. 
     2. Description of the Related Art 
     Customization of golf clubs to help golfers attain better shots has become a popular and more prevalent practice in recent years. Golf club manufacturers and designers have devised various features to allow club fitters and golf club players to adjust certain characteristics of their clubs. Such characteristics include loft, lie, face angle, center of gravity (CG) location, and club length. 
     Current technology provides two methods to adjust overall club length. One such method involves the destruction and removal of the grip on a shaft. Upon removal of the grip by peeling or tearing, the end portion of the shaft is trimmed to decrease the club length or an extension piece is affixed to the end of the shaft to increase its length. Aftermarket extensions are available specifically for this purpose; alternatively, extensions can be made from portions of other golf club shafts that are cut to the desired length and then inserted into the end of the first club&#39;s shaft. The extension piece must match the diameter of the existing shaft, so it is necessary at times to build up the diameter of the extension or existing shaft by adding layers of tape. This method requires that the user making the adjustments have access to potentially expensive new components and toots as well as having a high level of skill. It also causes damage to the original shaft and grip. 
     The second method of adjusting club length involves replacing the entire shaft and grip using a semi-permanent head-shaft connection device that some manufacturers offer with their clubs, particularly with drivers. The existing shaft may be removed from the driver head and replaced with a different shaft that has either a shorter or longer length. This method is not possible on all clubs, however, as the head must have hardware that allows for removal of the shaft and replacement with anew shaft without damaging the head. 
     A golfer who does not possess club altering skills or the necessary disposable income to purchase new components likely will be daunted by these two methods of adjusting club length. The first method requires the golfer to make use of several tools to remove the grip and cut the shaft if he or she desires a shorter length, and also to have materials such as tape and a replacement grip on hand to replace the grip and mend any damage caused to the shaft and grip. The skill set required to change the shaft length using this method is usually beyond the abilities of the average golfer, so the golfer would need to seek the services of a golf club fitter or technician to have their club length changed. The second method requires the golfer to buy an entirely new shaft at a different length, which can be very expensive, and also may require the golfer to retain a golf club titter or technician to replace the shaft. 
     Ultimately, the two methods described above require an inventory of spare components and above average technical skill, particularly with regard to the first method. It is therefore desirable to facilitate the change of a club&#39;s length using a faster, easier, and less expensive system and method than is currently available. 
     BRIEF SUMMARY OF THE INVENTION 
     One aspect of the present invention is a variable length golf club shaft comprising at least one upper shaft portion, a lower shaft portion, and a threaded fastener, wherein the threaded fastener removably connects the upper shaft portion to the lower shaft portion. The upper shaft portion may further comprise an upper shaft piece and an upper grip piece, and the lower shaft portion may further comprise a lower shaft piece and a lower grip piece. The upper shaft piece and the lower shaft piece may be composed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy, steel, magnesium, magnesium alloy, plastic, and graphite composite, and in a further embodiment the upper and lower shaft pieces may be composed of graphite composite. 
     In a further embodiment, the variable length golf club shaft further comprises an upper adapter having a hole through its center and a lower adapter having a threaded hole through its center, wherein the upper adapter is affixed to a lower, interior surface of the upper shaft portion, wherein the lower adapter is affixed to an upper, interior surface of the lower shaft portion, and wherein the threaded fastener is insertable through the holes in the center of the upper and lower adapters. The head portion of the threaded fastener may be permanently enclosed by a screw captivator affixed to the upper adapter. The upper and lower adapters of the variable length golf club shaft may be composed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy, steel, magnesium, magnesium alloy, plastic, and graphite composite. 
     The variable length golf club shaft may further comprise an upper o-ring disposed proximate the upper adapter and a lower o-ring disposed proximate the lower adapter. The variable length golf club shaft may also further comprise at least two upper shaft portions, wherein the at least two upper shaft portions have different lengths. The at least two upper shaft portions may differ in length from each other by no less than 0.5 inch, and they may differ in weight from each other or have the same weight. 
     Another aspect of the present invention is a method of adjusting the length of a golf club shaft comprising providing an assembled golf club shaft having a first removable upper portion with a first threaded fastener and a lower portion, loosening the first threaded fastener engaging a tower surface of the first removable upper portion to an upper surface of the lower portion, removing the first removable upper portion from the lower portion, aligning a lower surface of a second removable upper portion having a second threaded fastener with the upper surface of the lower portion, and tightening the second threaded fastener such that the second upper removable portion is semi-permanently affixed to the lower portion, wherein the first removable upper portion has a length that differs from the length of the second removable upper portion. 
     Yet another aspect of the present invention is a method of adjusting, the length of a golf club shaft comprising removing a first upper portion from the golf club shaft, replacing the first upper portion of the golf club shaft with a second upper portion having a length that differs from that of the first upper portion, and securing the second upper portion to the golf club shaft, wherein the removing, replacing, and securing does not cause damage to any portion of the golf club shaft. 
     Another aspect of the present invention is a kit comprising at least two upper shaft portions, a lower shaft portion, a threaded fastener, and a tool, wherein the at least two upper shaft portions have different lengths, wherein the tool engages the threaded fastener to tighten or loosen the threaded fastener, and wherein the threaded fastener removably connects the lower shaft portion with the at least two upper shaft portions. The at least two upper shaft portions may have different weights, or may have the same weight. 
     Yet another aspect of the present invention is a two-piece grip for a golf club shaft, the two-piece grip comprising an upper grip piece and a lower grip piece, wherein the upper grip piece has a single opening to receive an end portion of the golf club shaft, wherein the lower grip piece has an upper opening and a lower opening connected by a bore to receive an upper portion of the golf club shaft, and wherein the upper grip piece single opening is located proximate the lower grip piece upper opening when the two-piece grip is assembled on the golf club shaft. The upper grip piece and the lower grip piece may be molded from a rubber compound. 
     In one further embodiment, the upper grip piece comprises a first collar proximate the single opening and the lower grip piece comprises a second collar proximate the upper opening. The first collar may contact the second collar when the two-piece grip is assembled on the golf club shaft. The first collar may also comprise at least one slit. The first collar may contact the second collar at a ninety degree angle or a non-ninety degree angle with respect to a vertical shaft axis. 
     In another further embodiment, the upper grip piece comprises a first set of serrations proximate the single opening, the lower grip piece comprises a second set of serrations proximate the upper opening, and wherein the first and second sets of serrations interlock when the two-piece grip is assembled on the golf club shaft. 
     In yet another further embodiment, the upper grip piece may comprise a set of protrusions proximate the single opening and the tower grip piece may comprise a set of depressions proximate the upper opening, wherein the protrusions and the depressions interlock when the two-piece grip is assembled on the golf club shaft. Alternatively, the upper grip piece may comprise a set of depressions proximate the single opening and the lower grip piece may comprise a set of protrusions proximate the upper opening, wherein the protrusions and the depressions interlock when the two-piece grip is assembled on golf club shaft. 
     In another further embodiment, the upper grip piece contacts the lower grip piece at a ninety degree angle or a non-ninety degree angle with respect to a vertical shaft axis when the two-piece grip is asset bled on the golf club shaft. 
     Yet another aspect of the present invention is a variable length golf club shaft comprising at least one upper shaft portion, a lower shaft portion, and a threaded fastener, wherein the threaded fastener removably connects the upper shaft portion to the lower shaft portion, wherein the at least one upper shaft portion comprises an upper shaft piece and an upper grip piece, wherein the lower shaft portion comprises a lower shaft piece and a lower grip piece, and wherein the upper grip piece contacts the lower grip piece when the at least one upper shaft portion and the lower shaft portion are connected. The upper grip piece and the lower grip piece may each be composed of a rubber compound. The upper grip piece and the lower grip piece may contact each other at ninety degree or non-ninety degree angles with respect to a vertical shaft axis. The upper grip piece may further comprise a first set of serrations and the lower grip piece may further comprise a second set of serrations, wherein the first and second sets of serrations interlock when the upper grip piece contacts the lower grip piece. 
     In a further embodiment, the variable length golf club shaft also comprises an upper adapter having a hole through its center and a lower adapter having a threaded hole through its center, wherein the upper adapter is affixed to a lower, interior surface of the upper shaft portion, wherein the lower adapter is affixed to an upper, interior surface of the lower shaft portion, and wherein the threaded fastener is insertable through the holes in the center of the upper and lower adapters. The upper grip piece may further comprise a first collar and the lower grip piece may further comprise a second collar, and each of these collars may contact the upper and lower adapters, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an exploded side view of the variable length shaft of the present invention. 
         FIG. 2  is a top plan view of the variable length shaft of the present invention. 
         FIG. 3  is aside cross-sectional view of the variable length shaft shown in  FIG. 2  along lines A-A. 
         FIG. 4  is a close-up image of the circled section of the variable length shaft shown in  FIG. 3 . 
         FIG. 5A  is a side cross-sectional view of another embodiment of a variable length shaft connection region. 
         FIG. 5B  is a side perspective view of an assortment of upper grip pieces having different collar configurations. 
         FIG. 6A  is a side cross-sectional view of upper and lower grip pieces having an assortment of interlocking mating interfaces. 
         FIG. 6B  is a side cross-sectional view of upper and lower grip pieces having a non-ninety degree angle mating interface. 
         FIGS. 7A and 7B  are side views of a tool interacting with an unassembled variable length shaft of the present invention. 
         FIGS. 8A and 8B  are side views of a tool interacting with an assembled variable length shaft of the present invention. 
         FIG. 9  is a side view of different lengths of upper shaft sections of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a variable length shaft that provides club length adjustability. Club length adjustability is an advantageous feature for golf clubs because, for example, extending the length of a club can have the desired effect of increasing club head speed, which results in longer driving distances. Conversely, shortening the length of a club would provide a golfer with more control and accuracy in driving the golf ball. Golf course conditions often require accurate driving due to hazards, including but not limited to water, rough, and out of bounds markers, and driving accuracy can be more preferred than driving distance in competitive situations. 
     The present invention is also valuable because a golfer&#39;s swing may change over time, thus requiring alterations to his or her clubs. A golfer may improve his or her game through lessons and may gain greater flexibility and strength through practice and exercise. As such, it is reasonable for a golfer to wish to change his or her club&#39;s length to help improve his or her accuracy, distance, and feel as needed or desired. 
     The present invention provides golfers with a system and method to easily, quickly and inexpensively modify the length of their golf clubs to have them perform in a desired manner. This invention will enable golfers to change their club length wherever they wish, including, but not limited to, at the practice range, the golf course, and their home. The present invention also is designed to avoid altering a club&#39;s swing weight or its “feel.” The tool and components that are used to alter a club&#39;s length are small and can be carried in a pocket of the user&#39;s golf bag. Furthermore, the technical ability required to modify the golf club length according to this invention is minimal and its approach is intuitive and easy for a golfer to understand. 
     A preferred embodiment of the present variable length shaft invention is shown in  FIGS. 1-4 . According to the preferred embodiment of the invention, and as shown in  FIGS. 1 and 4 , two sections of the shaft  10 , the lower shaft and grip section  20  and the upper shaft and grip section  30 , are joined together proximate the upper end  25  and lower end  35  of the shaft portions  24 ,  34 , respectively, along a demarcation line  200 , the line at which the two sections  20 ,  30  meet. 
     As shown in  FIGS. 3 , and  4 , the lower shaft and grip section  20  includes a lower grip portion  22  that encircles and is affixed to a lower part of the shaft  24  with double-sided adhesive tape (not shown). In other embodiments, the lower grip portion  22  may be affixed to the shaft  24  with another type of adhesive material. A lower adapter  40  is affixed to or otherwise situated proximate the upper, interior surface of the lower part of the shaft  24 , and a lower-adapter o-ring  80  may be used to seal or otherwise secure the connection between the lower adapter  40  and the interior surface of the lower part of the shaft  24 , as shown in  FIG. 4 . The lower adapter  40  also contacts an interior surface of the lower grip portion  22  in the preferred embodiment of the present invention, also as shown in  FIG. 4 . This adapter  40  includes a threaded hole  45  in its center to receive a screw  50  that allows the adapter  40  to be fastened to the upper shaft and grip section  30 . 
     The upper shaft and grip section  30  correspondingly as an upper grip portion  32  encircling and affixed to an upper shaft portion  34  with double-sided adhesive tape (not shown), or, in other embodiments, another kind of adhesive material. The upper shaft and grip section  30  has an upper adapter  60  affixed to or otherwise situated proximate the lower, interior surface of the upper shaft portion  34 , and an upper-adapter o-ring  90  may be used to seal the connection between the upper adapter  60  and the upper shaft portion  34 . The upper adapter  60  also contacts an interior surface of the upper grip portion  32  in the preferred embodiment of the present invention, which is also shown in  FIG. 4 . The upper adapter  60  has a hole  65 , which in the preferred embodiment is not threaded, in its center to receive the screw  50  that mates with the lower adapter  40  associated with the lower shaft and grip section  20 , and is affixed to a screw captivator  70  that prevents the screw  50  from falling out of or otherwise becoming dislodged from the upper adapter  60 . In another embodiment, the hole  65  can be threaded. 
     As shown in  FIGS. 1 and 4 , assembly of the preferred embodiment of the invention requires that the lower shaft and grip section  20  and the upper shaft and grip section  30  be aligned and pressed together in their proper orientation at a demarcation line  200 , the line where the two parts connect. The screw  50  located in the upper adapter  60  is threaded into the threaded hole  45  of the lower adapter  40  and tightened with a specifically provided tool  100 , as shown in  FIGS. 7A ,  7 B,  8 A, and  8 B. The adapters  40 ,  60  may further include anti-rotational features to restrict twisting along the shaft axis when they are screwed together. When the screw  50  has been secured, the two shaft and grip sections  20 ,  30  are interlocked securely together, thus allowing the club to be used to hit golf balls. This operation allows for a semi-permanent assembly that will make the golf club comply with the appropriate USGA rules of golf. 
     In a further embodiment, shown in  FIGS. 5A and 5B , the upper grip portion  32  and the lower grip portion  22  include a lip or collar  33 ,  23 . The upper grip portion  32  collar  33  is located at a single opening of the upper grip portion  32 , and the lower grip portion  22  collar  23  is located at an upper opening in the lower grip portion  22 . When the upper grip portion  32  contacts the lower grip portion  22  with their respective adapters  60 ,  40  installed, as shown in  FIG. 5A , the collars  33 ,  23  ensure a good fit between the upper and lower grip portions  32 ,  22  and consistent grip length during the gripping operation. The collars  33 ,  23  also help retain the adapters  60 ,  40  within the upper and lower grip portions  32 ,  22 . By interfacing at a plane  17  normal to the shaft  10  axis  15 , as shown in  FIG. 5A , the collars  33 ,  23  provide greater contact between the upper and lower grip portions  32 ,  22 , than in upper and lower grip portions that do not include collars  33 ,  23 . 
     In the embodiment shown in  FIG. 5B , the collar  33  of the upper grip portion  32  preferably includes one or more slits  33   a - 33   d . These slits  33   a - 33   d  can expedite production of upper grip portions  32  having different lengths, as the inclusion of a collar  33  may make it difficult to remove a core bar used to mold the inner diameter of the upper grip portions  32 . The slits  33   a - 33   d  thus allow for easier removal of the core bar from the upper grip portions  32  after molding is complete. The slits  33   a - 33   d  also make it easier to insert the upper shaft portion  34  and the upper adapter  60  into the upper grip portion  32 . 
     The contact between upper and lower grip portions  32 ,  22  can be increased by designing an interface  36  between the upper and lower grip portions to have an interlocking design, such as one of the designs shown in  FIG. 6A . The interlocking design may include serrations or may include protrusions in one grip portion  32 ,  22  that fit within depressions in the other grip portion  32 ,  22 , as shown in  FIG. 6A . The interlocking features between the upper and lower grip portions  32 ,  22  may also be used as a decorative styling and may be present on the upper and lower grip portions  32 ,  22  when a collar  33 ,  23  is present or absent. An alternative way to increase contact between the grip portions  32 ,  22 , as shown in  FIG. 6B , is to design the upper and tower grip portions to contact each with other at an interface  36  along a plane  17  having anon-ninety degree angle with respect to the shaft axis  15 . 
       FIGS. 7A ,  7 B,  8 A, and  8 B show a tool  100 , having an extension portion  105  and a head portion  110 , which can be used to assemble the upper and lower shaft and grip sections  20 ,  30 . As shown in  FIG. 7A , and with reference to  FIG. 4 , the extension portion  105  of the tool fits through a hole  38  at the topmost portion of the upper grip portion  32 , extends through the upper shaft portion  34 , the screw captivator  70 , and the upper adapter  60 , and contacts the screw  50 . The screw captivator  70  specifically guides the extension portion  105  to contact the screw  50 . As shown in  FIG. 8A , once the extension portion  105  of the tool  100  engages the head of the screw  50 , the tool head portion  110  can be twisted clockwise or counterclockwise to tighten or loosen, respectively, the screw  50  and therefore the connection between the upper and lower shaft and grip sections  20 ,  30 . 
     In the preferred embodiment of the present invention, the length of the lower shaft and grip section  20  is not altered, as shown in  FIG. 9 . In other words, a golfer would not exchange the tower shaft and grip section  20  for a lower shaft and grip section  20  of a different length. The lower shaft and grip section  20  of the present invention thus can be permanently affixed to a desired golf club head (not shown). In contrast, according to the preferred embodiment of the present invention and as disclosed in  FIG. 9 , the upper shaft and grip section  30  of a normal length club  355  can be easily swapped for other upper shaft and grip sections  305 ,  310 ,  315 ,  320 ,  325 ,  330 ,  335 ,  340 ,  345 ,  350  having different lengths. The upper shaft and grip sections  305 ,  310 ,  315 ,  320 ,  325 ,  330 ,  335 ,  340 ,  345 ,  350  may also have different weights to allow the golfer to change the club weight as desired. Alternatively, the upper shaft and grip sections  305 ,  310 ,  315 ,  320 ,  325 ,  330 ,  335 ,  340 ,  345 ,  350  may all have the same weight. 
       FIG. 9  discloses an assortment of upper shaft and grip sections  30 , each having different lengths such that the total club length can range from a short, 43-inch club  360  to a long, 48-inch club  370 . The assortment of upper shaft and grip sections  30 ,  305 ,  310 ,  315 ,  320 ,  325 ,  330 ,  335 ,  340 ,  345 ,  350 , shown in  FIG. 9  may all be sold to a golfer with the lower shaft and grip section  20  in a kit form, or a smaller selection of such upper shaft and grip sections  30  may be included in a kit. As such, if a golfer wishes to increase the length of a shaft, he or she may remove the upper shaft and grip section  30  using the tool  100  and replace it with an upper shaft and grip section  30  having a greater length  335 ,  340 ,  345 ,  350 . In contrast, if the golfer wishes to decrease the length of the shaft, he or she may remove the upper shaft and grip section  30  using the tool  100  and replace it with an upper shaft and grip section having a shorter length  305 ,  310 ,  315 ,  320 ,  325 ,  330 . This invention thus allows the golfer to increase or decrease the length of a golf club shaft without detaching the lower shaft and grip section  20  from the club head or cutting or otherwise damaging any part of the shaft or grip. 
     The pieces of the variable length shaft  10  of the present invention may be composed of any number of materials, including metals, plastics, rubbers, and composites. The shaft portions  24 ,  34 , the screw  50 , the screw captivator  70 , the adapters  40 ,  60 , and the tool  100  may be composed of titanium, graphite or carbon composite, plastic, magnesium, aluminum, steel, or alloys of such materials, specifically stainless steel 17-7 or titanium 6-4. The shaft portions  24 ,  34  preferably are composed of graphite. The grip portions  22 ,  32  and the o-rings  80 ,  90  preferably are composed of a rubber material. The screw  50 , the adapters  40 ,  60 , and the screw captivator  70  preferably are composed of a metal material. The pieces of the variable length shaft disclosed herein may also be bonded together with an adhesive to prevent unwanted separation and ensure adequate strength during club use. 
     In a second embodiment of the invention, the variable length shaft  10  does not include grip pieces  22 ,  32 . In this second embodiment, the shaft  10  length is adjusted exactly as described herein, hut without grip pieces  22 ,  32 —instead, a grip that is appropriately sized to the shaft  10  is added once the shaft  10  is completely assembled and has desired length. The grip is preferably affixed to the shaft  10  with double sided tape, but may also be affixed with another type of adhesive material. 
     From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.