Method and apparatus for improving dynamic response of golf club

Abstract

An apparatus and method for improving the dynamic response of a golf club is disclosed. One embodiment is a shaft extension comprising a cylindrical member having a lower sleeve portion and an upper housing portion. The sleeve is sized to be inserted into the grip end of a golf club shaft with the upper housing extending from the end of the shaft. The housing has a hollow, open chamber in which a weighted insert is inserted and removably secured. Interchangeable inserts with varying masses are provided such that the dynamic response of the club may be tuned by adjusting the location of grip-end node of the fundamental modeshape of the club's response to a predetermined input.

I claim:  
     
         1 . A shaft extension for improving the dynamic response of a golf club having an elongated shaft with a lower head end and an upper grip end, the head end having a club head attached thereto and the grip end being hollow and having an inner and outer diameter, said shaft extension comprising: 
 a cylindrical member comprising a lower sleeve sized for snug insertion in said grip end of said shaft and an upper housing of a diameter slightly larger than the inner diameter of said grip end, whereby said housing extends from said shaft when said sleeve is inserted therein, said housing having a chamber therein open at the upper end thereof;    an insert of predetermined weight for insertion into said housing;    means for removably securing said insert to said housing; such that said club may be selectively weighted above the shaft for selectively improving its dynamic response without changing the overall length of the shaft and shaft extension in combination.    
     
     
         2 . The shaft extension of  claim 1  wherein said insert is one of a plurality of interchangeable and variably weighted inserts.  
     
     
         3 . The shaft extension of  claim 1  wherein said insert comprises a body for insertion into said housing and further comprises a flange at its upper end having a diameter approximately the same as the outside diameter of the housing wherein the body of said insert may be inserted into said housing until said flange abuts the upper end thereof.  
     
     
         4 . The shaft extension of  claim 3  wherein said chamber in said housing terminates at its lower end in a threaded receptacle, said one insert comprises a first longitudinal bore axially aligned with said receptacle, and said securing means comprises a retaining screw for threaded engagement with said receptacle through said first bore.  
     
     
         5 . The shaft extension of  claim 4  wherein the body of said insert is sized such that it is not in contact with the inner wall of said housing, and wherein said retaining screw has a head which is press fit into a cooperatively sized recess in the upper portion of said first longitudinal bore when said screw is threaded into said receptacle.  
     
     
         6 . The shaft extension of  claim 4  wherein said lower end of said chamber has a tapered shape of reducing diameter leading into said threaded receptacle.  
     
     
         7 . The shaft extension of  claim 6  wherein the lower end of the body of said insert is tapered complementary to said chamber.  
     
     
         8 . The shaft extension of  claim 2  wherein said insert is made principally from a material selected from the group consisting of brass, aluminum, lead, tungsten, titanium, nickel, and stainless steel.  
     
     
         9 . The shaft extension of  claim 2  wherein said sleeve is hollow.  
     
     
         10 . The shaft extension of  claim 9  wherein said cylindrical member is made principally from a material selected from the group consisting of brass, aluminum, lead, tungsten, titanium, nickel, and stainless steel.  
     
     
         11 . A shaft extension for improving the dynamic response of a golf club having an elongated shaft with a lower head end and an upper grip end, the head end having a club head attached thereto and the grip end being hollow and having an inner and outer diameter, said shaft extension comprising: 
 a cylindrical member comprising a lower sleeve of a diameter slightly smaller than the inner diameter of said grip end of said shaft for snug insertion therein and an upper housing of a diameter slightly larger than the inner diameter of said grip end of said shaft, whereby said housing extends from said shaft when said sleeve is inserted therein, said housing having an interior chamber with an opening at the top of said housing;    an insert of predetermined weight removably secured within said housing; such that said club may be selectively weighted above the shaft for selectively improving its dynamic response, without changing the overall length of the shaft and shaft extension in combination.    
     
     
         12 . The shaft extension of  claim 11 , wherein said insert is one of a plurality of interchangeable and variably weighted inserts.  
     
     
         13 . The shaft extension of  claim 11  wherein said insert comprises a body for insertion into said housing and further comprises a flange at its upper end having a diameter approximately the same as the outside diameter of the housing wherein the body of said insert may be inserted into said housing until said flange abuts the upper end thereof.  
     
     
         14 . The shaft extension of  claim 13  wherein said insert is removably secured within said chamber with a fastener.  
     
     
         15 . The shaft extension of  claim 14  wherein said chamber terminates at its lower end in a threaded receptacle, said insert has a first longitudinal bore coaxial with said threaded receptacle, and said fastener is a retaining screw, such that said retaining screw may be threaded into said receptacle through said second bore.  
     
     
         16 . The shaft extension of  claim 15  wherein the body of said insert is sized such that it is not in contact with the inner wall of said housing, and wherein said retaining screw has a head which is press fit into a cooperatively sized recess in the upper portion of said first longitudinal bore when said screw is threaded into said receptacle.  
     
     
         17 . The shaft extension of  claim 16  wherein said lower end of said chamber has a tapered shape of reducing diameter leading into said threaded receptacle.  
     
     
         18 . The shaft extension of  claim 17  wherein the lower end of the body of said insert is tapered complementary to said chamber.  
     
     
         19 . The shaft extension of  claim 12  wherein said insert is made principally from a material selected from the group consisting of brass, aluminum, lead, tungsten, titanium, nickel, and stainless steel.  
     
     
         20 . The shaft extension of  claim 12  wherein said sleeve is hollow.  
     
     
         21 . The shaft extension of  claim 20  wherein said cylindrical member is made principally from a material selected from the group consisting of brass, aluminum, lead, tungsten, titanium, nickel, and stainless steel.  
     
     
         22 . A method of improving the dynamic response of a golf club, said club having an elongated shaft with a lower head end and an upper grip end, the head end having a club head attached thereto, and wherein the golf club in response to a predetermined input exhibits a fundamental modeshape with a grip-end node at a first location, said method comprising selectively adding weight to the grip end of said club until said grip-end node moves from said first position to a second position closer to said grip end.  
     
     
         23 . The method of  claim 22  wherein said shaft has a gripping region below said grip end which is grasped by a golfer during play and wherein said weight is selectively added to said grip end of said club until the amplitude of the fundamental mode is maximized within said gripping region.  
     
     
         24 . The method of  claim 22  wherein said weight is selectively added to said club using the device of  claim 1 .  
     
     
         25 . The method of  claim 22  wherein said weight is selectively added to said club using the device of  claim 11.