Device and method for adjusting the total weight and/or the swingweight of a golf club shaft

Abstract

An annular or porous insert of predetermined weight is mounted at a predetermined location within a tubular golf shaft, the shaft being of any suitable material including either metal or graphite. The insert is circumferentially uniform and is dimensioned so that it does not of itself have an impact on the swing characteristics of the shaft, other than the swingweight and/or the total weight of the manufactured shaft. In this way the swingweight and/or the total weight of the shaft can be altered without having to change the construction of the shaft. Furthermore the insert is simple to install at any desired location and it does not interfere with the assembly of the finish club, nor does it violate the standards of the USGA.

What is claimed is:  
     
         1 . A golf club shaft comprising: 
 an elongated tube extending from a larger diameter buft end to a smaller diameter tip end;    said tube having a total weight distributed over the length of said tube, said length and said distribution of said total weight together yielding a determinable swingweight characteristic of said tube; and    a circumferentially uniform insert mounted in said tube, said insert comprising a cylinder having an overall average weight per unit length of approximately 4 gm/inch or more, said cylinder having an opening therethrough to permit air to pass from one end of said cylinder to the other.    
     
     
         2 . A golf club shaft as claimed in    claim 1    wherein said insert has a predetermined weight and a predetermined position in said tube, said insert weight and said position being selected to modify at least one of the total weight of said shaft and the swingweight of said shaft from the corresponding value of said tube.  
     
     
         3 . A golf club shaft as claimed in    claim 2    wherein said insert is positioned above a selected fulcrum in said tube to reduce the swingweight of said shaft compared to the swingweight of said tube.  
     
     
         4 . A golf club shaft as claimed in    claim 1    wherein said insert comprises a radially compressible material having a uncompressed outer diameter greater than the internal diameter of said tube at the mounting point of said insert.  
     
     
         5 . A golf club shaft as claimed in    claim 1    wherein the length of said insert is less than 10% of the length of said tube.  
     
     
         6 . A golf club shaft comprising: 
 an elongated tube extending from a larger diameter butt end to a smaller diameter tip end;    said tube having a fixed weight distribution over the length of said tube, said length and said weight distribution together yielding a determinable swingweight characteristic of said tube; and    a circumferentially uniform insert mounted in said tube, said insert being located within the butt region of said shaft and being sufficiently heavy to reduce the swingweight of said shaft below said swingweight of said tube.    
     
     
         7 . A golf club shaft as claimed in    claim 6    wherein the length of said insert is less than 10% of the length of said tube.  
     
     
         8 . A golf club shaft comprising: 
 an elongated tube extending from a larger diameter butt end to a smaller diameter tip end;    said tube having a fixed weight distribution over the length of said tube, said length and said weight distribution together yielding a determinable swingweight characteristic of said tube; and    a tubular insert fixedly mounted in said tube, said insert having an overall average weight per unit length of approximately 4 gm/inch or more, and having a central bore therethrough to permit air to pass from one end of said cylinder to the other;    said insert further comprising a radially compressible material having a uncompressed outer diameter greater than the internal diameter of said tube at the mounting point of said insert;    the length of said insert being less than 10% of the length of said tube.    
     
     
         9 . A golf club shaft as claimed in    claim 8    wherein said insert has a total weight and a position in said tube selected to modify the swingweight of said shaft by a predetermined amount.  
     
     
         10 . A method for adjusting the swingweight of a golf club shaft comprising the steps of: 
 manufacturing a shaft tube having a larger diameter butt end and a smaller diameter tip end;    determining the swingweight of said tube;    mounting a cylindrical insert of predetermined weight within said tube at a predetermined distance from a selected fulcrum of said tube, said weight and said location being sufficient to change the swingweight of said tube by a selected amount.    
     
     
         11 . A method for adjusting the swingweight of a golf club shaft comprising the steps of: 
 manufacturing a shaft tube having a larger diameter butt end and a smaller diameter tip end;    determining the swingweight of said tube by a method which includes the identification of a fulcrum along the length of said tube;    preparing a cylindrical insert having an overall average weight per unit length in excess of about 4 grams per inch, the length of said insert being less than 10% of the length of said shaft tube and having an opening therethrough to permit the passage of air; and    mounting said insert within said shaft tube at a predetermined distance from said fulcrum to alter the swingweight of said tube by a selected amount.    
     
     
         12 . A method as claimed in    claim 11    wherein said insert comprises a radially compressible material having an uncompressed outer diameter greater than the internal diameter of said shaft tube at the mounting point of said insert.  
     
     
         13 . A method as claimed in    claim 12    wherein said insert comprises an adhesive and said method comprises the further step of curing said adhesive to fix said insert at said mounting location.  
     
     
         14 . A method as claimed in    claim 13    wherein said insert comprises a tube having a central bore there through, said tube being circumferentially uniform at any radial distance from its center.  
     
     
         15 . A device for adjusting the swingweight of a golf club shaft, said device comprising: 
 a cylindrical insert having an overall average weight per unit length of approximately 4 gm/inch or more;    said insert including an open passage therethrough to permit air to pass from one end of said insert through to the other; and    said insert including a curable adhesive for mounting said insert at a selected location in a golf club shaft.    
     
     
         16 . A device as claimed in    claim 15    wherein the mechanical properties of said device are circumferentially uniform at any radial distance from its center.  
     
     
         17 . A device as claimed in    claim 15    wherein the length of said insert is sufficient to affect the swingweight of a golf club shaft by a desired amount without affecting the stiffness and torsional rigidity of the shaft.  
     
     
         18 . A device as claimed in    claim 15    wherein said insert comprises an open cell foam which permits the passage of air therethrough from one end to another.  
     
     
         19 . A device as claimed in    claim 15    wherein said insert comprises a tube having a central bore therethrough.  
     
     
         20 . A device as claimed in    claim 19    wherein said tube comprises a resiliently compressible material.  
     
     
         21 . A device as claimed in    claim 20    wherein said tube comprises polyisobutylene.  
     
     
         22 . A device for adjusting the swingweight of a golf club shaft, said device comprising: 
 a tubular insert having a central bore extending therethrough, said insert having an overall average weight per unit length of approximately 4 gram per inch or more;    said insert being resiliently compressible in a radial direction;    said insert having mechanical properties which are circumferentially uniform at any radial distance from the center thereof; and    a sufficient quantity of curable adhesive for mounting said insert at a selected location in a golf club shaft.    
     
     
         23 . A device for adjusting the swingweight of a golf club shaft, said device comprising: 
 a cylindrical insert having an overall average weight per unit length of approximately 4 gm/inch or more;    said insert including an open passage therethrough to permit air to pass from one end of said insert through to the other;    said insert being resiliently compressible in a radial direction for temporary retention thereof at a specified location in a golf club shaft; and    said insert including an adhesive, said adhesive being curable to mount said insert at said location in the golf club shaft.    
     
     
         24 . A device as claimed in    claim 23    wherein said insert comprises a tube, said tube having a centrally located bore extending through the length of said insert.  
     
     
         25 . A device as claimed in    claim 24    wherein the distribution of material in said tube is circumferentially uniform at any radial distance from its center to provide circumferentially uniform mechanical properties.