Bowling ball with improved thumb support

Abstract

A bowling ball is constructed to include a thumb-engagement insert and a thumb-clearance recess positioned radially inwardly of the thumb-engagement insert.

What is claimed is: 
     
         1 . A bowling ball comprising:
 a thumb-engagement insert; and   a thumb-clearance recess positioned radially inwardly of the thumb-engagement insert.   
     
     
         2 . The bowling ball of  claim 1 :
 wherein the thumb-engagement insert has a cylindrical upper interior portion with a first diameter; and   wherein the thumb-clearance recess is cylindrical and has a second diameter larger than the first diameter.   
     
     
         3 . The bowling ball of  claim 2  further comprising a cylindrical recess in which the thumb-engagement insert is positioned, wherein the cylindrical recess has a third diameter larger than the second diameter of the thumb-clearance recess so that the bowling ball is provided with an insert-supporting shoulder. 
     
     
         4 . The bowling ball of  claim 1  wherein the thumb-engagement insert has a lower interior portion with a frustro-conical shape. 
     
     
         5 . The bowling ball of  claim 4  wherein the lower interior portion is tapered at an angle of about 30° to about 60° relative to an axis of the insert. 
     
     
         6 . The bowling ball of claim wherein the insert is between about one inch and 1½ inches in length. 
     
     
         7 . A thumb-engagement insert for a bowling ball comprising:
 a cylindrical body;   a cylindrical upper interior portion; and   a frustro-conical lower interior portion.   
     
     
         8 . The insert of  claim 7  wherein the lower interior portion is tapered at an angle of about 30° to about 60° relative to an axis of the insert. 
     
     
         9 . A method of constructing a bowling ball comprising the steps of:
 drilling a first recess hole with a first diameter in a thumb position of the bowling ball;   drilling a second recess hole with a second diameter smaller than the first diameter so that the second recess hole is coaxial with the first recess hole so that an insert-supporting shoulder is formed; and   placing a thumb-engagement insert into the first recess hole so the insert is in contact with the insert-supporting shoulder.   
     
     
         10 . The method of  claim 9  further comprising the step of drilling the insert to fit a thumb of a particular bowler.