files 104 106 108 are arranged in an alternative manner for example file 104 may include multiple cutting segments 110 separated by non cutting segments 112 located along working portion 114 file 106 may include cutting segments 116 and non cutting segments 118 located along working portion 120 so that a non cutting segment 118 is located at distal end 121 working portion 120 extends over a greater portion of file 106 than working portion 114 of file 104 additionally the lengths of cutting segments 116 and non cutting segments 118 may vary so that they may overlap with cutting segments 110 and non cutting segments 112 of file 104 file 108 may have cutting segments 122 and non cutting segments 124 located along working portion 126 which extends over a greater portion of file 108 than working portion 120 of file 106 or working portion 114 of file 104 a non cutting segment 124 is located at a distal end 128 in a manner similar to files 104 and 106 the length of cutting segments 122 and non cutting segments 124 may vary so that they may overlap with cutting segments 116 and non cutting segments 118 of file 106 and cutting segments 110 and non cutting segments 112 of file 104 the cutting segments 110 116 122 of individual files 104 106 108 are arranged so that when taken together they effectively form one continuous cutting segment covering the entire working portion 126 the staggered cutting segments and non cutting segments.