34 34 each of these abutment surfaces extend effectively completely across the diameter of the tool holder as seen in fig8 but for only half of the width of the clamping slot 21 39 in addition to provide relief for the point of the cutter blade an axially located hole may be bored as at 37 34 and as in the embodiments of fig5 and 6 clamping bores 24 34 and 26 34 are provided to clamp the cutter insert such as 40 39 into the holder 20 39 this particular method of providing for an abutment surface facing the spade cutting blade automatically provides for the necessary relief for the cutting edges of the cutting blade and this cutting blade may be readily clamped into its holder the arrangement that is provided eliminates one loose part that may be advantageous in certain machine shop operations it should be understood that the angles m and n are chosen in the same fashion so that the included angle that was discussed as the included angle a will have the same geometry as that discussed in connection with the insert 30 as illustrated in fig3 in fig1 and 12 a modified spade drill holder 61 has a clamping slot 62 that is cut into one end of the holder on a diameter.