tool tip 46 so that when the tool holder 12a is properly mounted on the respective cross slide 21 in the machine tool the end of this bolt 59 may engage the reference surface 16 or 77 to establish the tool tip 46 in the proper desired gaged position this will establish the desired tool tip cutting length of the workpiece 17 with these three mutually perpendicular distances preset in the fixture 11 then the nuts 39 may be loosened and the tool holder 12a removed and mounted on the desired cross slide 21 the key 40 will engage the t slot 22 on such cross slide to establish the desired gaged distance 71 the lower surface of the tool holder 12a resting on and being secured to the mounting surface of the cross slide will assure that the tool tip 46 in its line of movement will intersect the respective spindle axis the end of the bolts 59 engaging the reference surface 16 or 77 will establish the desired axial length of the workpiece up to the point of cutting by the tool tip 46 when the tool holder is an upside down tool holder 20b a very similar procedure for establishing the three mutually perpendicular gaged dimensions is followed in such case the tool holder 12b will be that as shown at the left portion of fig1 and 2 with the tool 20b mounted upside down the tool tip 46 in that case is.