“Right Diameter-First Cut” Lathe Datuming Probe

Abstract

A review of existing tool datuming techniques applied to lathes is made and their advantages and disadvantages outlined. Existing techniques suffer from one or more of three drawbacks. These are that the methods are firstly either susceptible to machine tool thermal growth resulting in a diametrical error of the workpiece or, secondly, the absolute position of the tool tip with respect to the spindle centre is not known. A third drawback with some techniques is that a trial cut has to be made followed by compensation of the radial position of the tool tip. A new device [1] is described which overcomes these drawbacks. It is a simple portable device that is loaded into the chuck of a machine tool. The device, known as a lathe datuming probe, consists of a datum cylinder whose diameter is accurately known. The mechanism of the lathe datuming probe enables the datum cylinder to be touch sensitive to engagement by the tool tip. A prototype probe has been constructed and tests carried out on a CNC lathe.