Patent ID: 6973738

Claim:
An apparatus for measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising: feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool; first shaft reference position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system; tool cutting edge position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the position of a cutting edge of a tool relative to a reference position of the spindle; and calculation means for calculating the coordinate position of the cutting edge of a tool in the coordinate system on the basis of the coordinate position of the reference position in the coordinate system measured by the feed shaft position reading means and the first shaft reference position measuring means and the position of the cutting edge of the tool relative to the reference position of the spindle measured by the feed shaft position reading means and the tool cutting edge position measuring means.