Abstract: A method for sampling a workpiece and for retaining the sample in the workpiece so that it may be retrieved by using a semi-spherical cutting blade rotated about its central axis and articulated about an axis perpendicular thereto such that the cutting action follows a single arcuate path enabling a cut to be made in a workpiece which is relatively shallow and smooth, thereby providing under normal circumstances a non-destructive, partial-spherical recess in the workpiece sampled which does not have to be repaired before placing the workpiece back into service, while at the same time forming a sample of significant depth and size adequate for accurate analysis.