What results from positioning the cutting tool tip below the centerline for facing operations?

What results from positioning the cutting tool tip below the centerline for facing operations?

• A. Nib at the center
• B. Clearance notch
• C. Center punch mark
• D. Centerline shift

Answer: (A)

When the cutting tool tip is placed below the centerline during a facing pass, the end of the work is cut with the tool’s edge entering behind the axis. This offset path leaves a small protrusion at the exact center of the face, known as a nib. The geometry of the cut doesn’t remove material evenly at the center when the tool is below center, so a tiny nub remains rather than a perfectly flat center. To get a clean center during facing, you set the tool on or very near the centerline (or slightly above). The other possibilities describe different features that arise from other conditions or operations: a clearance notch is a feature formed by edge clearance rather than center influence, a center punch mark comes from a marking operation, and a centerline shift indicates misalignment of the axis rather than the end-face result from tool height.

When the cutting tool tip is placed below the centerline during a facing pass, the end of the work is cut with the tool’s edge entering behind the axis. This offset path leaves a small protrusion at the exact center of the face, known as a nib. The geometry of the cut doesn’t remove material evenly at the center when the tool is below center, so a tiny nub remains rather than a perfectly flat center. To get a clean center during facing, you set the tool on or very near the centerline (or slightly above). The other possibilities describe different features that arise from other conditions or operations: a clearance notch is a feature formed by edge clearance rather than center influence, a center punch mark comes from a marking operation, and a centerline shift indicates misalignment of the axis rather than the end-face result from tool height.