Single-point cutting tool geometry: defining the side relief angle In metal cutting (turning) with a single-point tool, which description correctly defines the side relief angle of the tool?

Introduction / Context:
Single-point cutting tool geometry uses standard angles (rake, relief/clearance, cutting edge and nose angles) to control chip flow, cutting forces, and surface finish. Understanding what each angle physically represents helps operators set up tools correctly and avoid rubbing.

Given Data / Assumptions:

• Conventional tool nomenclature per ASA/ISO with clearly defined rake and relief faces.
• Focus on the side relief (side clearance) angle measured on the side flank beneath the cutting edge.
• Tool set on center and cutting a typical turning operation on a lathe.

Concept / Approach:
Relief (clearance) angles prevent the flank from rubbing the newly machined surface. The side relief angle is measured on the side flank, whereas the end relief angle is measured on the end flank. Rake angles are measured on the tool face and should not be confused with relief.

Step-by-Step Solution:
Identify what is being compared: side flank vs. a reference plane perpendicular to the tool’s center line.Side relief angle = angle between the side flank under the point and a plane perpendicular to the reference (center) line at the point.This definition ensures clearance in the direction of lateral chip flow along the side cutting edge.

Verification / Alternative check:
Standard tool diagrams show separate gauges for end relief and side relief, each referenced to a perpendicular plane, confirming the stated definition.

Why Other Options Are Wrong:

• Back rake (A) and side rake (B) concern the face, not the flank.
• (D) uses a line rather than a reference plane, which is not the standard metrology basis.
• (E) relates to a different plan-view angle, not relief.

Common Pitfalls:
Confusing rake with relief; measuring in the wrong reference plane; setting too little relief causing rubbing and poor finish.

Final Answer:
The angle between the side flank surface immediately below the cutting point and a plane at right angles to the tool's center line at the point