2D Drawing Representation — Definition Check In technical drawing terminology, is a counterbore defined as a cylindrical recess around a hole that is machined to seat a bolt head or nut flush below the surface, typically specified by symbol, diameter, and depth?

Introduction / Context:
A counterbore is a common feature in mechanical drawings and shop practice. The purpose is to allow a bolt head, socket head cap screw, or nut to sit below or flush with a part surface to avoid interference with mating parts, sliding surfaces, or safety covers. This question checks whether the definition that a counterbore is a cylindrical recess around a hole used to receive a bolt head or nut is accurate. It also tests recognition of the way such features are specified on drawings using standards compliant notation and dimensions.

Given Data / Assumptions:

• The base hole is already present or will be drilled through to allow the fastener shank to pass.
• The recess is cylindrical with a flat bottom and a diameter larger than the shank hole.
• Dimensioning normally includes counterbore diameter and depth, sometimes symbolized with the counterbore mark.

Concept / Approach:
A counterbore differs from a countersink. A countersink is a conical recess used for flat head screws, while a counterbore is a cylindrical pocket for hex heads, socket heads, or nuts. The definition in the stem matches the cylindrical, flat bottom geometry and the intended function of seating hardware below the surface.

Step-by-Step Solution:
1) Identify geometry: cylindrical recess with flat bottom concentric to the through hole.2) Identify purpose: to clear and seat a bolt head or nut so that the top surface remains unobstructed.3) Check standards usage: drawings specify counterbore symbol, diameter, and depth along with the hole diameter.4) Compare with alternatives: countersink is conical; spotface is shallow planar cleanup around a hole.

Verification / Alternative check:
Handbooks and drafting standards show callouts such as: hole diameter, counterbore symbol, counterbore diameter, and counterbore depth. Shop practice for socket head cap screws routinely uses counterbores for clearance and safe assembly.

Why Other Options Are Wrong:
Incorrect conflicts with standard definitions. Partially correct and Context-dependent add qualifiers that are not necessary for the core definition. Not enough information is inapplicable because the geometric description is complete and unambiguous.

Common Pitfalls:
Confusing counterbore with countersink; forgetting to specify depth; omitting tolerance or finish requirements for the recess bottom when needed.

Final Answer:
Correct