Handed parts: Are right-hand and left-hand parts mirror images that are intended to be interchangeable, or are they opposite-handed and therefore not interchangeable?

Introduction / Context:
Handedness describes mirror-image counterparts (right-hand vs left-hand) in parts such as threads, levers, brackets, and housings. Recognizing that handed parts are not interchangeable prevents assembly errors and ensures correct function and ergonomics.

Given Data / Assumptions:

• “Right-hand” and “left-hand” imply mirror symmetry across a plane.
• Assembly interfaces often depend on handed geometry (mounting holes, flanges).
• Interchangeability requires identical geometry, which mirror parts do not have.

Concept / Approach:
Mirror images are congruent only after reflection (an operation not available in physical assembly without re-machining). As-manufactured parts preserve handedness; attempting to substitute the opposite hand usually misaligns features or reverses motion (as in thread direction).

Step-by-Step Solution:

Verification / Alternative check:
Assembly drawings and BOMs list separate part numbers for RH and LH components, underscoring non-interchangeability.

Why Other Options Are Wrong:
Claims that shims, bilateral tolerances, or “symmetric features only” restore interchangeability ignore the fundamental mirror reversal of geometry.

Common Pitfalls:
Ordering the wrong hand; flipping drawings without updating part numbers; assuming symmetry where it does not exist.

Final Answer:
Incorrect