In a bilateral tolerance system used in engineering fits and limits, the permissible variation from the nominal (basic) size is provided on which side(s) of that nominal size?

Introduction / Context:

Tolerancing specifies allowable size variation to ensure interchangeability and functional fit. Bilateral and unilateral systems differ in how this variation is distributed relative to the basic (nominal) size.

Given Data / Assumptions:

• Limits and fits per standard practice (e.g., ISO system).
• Nominal size is the intended target dimension.
• Symmetric or asymmetric bilateral limits are both considered bilateral.

Concept / Approach:

In a bilateral tolerance, permissible deviation is allowed on both sides of the nominal size (e.g., ±0.02 mm or +0.03/−0.01 mm). In a unilateral tolerance, deviation lies on only one side (all plus or all minus) of the nominal.

Step-by-Step Solution:

Verification / Alternative check:

Dimensional callouts like 25.00 ± 0.02 mm or 25.00 +0.03/−0.01 mm are standard bilateral examples in drawings.

Why Other Options Are Wrong:

• One side of nominal or above nominal only: describes unilateral tolerances.
• Actual measured size options: tolerances are defined about nominal, not post-measurement sizes.

Common Pitfalls:

• Assuming bilateral must be symmetric; it may be asymmetric but still on both sides.

Final Answer:

both sides of the nominal size