GD&T Geometric Symbols & Notation 4

Question 1

What does the 'independency' symbol (circled I) indicate when applied to a feature of size?

Accepted Answer

The size and form tolerances are independent and do not interact

Answer

The independency symbol overrides Rule #1 (perfect form at MMC), allowing the form tolerance to be independent of the size tolerance.

Question 2

A GD&T 'Symmetry' callout controls:

Accepted Answer

The location of a feature's median plane relative to a datum plane

Answer

Symmetry (removed in ASME Y14.5-2009, retained in ISO) requires that the median points of a feature lie within a tolerance zone centered on a datum plane.

Question 3

On a GD&T drawing, a dimension value enclosed in a rectangular box (no text) signifies:

Accepted Answer

A basic (theoretically exact) dimension

Answer

A boxed dimension value (without the word BASIC) is the ISO method for denoting a theoretically exact basic dimension.

Question 4

The 'Least Material Condition' (LMC) modifier circled L is used to:

Accepted Answer

Apply additional tolerance when a feature is at its minimum material condition

Answer

The LMC modifier allows a geometric tolerance to increase as the feature departs from its least material condition, useful for ensuring minimum wall thickness.

Question 5

Which symbol on a feature control frame indicates a 'simultaneous requirement' is not in effect and features are verified independently?

Accepted Answer

SEP REQT (Separate Requirement) notation

Answer

Adding 'SEP REQT' (Separate Requirement) to a feature control frame means each callout is gauged independently rather than simultaneously.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

GD&T Geometric Symbols & Notation 4