CDT Geometric Dimensioning & Tolerancing Flashcards

What is the purpose of a feature control frame in GD&T?

Answer: To convey the geometric tolerance for a feature

A feature control frame is a rectangular box on a drawing that communicates the type of geometric control, tolerance value, and applicable datums for a feature.

Which condition describes when a feature of size contains the least amount of material within its tolerance?

Answer: Least Material Condition (LMC)

Least Material Condition (LMC) is the condition where a feature contains the minimum amount of material, such as the smallest shaft or largest hole within tolerance.

Runout tolerance is always measured with the part:

Answer: Rotating about a datum axis

Runout is a composite control measured by rotating the part about the specified datum axis while a dial indicator contacts the controlled surface.

What is the difference between circular runout and total runout?

Answer: Circular runout is measured at individual cross-sections; total runout covers the entire surface

Circular runout controls variation at each individual cross-section independently, while total runout controls the entire surface simultaneously during full rotation.

Which GD&T symbol controls the taper or cone shape of a feature relative to a datum axis?

Answer: Angularity

Angularity controls the orientation of a surface or axis at a specified angle (other than 0° or 90°) relative to a datum.

When a GD&T symbol appears in a drawing without a datum reference, which controls can be applied independently without a datum?

Answer: Form controls such as flatness, straightness, circularity, and cylindricity

Form controls (flatness, straightness, circularity, cylindricity) control the shape of a feature intrinsically and do not require a datum reference.