GD&T Symbols and Rules 4

Question 1

A 'basic dimension' in GD&T is identified on a drawing by:

Accepted Answer

Enclosing the value in a rectangular box

Answer

Adding the letters 'BSC' next to the value

Answer

Underlining the dimension value

Answer

Placing it in parentheses

Question 2

What is the function of the 'tangent plane' modifier (T in a circle) in a GD&T callout?

Accepted Answer

The tolerance applies to a plane contacting the high points of the surface

Answer

The tolerance applies only to tangent line elements

Answer

The feature must be tangent to the datum

Answer

The surface must be measured with a tangential probe

Question 3

Which GD&T characteristic uses two coaxial cylinders as its tolerance zone?

Accepted Answer

Cylindricity

Answer

Concentricity

Answer

Total Runout (on a cylindrical surface)

Answer

Circular Runout

Question 4

The 'projected tolerance zone' symbol (P in a circle) is most commonly applied to:

Accepted Answer

Threaded holes or press-fit pins to control mating part interference

Answer

Flat surfaces requiring parallelism

Answer

Profile tolerances on curved surfaces

Answer

Runout measurements on rotating shafts

Question 5

In GD&T, the term 'virtual condition' for an external feature at MMC is calculated as:

Accepted Answer

MMC size plus the applicable geometric tolerance

Answer

LMC size minus the applicable geometric tolerance

Answer

MMC size minus the applicable geometric tolerance

Answer

LMC size plus the applicable geometric tolerance

Question 6

Which symbol instructs the inspector to measure a feature while it is rotating about a datum axis?

Accepted Answer

Circular Runout or Total Runout

Answer

Concentricity

Answer

Coaxiality

Answer

Cylindricity

Question 7

On a feature control frame, a datum letter followed by a material condition modifier (e.g., 'B(M)') means:

Accepted Answer

The datum shift allowance applies based on the actual mating size of datum feature B

Answer

Datum B is measured at its maximum material boundary

Answer

The datum B reference is optional

Answer

Datum B must be re-established for each measurement