GD&T Position Tolerancing Calculations 5

Question 1

A CMM report shows a hole axis deviated 0.18 mm in X and 0.24 mm in Y from true position. The diametral position error is:

Accepted Answer

⌀0.60

Answer

Radial = √(0.18² + 0.24²) = √(0.0324 + 0.0576) = √0.09 = 0.30; diametral = 2 × 0.30 = ⌀0.60.

Question 2

Which of the following best defines 'resultant condition' for an external feature (pin) at MMC with position tolerance?

Accepted Answer

LMC + position tolerance

Answer

Resultant condition for an external feature = LMC + position tolerance, representing the worst-case outer boundary at the smallest actual size.

Question 3

When calculating position for a slotted hole (elongated feature), GD&T allows specifying two position tolerance values. What do the two values control separately?

Accepted Answer

Tolerance in the length direction and tolerance in the width direction

Answer

Two values allow a larger position tolerance along the slot's length direction and a tighter tolerance across its width, reflecting functional assembly requirements.

Question 4

A part has four tapped holes (fixed fastener situation) to mate with a cover plate. The clearance holes in the cover are ⌀6.5 mm (MMC) and the screws are ⌀6.0 mm (MMC). What position tolerance should each part receive?

Accepted Answer

⌀0.25 each

Answer

Floating fastener: T_each = (6.5 − 6.0) / 2 = 0.25 mm; each part gets ⌀0.25 position tolerance.

Question 5

A tolerance analysis requires that the total positional contribution of a feature be within ⌀0.8. If the feature is at actual size 20.3 mm with MMC = 20.0 mm and stated position of ⌀0.3 (M), does the feature pass?

Accepted Answer

Yes — total allowable is ⌀0.6, within ⌀0.8 requirement

Answer

Total allowable = ⌀0.3 + (20.3 − 20.0) = ⌀0.6; since ⌀0.6 ≤ ⌀0.8, the feature passes the stack requirement.

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

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

GD&T Position Tolerancing Calculations 5