GD&T Position Tolerancing Calculations 4

Question 1

In a 3D tolerance stack, three features contribute ±0.10, ±0.15, and ±0.20 positional deviations along the same axis. What is the worst-case total deviation?

Accepted Answer

±0.45

Answer

Worst-case (arithmetic) stack = 0.10 + 0.15 + 0.20 = ±0.45 mm along that axis.

Question 2

Using RSS (Root Sum of Squares) for the same three deviations (±0.10, ±0.15, ±0.20), the statistical tolerance is approximately:

Accepted Answer

±0.27

Answer

RSS = √(0.10² + 0.15² + 0.20²) = √(0.01 + 0.0225 + 0.04) = √0.0725 ≈ ±0.27 mm.

Question 3

A pattern of 6 holes must assemble with 6 clearance fasteners. MMC of holes = 10.0 mm, fastener MMC = 9.6 mm. Using the fixed fastener formula, the position tolerance is:

Accepted Answer

⌀0.4

Answer

Fixed fastener tolerance = (MMC_hole − MMC_fastener) / 1 = 10.0 − 9.6 = 0.4; split between two mating parts gives ⌀0.2 each, but for a single part: ⌀0.4.

Question 4

For a floating fastener assembly, the position tolerance formula is:

Accepted Answer

T = (H − F) / 2

Answer

Floating fastener formula: each part gets T = (H_MMC − F_MMC) / 2, splitting the clearance equally between both mating parts.

Question 5

A true position callout without any modifier defaults to which condition under ASME Y14.5-2018?

Accepted Answer

RFS

Answer

Under ASME Y14.5-2018, RFS is the default implied condition when no modifier symbol (M or L) is shown.

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

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

GD&T Position Tolerancing Calculations 4