CDT CDT Geometric Dimensioning & Tolerancing 1 — Questions and Answers
Question 1: Which GD&T symbol is used to control the straightness of a surface or axis?
- Flatness
- Straightness (Correct answer)
- Cylindricity
- Circularity
Correct answer: Straightness
Straightness is the GD&T symbol that controls how straight a surface line element or axis must be.
Question 2: What does the Maximum Material Condition (MMC) modifier mean when applied to a feature of size?
- The feature has the least amount of material
- The feature is at its nominal dimension
- The feature has the greatest amount of material within its tolerance (Correct answer)
- The feature is measured at room temperature
Correct answer: The feature has the greatest amount of material within its tolerance
MMC refers to the condition where a feature of size contains the maximum amount of material permitted by its tolerance, such as the largest shaft or smallest hole.
Question 3: Which datum reference frame axis is typically the primary datum in a three-plane datum reference system?
- The axis with the least contact points
- The axis established by the largest flat surface (Correct answer)
- Any axis selected arbitrarily
- Always the Z-axis regardless of part orientation
Correct answer: The axis established by the largest flat surface
The primary datum is typically established by the largest flat surface because it provides the most stable three-point contact with the datum reference frame.
Question 4: A true position tolerance of ⌀0.010 at MMC means the positional tolerance zone is a:
- Square zone of 0.010 × 0.010
- Cylindrical zone of diameter 0.010 (Correct answer)
- Linear zone of ±0.005
- Spherical zone of radius 0.010
Correct answer: Cylindrical zone of diameter 0.010
When a diameter symbol precedes the positional tolerance value, the tolerance zone is cylindrical with that diameter.
Question 5: Which GD&T control establishes both the form and the location of a feature simultaneously?
- Flatness
- Concentricity
- Profile of a Surface (Correct answer)
- Angularity
Correct answer: Profile of a Surface
Profile of a Surface is a composite control that can simultaneously control the form, orientation, and location of a surface.
Question 6: On a US engineering drawing, the default tolerance interpretation standard for GD&T is defined by which document?
- ISO 1101
- ASME Y14.5 (Correct answer)
- ANSI B4.2
- MIL-STD-31000
Correct answer: ASME Y14.5
ASME Y14.5 is the American national standard that defines GD&T symbols, rules, and tolerancing principles used on US engineering drawings.
CDT CDT Geometric Dimensioning & Tolerancing 1
Which GD&T symbol is used to control the straightness of a surface or axis?