AIT Technical Drawing 4 — Questions and Answers
Question 1: What does a circle with an 'X' through it (target point symbol) represent in GD&T?
- A rejected or out-of-tolerance feature
- A datum target point used to establish a datum plane (Correct answer)
- The center of a bolt-hole pattern
- A blind hole that does not go through the part
Correct answer: A datum target point used to establish a datum plane
Datum target points are specific, controlled contact points used to simulate datums on irregular or uneven surfaces during inspection.
Question 2: In an isometric drawing, the three principal axes are drawn at what angles relative to horizontal?
- 0°, 45°, and 90°
- 30°, 90°, and 150° (making 30° angles with horizontal for the two receding axes) (Correct answer)
- 45°, 90°, and 135°
- 60°, 90°, and 120°
Correct answer: 30°, 90°, and 150° (making 30° angles with horizontal for the two receding axes)
In isometric projection, the two receding axes are drawn at 30° above horizontal, with the vertical axis at 90°, giving equal emphasis to three faces.
Question 3: What is the function of an extension line in a technical drawing?
- To extend a visible edge line beyond the view boundary
- To connect the dimension line to the feature being dimensioned (Correct answer)
- To indicate a surface that continues beyond the drawing border
- To show the path of a cutting plane
Correct answer: To connect the dimension line to the feature being dimensioned
Extension lines extend from the edge of a feature to provide a reference point for the dimension line, which carries the measurement value.
Question 4: A counterbore is represented on a drawing with which symbol prefix?
- ⌴ (square with one open side)
- ⌴ (counterbore symbol — flat-bottomed recess symbol) (Correct answer)
- ∨ (countersink symbol)
- ⌀ (diameter symbol)
Correct answer: ⌴ (counterbore symbol — flat-bottomed recess symbol)
The counterbore symbol (a square U-shape) precedes the diameter and depth callout of the flat-bottomed recess that accommodates bolt heads.
Question 5: Which line type is used to represent the cutting plane in a section view?
- A thin continuous line
- A thick dashed line (long dashes with short dashes at ends and arrows)
- A thin chain line (alternating long and short dashes) with thick ends and arrows (Correct answer)
- A thick continuous line with hatch marks
Correct answer: A thin chain line (alternating long and short dashes) with thick ends and arrows
The cutting plane line is a thin chain line that becomes thick at the ends where arrows indicate the viewing direction for the section.
Question 6: What does 'true position' control in GD&T?
- The exact surface finish required at a specific location
- The allowable variation in location of a feature from its theoretically exact position (Correct answer)
- The perpendicularity of a hole axis to a datum surface
- The maximum size deviation of a cylindrical feature
Correct answer: The allowable variation in location of a feature from its theoretically exact position
True position defines a tolerance zone (cylindrical or parallel planes) centered on the theoretically exact location of a feature.
Question 7: When a drawing note states 'UNLESS OTHERWISE SPECIFIED, ALL TOLERANCES ±0.010', this tolerance applies to:
- Only the dimensions shown without any individual tolerance (Correct answer)
- All dimensions on the drawing including those with their own callouts
- Only the overall length and width dimensions
- Threaded features and hole diameters only
Correct answer: Only the dimensions shown without any individual tolerance
General tolerance notes apply as a default to any dimension that does not already have a specific tolerance assigned to it.
AIT Technical Drawing 4
What does a circle with an 'X' through it (target point symbol) represent in GD&T?