Blueprint Reading & Technical Drawing Interpretation Flashcards
7 cards from real CNC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Blueprint Reading & Technical Drawing Interpretation flashcards as text
A drawing shows an angularity tolerance of 0.004 relative to datum A. What does this control?
Answer: The orientation of a surface or axis to fall within a 0.004-inch tolerance zone at the specified basic angle
Angularity is an orientation control that requires a feature to lie within a tolerance zone (two parallel planes or a cylinder) oriented at the theoretically exact basic angle to the datum.
On a CNC blueprint, what does a 'spotface' (SF) callout indicate?
Answer: A shallow flat circular area machined around a hole to provide a bearing surface for a fastener head
A spotface is a very shallow machined recess that creates a clean, flat, perpendicular seating surface for bolt heads or washers on rough cast surfaces.
When interpreting a CNC drawing with 'UNLESS OTHERWISE SPECIFIED: TOLERANCES ±.010 TWO PLACE DECIMALS, ±.005 THREE PLACE DECIMALS,' what tolerance applies to a dimension shown as 2.50?
Answer: ±.010
2.50 has two decimal places, so the general tolerance of ±.010 applies, giving an acceptable range of 2.490 to 2.510.
A cylindricity tolerance callout of 0.002 on a bore means:
Answer: All surface points of the cylinder must lie between two coaxial cylinders 0.002 inches apart in radial distance
Cylindricity simultaneously controls roundness, straightness, and taper—all points must fall within a zone bounded by two coaxial cylinders with a radial difference equal to the tolerance.
What information is found in the title block of an engineering drawing?
Answer: Part name, part number, material, scale, drawing number, revision, tolerances, and approvals
The title block is a standardized block containing identifying and administrative information needed to manage, manufacture, and inspect the part.
A drawing dimension reads Ø.750 -.000/+.002. For a CNC machinist boring this hole, what is the correct interpretation?
Answer: The hole diameter must be between 0.750 and 0.752 inches
The minus zero means the hole cannot be smaller than 0.750 (MMC for a hole), and the +0.002 sets the maximum at 0.752 (LMC).
What does the GD&T symbol for 'total runout' (two arrows on a circle) control that 'circular runout' does not?
Answer: Total runout controls the entire cylindrical surface simultaneously including taper, wobble, and eccentricity; circular runout checks only individual cross-sections
Total runout sweeps the indicator across the entire surface length during rotation, controlling all surface variations together, whereas circular runout only checks at individual cross-sectional slices.