GD&T Symbol 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 GD&T Symbol Interpretation flashcards as text
What does the profile of a surface symbol (an arc with no leader pointing to a plane) control?
Answer: All points on a surface relative to a true profile
Profile of a surface controls all points on a feature surface to lie within a tolerance zone defined by two offset boundaries around the true profile.
A feature control frame reads: ⌀0.005 M A B. What does the 'M' modifier mean in this context?
Answer: Maximum Material Condition — tolerance may increase as feature departs from MMC
The M (circle M) modifier stands for Maximum Material Condition, allowing a bonus tolerance as the feature departs from its MMC size.
Which GD&T symbol is used to specify that a hole's axis must lie within a cylindrical tolerance zone relative to a datum axis?
Answer: True position ⊕
True position (⊕) locates a feature's axis within a cylindrical (or two-parallel-plane) tolerance zone relative to specified datums.
What does a flatness callout of 0.002 mean on a machined surface?
Answer: All surface points must lie between two parallel planes 0.002 apart
Flatness requires all points on the surface to fall within a tolerance zone formed by two parallel planes separated by the stated tolerance value.
A drawing calls out perpendicularity of ⌀0.003 A on a pin. What shape is the tolerance zone?
Answer: A cylinder of diameter 0.003 perpendicular to datum A
When a diameter symbol precedes the tolerance value in a perpendicularity callout, the tolerance zone is a cylinder whose axis is perpendicular to the referenced datum.
Runout tolerance is always measured relative to what?
Answer: A datum axis established by one or more datum features
All runout tolerances (circular and total) are measured while the part rotates 360° about a datum axis specified in the feature control frame.
Which symbol controls the median line of a cylinder — not its surface — to be straight?
Answer: Straightness applied to the feature (axis straightness)
When straightness is applied to the feature (not the surface), it controls the derived median line of the cylinder to lie within a cylindrical tolerance zone.