ASME GDTP Technologist study guide
ASME GDTP Technologist · Work through your exam, one topic at a time.
The GDTP Professional Certification is an ASME personnel credential that recognizes demonstrated understanding of geometric dimensioning and tolerancing (GD&T) principles as defined in the Y14.5 standard. ASME describes the program as one of its personnel certifications, alongside the QRO program, and its site notes that GDTP-2018 certification exams are open for registration. The ASME GDTP Technologist study guide has 8 sections and about 2,416 words.
01Fundamentals of GD&T and Y14.5: Concepts, Symbols, and Rules
Nearly every question on this exam reduces to reading one frame: geometric symbol, zone shape and value, material-condition modifier, and datum references in order of precedence. Know the five families cold - form (straightness, flatness, circularity, cylindricity), orientation (parallelism, perpendicularity, angularity), location (position, concentricity, symmetry), profile (line, surface), and runout (circular, total).
293 words, about 1 min02Datum Reference Frames, Datum Features, and Datum Selection
A datum feature is the actual surface or feature of size on the part; a datum is the theoretical plane, axis, or point derived from it; a simulator is the physical equipment (surface plate, chuck, mandrel, gauge pin) that establishes it. The three datums form a datum reference frame of three mutually perpendicular planes that removes six degrees of freedom.
308 words, about 2 min03Form Tolerances: Flatness, Straightness, Circularity, Cylindricity
Form tolerances constrain a feature to itself, so the four form controls never reference datums. Flatness places a surface between two parallel planes.
293 words, about 1 min04Orientation Tolerances: Parallelism, Perpendicularity, Angularity
Parallelism, perpendicularity, and angularity control the orientation of a surface, axis, or center plane relative to one or more datums, and they always require a datum. The zone is two parallel planes at the stated separation, or a cylinder when the tolerance is applied to an axis and carries a diameter symbol.
312 words, about 2 min05Location Tolerances: Position, Concentricity, Symmetry, and Bonus Tolerance
Position locates an axis, center plane, or surface using basic dimensions from the datums, with the tolerance stated in the feature control frame. For a hole the default zone is a cylinder whose diameter is the frame value, centered at true position.
302 words, about 2 min06Profile Tolerances: Line and Surface, and Their Application
Profile of a line controls each cross-sectional element independently between two parallel lines offset from the true profile. Profile of a surface controls the entire surface between two surfaces offset from the true profile.
302 words, about 2 min07Runout Tolerances: Circular and Total
Runout is the only control verified by rotating the part about a datum axis while an indicator contacts the surface. Circular runout is checked at each circular element separately.
307 words, about 2 min08Composite and Combined Controls, Virtual Condition, and Drawing Interpretation
Composite position uses a single geometric symbol with stacked segments. The upper segment locates the pattern to all the datums; lower segments control the internal location, that is feature-to-feature spacing, and orientation of the pattern, and may drop the locating datums.
299 words, about 1 min