Geometric Dimensioning and Tolerancing (GD&T)

Explain fundamental rule a in geometric dimensioning and tolerancing by detailing tolerance methods—direct, feature control frame for basic dimensions, and general notes—plus reference, maximum, minimum, and stock dimensions.

Define the fundamental rule e: drawings define a part without specifying manufacturing methods, and tolerance drives the manufacturing process from milling to finishing.

Fundamental rule i shows that a 90-degree angle is implied between perpendicular surfaces and hole axis on a 2d drawing, with tolerance defined by angular tolerance in the title block.

Explore fundamental rule j, where a 90 degree basic angle is implied for axes perpendicular to a surface when hole centers are located by basic dimensions on 2D orthographic drawing.

Explore fundamental rule k in geometric dimensioning and tolerancing, where zero basic dimensions arise when axis center planes are coincident under a geometric tolerance.

Rule l requires measuring all dimensions and tolerances at 20°C unless stated otherwise, because temperature changes affect diameter and length, necessitating compensation when 20°C measurement isn't possible.

Define a feature as any physical portion of a part, such as surfaces, holes, or slots, and learn how multiple features form complex or interrupted features in GD&T.

Explore the feature of size, a dimension tied to two parallel opposed surfaces, and how the 1994 and 2009 standards classify it into regular and irregular features in GD&T.

Explore the regular feature of size across cylindrical, spherical, and circular elements with opposing parallel surfaces. Use vernier calipers to identify internal and external features versus non feature of size.

Learn about irregular feature of size in geometric dimensioning and tolerancing, covering type a and type b irregular features, envelope measurements with vernier caliper, and counterparts to determine size.

Explore geometric dimensioning and tolerancing by identifying regular and irregular features of size, type a and type b, with labeled surfaces, dimensions, and envelope.

Explore material conditions in GD&T, including maximum material condition (MC) and least material condition (LMC), and regardless of feature size (RFS), with examples on feature size vs non-feature of size.

Identify actual local size as the measured dimension at any cross-section normal to the axis, showing variation along the part but remaining within specified upper and lower limits.

Explore the actual mating envelope, the smallest envelope that touches the high points of an external feature and the largest envelope for an internal feature, illustrated with an expanding pin.

Learn how the feature control frame, a box with two to five compartments, uses a geometric symbol and a tolerance value with modifiers and datums to control features on drawings.

Understand rule number one in GD&T, including the envelope principle and perfect format concept, with maximum and least material condition and form controls such as straightness, flatness, circularity, and cylindricity.

Identify exemptions to rule one in geometric dimensioning and tolerancing, including non-rigid parts and raw stock materials, and learn when rule one cannot be applied.

Rule number two, all applicable geometric tolerance rule, applies regardless of feature size or material boundary when no modifiers exist in the feature control frame, with MMC or LMC modifiers.

Apply straightness as a form control to an axisymmetric cylindrical surface, using a 0.2 tolerance with two parallel lines within size limits and the maximum material condition envelope.

Assess straightness with a dial indicator on a surface plate, distinguishing straightness error from taper error via full indicator movement, verified by a slip gauge or gauge wire.

Apply straightness control in gd&t terms to a prismatic surface using direction-specific line elements, with 0.05 and 0.2 tolerances, and verify taper with a dial indicator.

Apply straightness onto a feature of size to control axis bend, align the feature control frame with dimension line, and use the diameter modifier to create a cylindrical tolerance zone.

Create a dynamic tolerance diagram for straightness by plotting 18.4 to 18.0 sizes with increment 0.1, apply maximum and least material condition, and read tolerances from 0.4 to 0.8.

Explore flatness as a GD&T surface control, applying to surfaces with a two parallel planes tolerance zone, waviness peak-to-valley not more than 0.2, and three-dimensional checks.

Tilt to compensate taper with slip gauge to level top surface; verify flatness with a dial indicator across length and width, keeping full movement under 0.1.

Apply flatness to a feature of size on a prismatic part's center plane, using a three-dimensional tolerance zone of two parallel planes one nanometer apart, at maximum material condition.

Apply circularity as a form control in GD&T to the axisymmetric surface circular profile, using a feature control frame with two coaxial circles and three-point measurement.

Apply circularity verification techniques in GD&T using a dial indicator and rotation to measure circularity error across cross sections, and compare graph sheet plotting with computer-based plots.

Master cylindricity as a three-dimensional form control using two coaxial cylinders to govern straightness, circularity, and taper, with three-point verification and size limits.

Verify cylindricity by rotating component with a dial indicator to check circularity, taper, and straightness; for micron tolerances, use machine-table equipment to plot a cylindrical surface and determine cylindricity error.

Define datum as a theoretical reference, relate datum feature on the part to a datum feature simulator, and create a simulated datum plane for primary, secondary, and tertiary datums.

Identify how datum reference frames establish primary, secondary, and tertiary datums to arrest all six degrees of freedom and serve as the measurement origin in GD&T.

Learn the 3-2-1 principle for datum planes: primary requires three points of contact, secondary two, tertiary one, for planar features on prismatic parts to achieve a stable condition.

Explore planar datums in GD&T and how a planar datum surface acts as primary datum. Learn datum feature symbols and simulators, and how they arrest one translation and two rotations.

Define the width datum as the center plane of a prismatic part, arresting one translation and two rotations with a datum feature simulator and illustrating with datum symbols.

Explore axis datum in gd&t, detailing datum feature symbols and extension lines, and illustrate how a collet fixes the axis to arrest four degrees of freedom.

Examine spherical surface as a datum in GD&T, control the datum point, and note that translation is restricted while rotations about the three axes remain free.

Using a conical surface as a primary datum arrests five degrees of freedom in axisymmetric parts by fixing three translations and two rotations, leaving one rotational degree of freedom active.

Linear extrusion data defines a primary datum, with two planes forming the datum reference frame to arrest five degrees of freedom, leaving only vertical translational movement.

Shows how a complex feature can serve as a primary datum, with three planes forming the datum reference frame and the datum feature simulator arresting all six degrees of freedom.

Explore datum targets in GD&T, including points, lines, and areas, and learn how the datum target identification symbol encodes their position. Apply the 3-to-1 principle and movable datum targets.

Angularity, a type of orientation control in GD&T, regulates the angular relation between features using a datum, for angles other than 0 or 90, within parallel planes 0.2 m apart.

Control angularity of center plane, a feature of size, to 60 degrees relative to datum, within parallel planes 0.2 apart, using maximum and least material condition modifiers for bonus tolerance.

Demonstrates applying angularity to a hole axis within a 0.2 cylindrical tolerance zone, enabling axis variation around 60 degrees and using material condition modifiers for added flexibility.

Verify angularity with a sine bar at 30 degrees, slip gauges, and a surface plate; use the datum feature simulator and dial indicator to check flatness and angularity.

Demonstrates verifying perpendicularity to a datum using a surface plate and dial indicator, with flatness and height difference limited to 0.1 across two parallel planes at 90 degrees.

Explore perpendicularity on a feature of size, focusing on a center plane tied to datum a with a 90-degree orientation, and note MMC/LMC options after the tolerance.

Apply perpendicularity to a feature of size axis to maintain a 90-degree relation to datum plane A, using a 0.4 cylindrical tolerance zone with a diameter modifier.

Control parallelism to keep a surface at zero degrees to the datum surface using two parallel planes 0.1 apart, with surface deviations not exceeding 0.2 and taper limited to 0.1.

Learn parallelism control in GD&T by the center plane of a slot referenced to datum E, kept between two parallel planes 0.2 M apart with the maximum material condition modifier.

Explore parallelism of a feature of size axis using a datum axis and cylindrical tolerance zone, keeping axis parallel to zero angle, and apply MMC and LMC for bonus tolerance.

Discover how the ASME 14.5 2009 alternate practice replaces perpendicularity and parallelism with angularity for orientation control, clarifying datum relations and applying angularity to any angle.

Convert coordinate dimensions to a basic dimension, apply a position tolerance with a datum framework, and establish a cylindrical tolerance zone (1.4 diameter) for hole location and orientation.

Learn to verify positional tolerance under maximum material condition by calculating true position, understanding tolerance zones, and using paper gauge or Excel sheet methods to accept or reject holes.

Explore concentricity in gd&t, using cylindrical tolerance zone to align cylinder axis with datum axis; learn why positional tolerance replaces concentricity and how mmc and lmc add flexibility.

Symmetry is explained as a location control, using center planes and derived median points to test coplanarity. ASME removed symmetry from the 2018 14.5 standard, leaving only tolerance of position.

Radial runout, or circular runout, controls circularity, perpendicularity, and concentricity with the datum axis inline with the feature axis. Check with a dial indicator in one setup, rotating the part.

Explore total runout, a form control for cylindrical surfaces that enforces cylindricity, parallelism, and concentricity with a datum axis, not applicable to taper surfaces, checked with a dial indicator.

Demonstrate applying total runout and radial runout on axisymmetric parts and faces to control cylindricity and flatness, using datum B as primary and A as secondary to guide orientation.

Explore profile controls in GD&T, including optional datums, related versus individual features, and how profile controls govern 3D contours, size, orientation, and location for axisymmetric and prismatic parts.

Explore profile of a surface with equally disposed tolerance to control size, form, orientation, and location relative to datums A, B, and C.

Explore the between modifier in gd&t, defining the profile of a surface between points a and b, for planar, cylindrical, or taper profiles.

Understand unilaterally disposed inside profile tolerancing, keeping maximum size 60 with a lower limit 59.6, and controlling form, orientation, and location relative to datums A and B.

Illustrates profile unilateral outside in GD&T, with lower size 60 and upper limit 60.4 within a 0.4 boundary referenced to datum A and B. It shows adding material, not removing.

Understand the profile unequally disposed modifier in gd&t, with size limits 60.1 to 59.7 and a total tolerance of 0.4, split into 0.1 outside and 0.3 inside between parallel planes.

Define the profile of a line as a GD&T symbol where the profile line lies between two parallel boundaries 0.2 m apart, governing form, orientation, and location.