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Category: Inspection of GD&T

Articles related to inspection of engineering prints and interpretation of GD&T for inspection purposes

Irregular Features as Datum Features

by Crystal Bemis on July 7, 2025.

In this Question Line video, Jason explains how an irregular feature like a hexagon can serve as a primary datum feature and discusses how this part could be inspected – touching on gage design for manual inspection and point cloud analysis using a CMM.

Dimensions Identified for Inspection

by Crystal Bemis on June 30, 2025.

What does it mean when a dimension is circled on a drawing—and how does it impact manufacturing? In this video, Jason explains the informal use of ovals as quality control symbols and what it means for how parts are made and inspected.

Separate Requirements at MMB

by Crystal Bemis on June 2, 2025.

In this video, Jason explains when simultaneous requirements apply and how the “separate requirements” note affects inspection, sharing examples that illustrate reasons for using each approach.

Significant Figures and Their Effects on Inspection

by Crystal Bemis on March 17, 2025.

In this Question Line video, Jason discusses the role of significant figures in identifying tolerances for dimensions with unspecified tolerances. He also walks through an example of how to determine the required accuracy of the measurement equipment according to the ASME Y14.43 standard.

Continuous Features vs Pattern Features

by Crystal Bemis on February 24, 2025.

In this Question Line video, Jason compares two similar part drawings - one containing the Continuous Feature symbol and the other having a simultaneous requirement for a pattern of features - and discusses how the inspected values would be reported.

Related vs Unrelated Envelopes

by Crystal Bemis on January 13, 2025.

In this Question Line video, Jason explains the difference between the related and unrelated actual mating envelope and walks through an example drawing to explain when and how they are used to inspect a feature.

Profile of a Surface with No Datums

by Crystal Bemis on January 6, 2025.

In this Question Line video, Jason walks through a few examples to show us the difference between profile of a surface with and without datums referenced in the feature control frame and how that affects the reported deviation.

Effects of Larger Tolerance Values

by Crystal Bemis on November 11, 2024.

In this Question Line video, Jason discusses a drawing that has a tight tolerance on the location of two holes that relate back to datum features that have much larger form control tolerances.

The Importance of Qualifying Datums

by Crystal Bemis on November 4, 2024.

In this Question Line video, Jason explains how datums are qualified and the difference between how CMMs and physical datum simulators set up the datum reference frame for a manufactured part.

Size Dimensions to Avoid

by Crystal Bemis on September 30, 2024.

In this Question Line video, Jason explains why the 2018 revision of ASME Y14.5 does not permit locating the distance between stepped surfaces with a size dimension. He also explains how utilizing datums and profile eliminates that ambiguous dimension from being applied and how to report that measurement to get the most direct tolerance between the stepped surfaces.

True Position and Diametric Deviations

by Crystal Bemis on September 23, 2024.

In this Question Line video, Jason answers questions regarding True Position and how to calculate diametric deviations. He discusses the difference between "True Position" and "Position" and walks through the process of determining whether the part passes inspection.

Reverse Inspections of Orientation

by Crystal Bemis on August 22, 2024.

In this Question Line video, Jason answers a question about reverse inspection of orientation and walks through an example to explain why you should not deviate from the inspection criteria given in the feature control frame.

Composite Profile Control

by Crystal Bemis on June 3, 2024.

In this Question Line video, Jason discusses a composite feature control frame controlling profile tolerance. He walks through through the user submitted examples to explain the controls of each frame.