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Category: Inspection of GD&T

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

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.

Radial Hole Pattern as a Datum Feature

by Crystal Bemis on May 27, 2024.

In this Question Line video, Jason responds to a question regarding radial hole patterns as datum features. He discusses how to set up the datum reference frame, how the datum reference frame controls degrees of freedom, and how to apply the Maximum Material Boundary.

How to Inspect True Position at an Angle

by Crystal Bemis on April 29, 2024.

When a hole is being controlled with position, the primary datum is often the surface that the hole originates from and the secondary and tertiary datums are perpendicular or parallel to the primary datum. However, this is not always the case. In this video, Jason walks through an example drawing to show us how to inspect a hole that is at an angle with respect to the primary datum.

Measuring Runout and Circularity with V-Blocks

by Crystal Bemis on April 1, 2024.

V-Blocks are popular tools used with manual inspections, but come with a unique pitfall that can impact the accuracy of measurements. In this video, Jason walks through the potential issues associated with using V-Blocks and how they can affect measurements of circularity and runout.

Profile Inspection: Vectors in CMM Measurement

by Crystal Bemis on March 4, 2024.

Coordinate Measuring Machines (CMMs) are essential tools for obtaining precise measurements. However, to ensure accurate measurements, it is crucial to understand how to use them correctly. In this video, Jason explains the importance of recognizing and utilizing appropriate vectors when inspecting a profile or irregular surface with a CMM probe.