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Category: Inspection of GD&T

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

Circularity, Rule #1, and How to Report

by GD&T Basics on February 12, 2021.

This video is in response to a question that we received on our question line from Amber. Amber asked us if the tolerance value for circularity can be obtained by subtracting the upper limit of diameter from the lower limit of diameter and dividing it in half. The short answer is no; that method does not provide the correct value. We will...

What is a Profilometer?

by GD&T Basics on February 12, 2021.

Ever wonder how surface finish is measured? For inspection, we use a device called a Profilometer.  In this article, we will show you how profilometers work and highlight their advantages and limitations. What is a Profilometer & Why is it Used? A profilometer is an instrument used to measure the profile and surface finish of a surface.  On a small...

Basic Dimensions and How to Report

by Brandon John on January 27, 2021.

In this video, Brandon discusses basic dimensions and why they should not be recorded on an inspection report. What Are Basic Dimensions? Basic dimensions describe the theoretically exact location, orientation, size, or profile of a feature or datum target. Because basic dimensions are theoretically perfect dimensions, there are no tolerances associated with them. A basic dimension is noted as a dimension with a box...

CMM Inspection Basics

by Seth Elder on January 18, 2021.

Do you know how dimensions and tolerances for complex parts are measured?  Often, a coordinate measurement machine or CMM is used.  In this article, we will look at different types of CMM’s and discuss how they work and when they are used.     What is a Coordinate Measuring Machine? A coordinate measuring machine is an instrument that is used to collect measurements of three-dimensional objects.  A CMM consists of a structure that moves in three dimensions, a probe attached to...

Profile Deviation Reporting

by Brandon John on January 13, 2021.

This video is in response to a question that we received on our question line from Brandon.   The question is as follows: “I have profile tolerance on a flat surface of 0.2 mm with respect to 3 datums.  Now measuring with a CMM, I get deviations to the negative and positive side of nominal.  For example, I get (-0.07mm) min...