GD&T Articles

by GD&T Basics 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,…

by GD&T Basics 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…

by GD&T Basics on January 6, 2021.

Surface finish can be a confusing subject, especially when it comes to units or the difference between Ra and Rz. In this article, we will provide a broad overview and answer some of the most commonly asked questions… What is Surface Finish? Surface finish is the term used to describe the texture of a surface,…

by on December 19, 2020.

What is a Composite Feature Control Frame?  A Composite Feature Control Frame (FCF) contains two tolerance zone frameworks. It is shown to be a composite tolerance because there is one geometric symbol that spans across the two frameworks. Figure 1 shows a Composite FCF controlling Position tolerance of a pattern of holes. The tolerance indicated…

by Brandon John on December 15, 2020.

Some of the most common questions that we receive at GD&T Basics is regarding the ASME GDTP Certification Exams. (Yes, you can become a certified GD&T expert!) Read on to learn more about the different exams and how to become certified in GD&T. You probably know what GD&T is and that it is important, but…