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Author: Crystal Bemis

Rule #1 and Derived Median Line Straightness

by Crystal Bemis on May 30, 2023.

"Why doesn’t Rule #1 apply to the straightness of a Derived Median Line?" In this article, we look at both surface straightness and straightness of a feature of size to understand why Derived Median Line Straightness overrules Rule #1 of GD&T.

Sheet Metal Holes as Datum Features

by Crystal Bemis on May 16, 2023.

If I specify a hole in a practically thin feature, such as a piece of sheet metal, is this still considered a cylindrical datum? Is this a poor choice of datum? In this article, we look at an example to help us answer these questions.

Surface Finish and Flatness

by Crystal Bemis on May 15, 2023.

Surface finish and flatness both limit the amount of variation in a surface – one at the micro level and one at the macro level. Is it permissible to call out both on the same surface?

Virtual Condition vs Tolerance Zone

by Crystal Bemis on May 9, 2023.

In our video question line, our GD&T instructors answer questions submitted by our students. In this video, we answer the question, “Is the Virtual Condition the same as the Tolerance Zone?”

Meet the GD&T Basics Team: Molly Olson, GD&T Instructor

by Crystal Bemis on April 17, 2023.

Molly Olson is one of our expert GD&T Instructors, with a wealth of valuable real-world experience in quality control and inspection. She has spent nearly 20 years as a Quality Inspector and CMM Programmer and Operator across several different industries, including aerospace, firearms, robotics, and prosthetics.

Chamfer Dimensioning

by Crystal Bemis on November 10, 2022.

A chamfer is an edge feature commonly seen on part drawings, and consists of an angled cut on an internal or external edge of a part.

Fillets & Rounds

by Crystal Bemis on November 10, 2022.

Fillets and rounds are both radial edge features, with fillets applied to internal edges and rounds applied to external edges.

Break Edges Note

by Crystal Bemis on November 10, 2022.

“Break all sharp edges and remove all burrs,” is a common drawing note used to notify the manufacturer that the sharp edges and burrs produced by the manufacturing process must be removed from the part.

Knurling

by Crystal Bemis on September 19, 2022.

Knurling is a process used to create a pattern on the surface of a material by displacing or deforming the surface.

Keyseats and Keyways

by Crystal Bemis on August 1, 2022.

A keyed joint is used to ensure orientation or restrict rotational movement between parts, as in the case of joining a shaft with a coupling. We discuss how a keyed joint is made and inspected in this article.

Position Tolerance vs “True Position”

by Crystal Bemis on June 8, 2022.

Though many people refer to the GD&T Position symbol as "True Position," they are not the same thing. Read on to learn the difference between Position and True Position and how they work together to define the position of a feature.