In our last blog post, we looked at the six common tolerance zones that appear in today’s engineering drawings. While these six make up the broad majority of tolerance zones in geometric dimensioning and tolerancing (GD&T), you may encounter another zone in a given tolerance scheme—the spherical tolerance zone. The American Society of Mechanical Engineers […]

GD&T is a convention that gives the engineering world a tool that enables designed components to have both an unlimited variety of both geometric definition and tolerance. Consequently GD&T is about many things but it is ultimately about the disposition and appraisal of tolerance zones. This month our definition of terms will be about tolerance […]

Today our definition of terms will focus on “actual local size.” This term refers to a group of values that can be assessed and applied to any feature of size, values that establish the small and sometimes minute irregularities about a feature’s geometry. To understand what this means we first need to go back to […]

In the world of engineering and manufacturing, we say that GD&T gives us the ability to explicitly describe both nominal geometry and its allowable departure or tolerance from that nominal value. One side of the convention allows for the definition of the geometry and the other allows for the definition of tolerance. Accomplishing the definitions […]

Today our featured GD&T term is “features,” which includes “features of size.” But before we jump into this we need to talk about a basic term or thing or maybe we’ll call it a concept, which is the term part. In GD&T a part needs to be thought of as an item, or two or […]

In GD&T basic dimensions used to be a fairly simple thing to define. However, today, among other things, “Basic dimensions” are numbers on an engineering drawing that represent values of size in whatever the measurement system being used on the drawing is. Those values are used to describe the theoretically exact size, profile, orientation or […]

Today we’re going to look at the concentricity control. This control is used a lot in a variety of situations that involve coaxial relationships. The definition states that concentricity controls ‘all’ diametrically opposed elements of a figure of revolution. Breaking Down the Basics Let’s break that down and look at a few rules for this […]

Today I want to talk about a common definition for something we all talk about when the subject of GD&T comes up. I think it’s safe to say that the vast majority of people reading this series earn their livings on the floors of American factories. We design, machine, assemble, weld, measure, probe, form, punch, […]