So often in using GD&T, people are worried about using it correctly. And this can certainly be a valid question – geometric tolerancing consists of symbols and rules for how to use them. But we also need to remember that GD&T is a language for communicating design requirements. And like any other language, there may […]
Here’s another common question that comes up in a GD&T class: Suppose we are applying a position tolerance to a hole. It would typically have a diameter symbol in front of the number, as in the first example below. But what if we omit the diameter symbol in front of the number, as in the […]
Another question came in recently, having to do with basic dimensions and their use with datum targets. If you are up to speed on GD&T, you should know that a basic dimension is any number enclosed in a box:
The purpose of this is to show a theoretical dimension, without any tolerance. (Even a general title block tolerance does […]
If you are familiar with GD&T, you’ve probably heard of “virtual condition.” It is a number that represents a worst-case combination of a feature’s size along with its geometric tolerance. For instance, suppose we have the following example of a hole, with a size tolerance of 6 ± 0.2 mm: The worst case would be […]
There’s more to learning GD&T than just knowing the symbols. There is also a unique vocabulary—sometimes GD&T terms mesh with everyday usage, but sometimes a word can have a very specific meaning in geometric tolerancing.
Here are some examples:
The symbol circularity is sometimes called roundness. The two terms are synonymous, but the ASME standard uses circularity.
The […]
Here’s a question I received at the beginning of a recent GD&T training session. Often I’ll ask participants if there is anything in particular that they are looking to get out of the training. One gentleman didn’t hesitate:
“I’m here to learn why we shouldn’t use the concentricity symbol. No one has been able to tell […]
In this blog we’ll feature some common areas of discussion in GD&T, ranging from the technical nuances of the GD&T symbols to how to convince others that geometric tolerancing does not make a part more expensive to manufacture. You’ll also find out information about our upcoming seminars and updates on revisions to the Y14.5 […]
