Your Source for GD&T Training
Based on The GD&T Hierarchy

Tec-Ease, Inc. provides the most comprehensive GD&T training and coaching in the industry. Our GD&T courses are designed to keep the participant interested and engaged, while having fun.

Your Source for GD&T Software
and Computer Based Training

Tec-Ease, Inc. software packages are designed to help train and offer continued support to companies and employees in the industrial manufacturing field.

We offer On-Site Courses,
Public Seminars,
Webinars and Computer Based Training.

Stop Mixing Dimensions (#54)

(In accordance with the ASME Y14.5-2018 standard)
(In accordance with the ASME Y14.5-2009 standard)
(In accordance with Y14.5M-1994 standard)

PDF available for premium site members.

A recurring problem occurs when position tolerancing is used but the dimensions locating the features are not all basic. Below is a redraw of a print I recently received. The 20 and 80mm dimensions are not basic. In addition, this appears to be a symmetric part. The part could be set up two different ways (if datum feature A is not identified in some way, there are 4 possible ways to align the part). All dimensions locating position tolerance zones must be basic.

The drawing below solves both problems. Datums B and C are now center planes. The dimensioning is implied to be symmetric. The dimensions needed to locate the position tolerances are basic.

This tip is in accordance with ASME Y14.5M-1994, Y14.5-2009 and Y14.5-2018
This tip was originally released in May 2002.

Max the Tec-Ease mascot

Learn About Premium Today!

Back to Tips Tip added Sep 2022