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.

Add a Note to Expand a Pattern for Composite Tolerancing (#223)

(In accordance with Y14.5M-1994 standard)

PDF available for premium site members.

Some folks think that composite tolerancing cannot be applied to a pattern of holes that have different sizes. When they have a group of holes of different sizes to control as a pattern it is not uncommon to locate one hole, make it a datum feature and control the other holes relative to that new datum feature. In this case, to guarantee a close fit, a refinement of perpendicularity is also required. Technically, this approach is OK. However, it does require a new set-up to inspect the part as well as the additional perpendicularity tolerance. The first drawing shows this approach.

Another approach is shown on the second drawing. Here all three holes are made a single pattern by the note, 3 HOLES. This approach gives the desired fit in the assembly while eliminating a set-up to establish an auxiliary datum reference frame and an additional inspection of the perpendicularity refinement on the larger hole.

Max the Tec-Ease mascot

Learn About Premium Today!

Back to Tips Tip added Aug 2008