Controls vs. Attributes Matrix Now Available PDF Print E-mail

One major difficulty in learning GD&T is remembering what, exactly, each control symbol actually controls. There are lots of guides available that do a good job of summarizing the shape and size of the tolerance zones for each symbol (two parallel planes, a cylinder, etc.) but when someone uses the words size, form, orientation, and location, they might be referring to geometric attributes, not the Y14.5 defined categories of controls.

For example, when you read that Rule #1 means that "size controls form" it means that size dimensions control the geometric attribute of form. The form control symbols (flatness, straightness, circularity, and cylindricity) also control the geometric attribute of form, but then so do the orientation control symbols (perpendicularity, parallelism, and angularity), but only under certain circumstances (when applied to surfaces without a tangent plane only modifier).

To help clarify the relationships, we've made available a PDF that you can download and print that shows how the categories of controls (size, form, orientation, location, runout, and profile) control the geometric attributes of size, form, orientation, and location. Check it out under "Free GD&T Downloads" and let us know what you think!


ASME-ISO-Comparison PDF Print E-mail

Checkout a couple of new resources that we welcome you to download on the differences between the ASME and the ISO GD&T standards. The first is a one-pager that describes the current "families" of standards.

The second is a two-pager that compares the similarities and differences between the current Y14.5 standard, older standards (we've found that the 1994 standard is still in wide-spread use, and many companies still have drawings created to the 1982 standard), and the ISO standard.

Go to Free Downloads now to check out these new resources. Thanks!


2009 Map of the GD&T World Now Available PDF Print E-mail

The 2009 Map of the GD&T World is available in two ways:


1. As a free PDF that you can download: Click on Free Downloads on the left menu.

Over 3,000 people have downloaded the 1994 PDF Map of GD&T, and we figured you might as well be downloading one that is in compliance with the ASME Y14.5-2009 GD&T Standard. Feel free to print it out and use it as a resource, and contact us with any questions or comments.

2. Also, we've put an interactive version of the map online for you to use a quick reference: Click on Interactive Map of the GD&T World on the left menu.

Thanks to all who have commented!

Bookmark this link ( so that the map is easily available from your computer as a quick reference.



Public Seminar Offerings PDF Print E-mail

We offer the following courses as custom onsite workshops (and every once in a while we get motivated to try to market a public workshop, so check back to see if we've got one scheduled!):

1- or 2-day Reading Engineering Drawings

3- 4- or 5-day Fundamentals of GD&T (Our Fundamentals incorporates what many companies split into two classes: "fundamentals" and "advanced" - we can pick & choose topics based on your applications.)

2- or 3-day Tolerance Stack Analysis Using GD&T

1- or 2-day GD&T Review (Begins with a test, then content areas that need review are explored. The rest of the time participants work in groups to apply GD&T to representative drawings that are from their world of parts.

We have run public seminars in Detroit, Dallas-Ft. Worth, Los Angeles, and Boston in recent years. We haven't finalized plans for 2014-2015 yet, so let us know if you'd be interested in attending a public workshop and the location. We'd really like to get critical mass to hold a class in Hawaii...

If your organization has five or more individuals who need training in GD&T or tolerance stack analysis, please contact us - we'd love to bring the training to you.


Reading Engineering Drawings PDF Print E-mail

Interpreting a technical drawing is an essential skill to anyone involved with the design, manufacturing, inspection, or procurement of products. It is prerequisite to fully understanding GD&T.

This 1-day Reading Engineering Drawings course is designed for those who need an introduction to drawings, including technicians, purchasing agents, new-hires, co-op students, interns, inspectors, quality assurance, managers and supervisors and anyone else who feels unfamiliar or intimidated by engineering drawings in the workplace.


Topics include:

•     The role of prints in industry
•     Types of graphic representation
•     Basic steps in reading a print
•     The "alphabet" of line types
•     Orthographic projection—visualizing the 3D part
•     Interpreting title block
•     Notes and revisions to a drawing
•     Auxiliary and section views
•     Dimensioning and tolerancing
•     Manufacturing specifications—screw threads, surface finish, etc.
•     Introduction to GD&T

All training is in accordance with ASME standards. You will be able to practice these concepts with many class exercises and evaluation of sample drawings. Participants are also encouraged to bring drawings to the class for discussion!

What is GD&T? PDF Print E-mail

GD&T (Geometric Dimensioning and Tolerancing) is a particular way of communicating dimensions and tolerances for size, location, orientation, and form. In North America, the current standard is ASME Y14.5-2009, which is very similar to ISO, DIN, JIS, and other standards used outside of the US. The basic idea of GD&T:

Geometric: A way of thinking about and communicating dimensions and tolerances for a product.

Dimensioning: Calculating, recording, and communicating desired values for size, location, orientation, and form.

Tolerancing: Calculating, recording, and communicating acceptable ranges for size, location, orientation, and form.

ASME Y14.5-2009 Update PDF Print E-mail

The long-awaited revision to the ASME Y14.5M-1994 standard is now available. You can buy the new version, ASME Y14.5-2009, from ASME at their website, It's $169 for either the print version or a PDF version. You save the $18 shipping by ordering the PDF version, but be prepared to load some software in order to view the PDF – it's protected and only works on one computer, the physical machine that you download and open it on. So if you have a desktop and a laptop, you'll want to download the file using the same machine that you plan to access the standard on.



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