When an “S” is present in the feature control frame, does this refer to the simulated datum?

Thanks,

Mike P.

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Hi Mike,

The circled S means regardless of feature size. It is from the ANSI Y14.5-1982 Standard.

Thanks for your question.

Roy Cross
ETI Dimensional Engineering Mentor

Q – Can you please explain the meaning of the following tolerance symbol? Which type of standard is this, ASME or ISO?

Edward C.

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Hi Ed,

The profile tolerance does not adhere to either the current ISO or ASME Y14.5 standards. Neither standard permits the word “BILATERAL” in the feature control frame. Also, both standards require that the geometric symbol be placed in the first compartment and the tolerance value in the second compartment, followed by the datum references in the third, fourth, and fifth compartments, if applicable.

Thanks for question,

Alex

ETI is offering special pricing on two of our best reference materials. Both items are valuable resources that will help you transition to the new ASME Y14.5-2009 Standard.

The Ultimate GD&T Pocket Guide and the
ASME Y14.5M-1994 to ASME Y14.5-2009
New Features Comparison Chart Set

Until February 28, 2010, for every three pocket guides your purchase, you’ll get an additional pocket guide free. For every three chart sets you purchase, you’ll receive one additional set free. Web orders only.

Sorry, no other discounts apply. Order today and save.

Read more about it or order now.

We also have a course for those who want to understand the differences between the 1994 and 2009 ASME standards:
The one-day ASME Y14.5-2009 Update Workshop will teach you about the pertinent changes made to the Y14.5 standard. You’ll learn how the subject matter has been reorganized, and about new sections that have been created for profile, orientation, and form. We offer onsite workshops at your location, public workshops in the Detroit area, and live web workshops that you can access anywhere. Read more about the course.

Q – If a basic dimension does not show a specific tolerance what tolerance should be applied?

Elton Hughes

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A – Basic dimensions by nature are a theoretically exact value; however, the feature(s) of a part they define as ideal or exact do need to have tolerances to permit acceptable levels of imperfection during manufacturing.

When a feature is defined with basic dimensions, the tolerance for that feature must be expressed through a geometric tolerance. Most often, the geometric tolerance is indicated directly to the feature or feature of size on the face of the drawing; however, some companies include a general geometrical tolerance (such as a position tolerance or profile of a surface tolerance) in the drawing’s general notes. This can be an effective tool when the note is carefully written.

Drawings based on ISO standards frequently use a class of general geometrical tolerances standardized in ISO 2768-2 :1989. The three classes are identified through the use of the upper case letters H, K, or L after the ISO 2768 indication on the drawing. You would need a copy of the standard to interpret the amount of tolerance available.

If you are absolutely certain that a geometrical tolerance has not been applied to the basic dimension (check all drawing views), then the drawing must be considered as incomplete. Without a tolerance, selecting a manufacturing process for the considered feature is impossible to do with any amount of certainty, and there is no acceptance criteria to compare measurements to during the inspection process.

Thanks for writing,

Alex

Sales for our new pocket guide are going through the roof!  We’ve extended the  buy 2/get 1 free sale to January 31, 2010, and there’s only one week left. Until Sunday at midnight, if you order 2 pocket guides, you’ll get 1 free.

You can now see a detailed view of the Ultimate GD&t Pocket Guide. We’ve added page views of the information-packed covers, tabbed pages, table of contents, and pages with reference material and GD&T application examples. See the examples here.

Our December web special offers a discount on the Fundamentals of GD&T web-based training course (ASME Y14.5M-1994).

Fundamentals of GD&T Web-Based Training
Register Now

This fully interactive course in geometric dimensioning and tolerancing fundamentals contains 28 lessons that explain the symbols, modifiers, rules, and concepts of GD&T, based on ASME Y14.5M-1994. The course is recommended for all individuals who create or interpret engineering drawings. Topics include:

The pace at ETI has been pretty busy as we continue to develop products and workshops for the new ASME Y14.5-2009 Standard.

We’re nearing completion of the new version of our pocket guide. The GD&T Ultimate Pocket Guide based on ASME Y14.5-2009 will be published in mid-November.

Besides updating it to the 2009 standard, we’ve also added new features to the pocket guide, including:

• A spiral binding that allows the guide to lay flat
• Index tabs on the page edges that provide quick access to topics
• Fold out front and back covers that are packed with reference information
• An additional 50% more information about GD&T topics
• More applications examples to help you envision the concepts
• Cross-references with ASME Y14.5-2009 Standard
• A larger format that provides more room for charts and figures, but still fits in a shirt pocket

The guide will be ready soon, and pre-orders will be taken early next month.

Due to popular demand, we’ve added another 3-hour ASME update seminar to our live web course schedule:

“A Quick Look at the ASME Y14.5-2009 Standard”
Monday, November 2, 2009
1 pm – 4 pm EST
Instructor: Roy Cross

The 3-hour lecture introduces the major changes to the ASME Y14.5-2009 Standard.
It provides insights as to why the changes were made and a short introduction to many of the changes/new features. It also includes a discussion about when it makes sense to implement the new standard.

The seminar price is $70.

Each seminar participant receives:

• Session notes, by Alex Krulikowski
• “Deliberations on Dimensioning and Tolerancing Standards,” Alex Krulikowski’s white paper on developing a strategy for drawing standards
• An ASME Y14.5M-1994 – 2009 Comparison Chart set
• Discount on the one-day ASME Y14.5 1994-2009 Update Workshop

Session notes and comparison chart set will be shipped free within the continental U.S.

Register here

Last month, I blogged about my new geometric tolerancing book that explains the use of ISO standards on technical drawings:

It’s a comprehensive book that can be used to learn the topic, and it’s also a great reference guide. The book is based on ISO 1101-2004 and companion standards.

ETI is offering a course this fall that utilizes the new book. The ISO Geometrical Tolerancing 3-day workshop will be held September 29th – October 1st, here in the Detroit area. The three-day ISO workshop will help you to understand engineering drawings that use the International Standards Organization (ISO) standards.

The course was written with three goals in mind:
1. To help you recognize what is required on a good (standard-compliant) drawing
2. To help you understand geometrical tolerances based on the ISO standards
3. To combine and explain information from dozens of ISO standards into a logical understandable topic

You’ll learn about …

• ISO drawing conventions
• GPS basics
• Limits and fits
• The datum system
• Form controls
• Orientation controls
• Location controls
• Run-out and profile controls
• General tolerances
• Workpiece edges
• Surface texture
• How ISO compares to ASME

If your company is interested in global sourcing and learning how to read drawings created in other countries, this workshop is vital to your success. It will teach you the ins and outs of utilizing the ISO standards and will give you a fundamental knowledge of ISO 1101:2004, related standards, and their application on drawings.

Those who attend the workshop will receive:

• Alex Krulikowski’s ISO Geometrical Tolerancing Reference Guide
• An ISO Geometrical Tolerancing Workbook
• Class handouts
• An official certificate of completion

Read more about the course and specific topics here. I hope to see you in the Detroit area for this exciting new workshop.

The new ASME standard contains numerous changes that affect the specification and interpretation of tolerancing. Companies deciding whether or not to update to the new standard need to understand what has changed and how these changes will impact their product.

As one of the people involved in creating this new version of ASME Y14.5, I have developed a one-day “ASME Y14.5-2009 Update Workshop” that will teach you about the pertinent changes to the standard. This workshop covers over sixty significant revisions, additions, and deletions to the standard. I’ll explain new features and compare them to the 1994 Standard. As part of the course, you’ll receive a set of comprehensive, illustrated charts that highlight itemized changes in the standard.

This drawing shows a small percentage of the changes in the ASME Y14.5 Standard. Click to see the entire drawing.

I’ll explain the major changes to the standard, including:

• Over thirty new or revised terms
• Sixteen new or revised symbols
• Revisions and additions to the fundamental rules
• Revisions and additions to the concept of feature of size
• Revisions and new symbols for datum specifications
• Revisions to composite position tolerances
• Surface boundaries and axis methods of interpretation
• Revisions and new additions to profile tolerances

The ASME Y14.5 1994-2009 Update Course will help you to:

• Understand changes in the standard
• Learn about new symbols and how to apply them to drawings
• Determine the impact of the new standard

ETI can provide this training at your site, and it is also being offered as a public workshop in Michigan on Monday, September 28, 2009. The regular price of this workshop is $375; the first 10 registrants pay only $175.

Attendees must have a basic understanding of Y14.5-1994 Dimensioning and Tolerancing practices.