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 – 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

A few years ago, I decided to put together some type of graphic that would organize and illustrate the many levels of workshops that ETI offers. It needed to include the prerequisites for each course and some way to easily visualize the entire  GD&T training hierarchy. The GD&T Training Pyramid was the result. (Click on the graphic above to access a larger view.)

The pyramid allows you to see all the training levels, as well as the basic courses – or the foundation – upon which your GD&T education should build. We often find that students attempt to master a higher level course without fully understanding the basics. For example, if you don’t completely understand the requirements of engineering drawings, you won’t be ready to learn GD&T fundamentals.

The pyramid also incorporates the valuable concept of mentoring employees. Once a workshop is over, mentoring allows employees to utilize their newly attained GD&T knowledge to its full potential on the job. The gray areas in the pyramid signify those areas where I advise that the mentoring be implemented.

In these tough economic times, companies often cut training budgets first, but allowing ETI to assist them in incorporating a mentoring program into the workplace can often mean valuable dollars are saved through the best use of manpower and materials.

In future blogs, I’ll go into more detail about each of the pyramid’s levels. If you’d like your own copy of the GD&T Training Pyramid, click 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.

I am working on a new geometric tolerancing book that explains the use of ISO standards on technical drawings. This comprehensive book can be used for multiple purposes: the topics are organized in a format conducive to learning the topic, plus it contains many features that make it a great reference guide. The book is based on ISO 1101-2004 and companion standards.

This is an exciting project, and I’m anxious to complete the final draft. The book is very close to the expert review stage. The process of having a team of technical experts proofread a new book is an important part of writing a technically sound book. I have learned from previous projects that it always results in a better product.

I have most of the proofreading team in place, but I would like to have three or four additional technical experts who are experienced in ISO GPS. Proofreading requires a commitment of your time. I am estimating the draft will be ready for review by mid to late June, and the technical review must be completed by about 30 days after that.

There is no pay for proofreading, but there are rewards. First, you will enjoy reading and dissecting each section of the book. You may even find some new information on some aspect of the ISO standards. Also, your name will be listed in the credits, and you will receive a free copy of the book when it is published.

If you are experienced in ISO GPS standards and would like to be part of the proofreading team, send me an email describing your expertise level, and I’ll add your name to the list of prospective technical experts for proofreading.

Sincere thanks,

Alex

We’ve been pretty busy this spring, preparing courses, books, workbooks, and charts to keep pace with the new ASME Y14.5-2009 Standard.

Aside from that focus, we also finished developing our latest web-based training course on engineering drawing requirements. The course contains four lessons that cover:

• The definition and uses of engineering drawings
• Types of engineering drawings
• Appropriate standards and documents specified on engineering drawings
• Basic part definition required on engineering drawings

The web-based course is geared to people who work with and interpret engineering drawings. It’s based on Y14.100-2004 and Y14.24-1999 standards, takes about 4-6 hours to complete and can be purchased for 30-, 60-, or 90-day access. It includes practice problems, quizzes, and a drawing packet containing 12 engineering drawings in printable PDF format.

With many companies undergoing budget cuts, this online workshop is perfect for those who need training but can’t travel to our public workshops. You can read more about the course and the complete list of drawings that are covered at our ETI Learning Center website.

We also have a tutorial that you can view to get a preview of the course. View the tutorial.

An article on the reliableplant.com website about the current economic issues in industry caught my attention. The title says it all: “Economics Drive Need for Change [in] Management Expertise and Outcome.”

In the article, ESI International revealed the top 10 project management trends that will impact both private and public sector organizations this year.

Two of the trends listed were:

1. People Will Come Before Technology
   Organizations will increase their demands for smart third-party guidance that ensures technology investments deliver enhanced performance. This will result in greater recognition of the critical role people play, leading to increased recognition that employees need the right skills and knowledge before applying processes for consistency and adding technology to deliver increased efficiencies.
2. Right-sizing Staff with Demand Driven Resource Management
   The adoption of demand-driven resource management will increase significantly in 2009. Its ability to right-size internal staff and draw on outside contractors when demand requires will be viewed as an essential cost containment approach leading to greater organizational performance and efficiency.

The first point mentions the importance of employees having the “right skills and knowledge before applying processes.” In this economic slowdown, some companies are wisely taking advantage of more time to train their employees, and ETI is meeting those needs with our excellent GD&T training options.

However, many companies are also striving to finish products quickly, and their workforces may be overloaded. As the second point mentions, they may need to “draw on outside contractors when demand requires.”

ETI Adding Engineering Services
In line with meeting our customer needs, we now are offering engineering services. Our engineering services include design checking, adding GD&T to customer designs, and tolerance analysis. These services are competitively priced and will be performed by industry experts. Call our sales team for a quote on your specific need, or request a quote online.

Link to article: http://www.reliableplant.com/Article.aspx?articleid=15207

American culture’s impatience with time…

Charging into building the product, without sufficient thought into the design, results in a product built to many incorrect assumptions. These assumptions remain unidentified until very late and are costly to fix.

Joshua Hammond and James Morrison

A gem from “The Stuff Americans are Made Of.”

Most drawings that I see require assumptions to interpret. We could make great strides in quality if we just made “technically correct drawings.”

Quality really begins with the drawing.

It’s literally been years in the making…we started developing this workbook more than 5 years ago, but other projects got in the way. Computer-based training, web-based training, developing new courses like the Engineering Drawing Requirements, the System Approach to Component Tolerancing, and lots of other products and services always seemed to take precedence over our new workbook.

We kept plugging away, and we can finally offer this valuable tool for practicing GD&T concepts. The official title is The GD&T Workbook With Engineering Drawings, by Alex Krulikowski. It’s a companion to the Fundamentals of GD&T textbook and will be part of all ETI’s fundamentals workshops.

The content matches that of the textbook and also fits pretty seamlessly with the GD&T Trainer, so anyone using the our CBT or web-based training might want to use this for extra practice. I recommend working the exercises after you’ve completed a lesson, but before you try the quiz.

Seeing the GD&T concepts you’ve just learned applied to an actual part drawing is a great way to get hands-on practice. Anyone who already knows GD&T can also use this for review and practice.

The workbook is available in our online product catalog.