Known as the "Doctor of Dimensioning," Alex Krulikowski is a noted educator, author, and expert on Geometric Dimensioning and Tolerancing (GD&T). He has more than 30 years of industrial experience putting GD&T to practical use on the shop floor.
Alex has taught GD&T
to tens of thousands through his workshops and seminars, and to countless
others through his books, self-study courses, videos, and computer-based
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geometric tolerances in stacks.
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We are what we repeatedly do. Excellence, then, is not an act but a habit.
is a regular online publication devoted to Geometric Dimensioning &
Tolerancing. Each edition features a host of GD&T resources and links,
as well as dimensioning tips by noted GD&T author and ETI founder,
Alex Krulikowski. We also invite you to visit our website, etinews.com.
To view past issues of ETImail, see the archives.
Many significant events took place in 1985. Desktop publishing began. The first laser printers went on the market. The first British mobile phone company was incorporated. Microsoft started the first version of Windows. The Internet Domain Names System was initiated.
Most of these technological changes have had a significant impact on our daily lives. Can you imagine life without a cell phone? Do you remember a time before companies had domain names and websites? Thousands of Windows-based computer programs have allowed us to do everything from calculate our own taxes to create spreadsheets, databases, and documents easily at home and work.
Who can imagine going back to the time before Microsoft Windows, desktop publishing, and laser printers? Typing documents on manual typewriters (and retyping when changes occur), or paying printing companies to do layout and design for small company newsletters is a thing of the past. Printing our own documents within minutes at home or work is so commonplace that we hardly remember a time when we didn't. Having access to affordable desktop publishing programs and personal laser printers has greatly simplified our lives.
Another important event occurred twenty years ago. In 1985, I began a small start up company that provided training and consulting in a little-known discipline called geometric dimensioning and tolerancing. One year later, I developed a GD&T self-study course. Twenty years later, Effective Training Inc. has evolved into a corporation that provides GD&T training, products and services to organizations across the globe.
Just as the cell phone, Windows, and other computer technologies have affected and improved our lives, using GD&T on engineering drawings has made a significant impact on how companies communicate their design requirements. Over the years, geometric tolerancing has saved organizations valuable time and money in the manufacturing stage. In fact, GD&T is now used by tens of thousands of manufacturers world-wide. That's quite a change from twenty years ago.
In 1985, I recognized what a valuable tool geometric dimensioning and tolerancing is. I have spent the past 20 years of my life extolling its virtues and trying to help others understand the significance that the language of GD&T can have on any company's design process. For two decades, I have developed courses, books, software, and other training resources to help others learn how to correctly utlilize GD&T. I have spent years of my life teaching hands-on workshops to thousands of students who want to learn how to apply and interpret GD&T correctly. I understood twenty years ago that geometric dimensioning and tolerancing was a technological advancement that vastly improves design quality and production, and I have devoted my life to sharing this knowledge with others.
Since 1985, there have been significant improvements in the topic of GD&T, the technology I use to teach GD&T, the tools companies use to apply GD&T, and the role of GD&T in industry. The GD&T standards have evolved to be more complete and to accommodate electronic gauging and the use of solid models. Several new or updated standards are available to industry: the Y14.5 standard had a major update in 1994, a new standard on tolerancing of solid models (Y14.41) and a gauging standard (Y14.43) were both published in 2003. These standards filled in many of the gaps that industry was struggling with. The use of ISO standards is also increasing in the United States.
Dimensioning and tolerancing standards will continue evolve to meet the changes in industry. My start-up product, the self-study workbook has evolved into video training, computer-based training programs, and web-based GD&T training. Industry has implemented several new tools that use GD&T to work properly. CAD programs use GD&T, and some can even embed GD&T with the model features. Digital drawings have become mainstream in industry. Several programs are available to interpret and inspect GD&T from the solid model. A number of tolerance analysis programs are available that include the use of GD&T in the software.
In 20 years, I've been asked quite a few questions about GD&T usage and details. In this issue and the next, I'll reveal the top 10 questions about GD&T and their answers. I hope you find them helpful.
Top 10 GD&T Questions, part 1:
1. I have a fundamental question. What kind of control would one have on say, a machined circular part with a thru hole and a counterbored hole midway thru the part? Size dimensions are not important, but we are not using any positional tolerancing, just plain sizes given for the different diameters and counterbore hole depth. If there are no location controls given, does that mean that the thru hole can be anywhere on the cylindrical part? Thank you, KW
I am employed with a large company and am a
recent student of Advanced Concepts of GD&T taught using your textbook,
but by a GD&T instructor who is not from Effective Training.
3. We design and develop one-of-a-kind experiments to be used on the International Space Station. As such, the parts we make are one of a kind. At best, we make two copies of the same part. Our designers have a minimal knowledge of GD&T. For the work we do (one of a kind) does it make sense to spend the time and money to educate our designers on GD&T?
Some people within our organization say for one-of-a-kind projects, GD&T is overkill and a waste of time. What argues in favor of GD&T for these drawings? I am a proponent of GD&T and know the cost savings available over time in production situations. I also know the cost savings available if a designer is sufficiently knowledgeable about GD&T to use it as a design tool.
Educating our designers in GD&T will take years. In the end, it will be worth it, but today people say it's not worth the schedule slip (i.e. its more trouble than its worth) for one-of-a-kind items. I can't come up with a good argument to refute the short term schedule, one-of-a-kind arguments. Any suggestions?? Thanks, Joe
4. Under ASME Y14.5M-1994, are metric dimensions quoted with a digit preceding the decimal, whereas English dimensions are not? (For example, a metric dimension might read 0.01 and an English dimension would read .0004) If so, where would this be stated in the ASME document? Thank You, Jim
5. I would like information on "simultaneous requirement default." Is this subject covered in Y14.5 or in any of your materials?
Figure 1 shows the part you described. You asked “If there are no location controls given, does that mean that the thru hole can be anywhere on the cylindrical part?” That is correct. With this drawing, there is no specification on how much the hole and counter can be offset from each other, or in relation to the outside diameter. The drawing is incomplete. The supplier could produce a part that had any amount of offset between the diameters and it would pass the vague print specifications.
Depending on how the part functions, position control or runout controls could be used to complete the part definition. One possible solution to completing the part tolerancing is shown in Figure 2.
I would like to point out the additional controls do not add cost; they complete the part definition. The amount of tolerance that is specified in the geometric tolerances is what determines the costs involved.
Answer to Question 2
There may be other circumstances that could influence the situation. If you send or FAX the drawing to me, I will provide you with a more certain answer.
The problem you describe is fairly common. I feel your pain. It is very difficult to get people to step out of their comfort zone and let go of old habits.
However, the short answer is yes, it does make sense to spend time training. I have a few suggestions for you to consider when discussing if GD&T is appropriate for low volume parts (or even one or two part runs). Here is a list of the top twenty-one reasons why GD&T should be used on low volume products. I hope this information helps.
The proper use of GD&T will enable you to. . .
Download and print a free "Top 21 Reasons to Use GD&T" chart. ETI would like you to have a free copy of our "Top 21 Reasons to Use GD&T" chart. The printable chart is 11" x 17" and in pdf format. For a free copy of the chart, click here.
For metric unit dimensions, Y14.5M-1994 paragraph 1.6.1(a) Millimeter Dimensioning states, “Where the dimension is less than one millimeter, a zero precedes the decimal point." For English unit dimensions, Y14.5M-1994 paragraph 1.6.2(a) Decimal Inch Dimensioning states “a zero is not used before the decimal point for values less than one inch."
The simultaneous requirement concept is often misunderstood. It is a default condition on many drawings, so drawing users don't find any modifiers, notes, or symbols to remind them when simultaneous requirements must be used. It is important because, in some cases, it allows additional tolerance that must be comprehended in inspection and engineering analysis.
The concept of simultaneous or separate requirements affects the part in two cases: when the datum references are size datum features and when the angular relationship between patterns are involved. When the simultaneous requirement is used, it eliminates tolerance between the toleranced patterns. When the separate requirement is invoked, it allows additional tolerance between the toleranced patterns.
This article provides a brief explanation of the concepts involved with simultaneous and separate requirements. A more in-depth discussion of simultaneous and separate requirements is provided in my book, Advanced Concepts of GD&T. The “simultaneous requirement default” is covered in sections 22.214.171.124 and 126.96.36.199 in Y14.5. The sections are shown below.
In this paragraph, the standard defines the conditions for when the simultaneous requirement default apply. In this case, the specifications are at RFS. Figure 5-16 shows a drawing where the conditions are met for a simultaneous requirement.
Alex’s comments: When RFS or planar datums are involved, it doesn’t matter if the features are treated as a simultaneous or separate requirement, the results will be the same.
In this paragraph, the standard defines the conditions for when the simultaneous requirement default apply in MMC applications. Figure 5-18 shows a drawing where the simultaneous requirement has been overridden by the SEPT REQT notation.
Alex’s comments: In MMC applications, with size datum features, if a separate requirement is involved a datum shift between the patterns is available.
There you have it...five of the top ten most frequently asked questions that I've received in 20 years as a GD&T instructor and consultant. Look for five more in the next issue of ETImail, and, as always, I welcome your questions or comments.
Standards in the News takes a look at real-life issues involving standards.
This month: failure to meet its own company standards creates costly problems
Excerpt from the interfax.cn website
SONY WILL REFUND CHINESE CONSUMERS WHO BOUGHT DIGITAL CAMERAS THAT FAILED INSPECTION
This issue of Standards in the News features an article from Interfax about a costly problem for Sony when its digital cameras failed to meet the company's own standards.
Shanghai. December 19. INTERFAX-CHINA - Sony will allow Chinese consumers that bought one of six Sony digital camera models that failed a quality inspection to return their cameras for a refund, the Japanese electronics giant said Sunday.
The Zhejiang Administration for Industry and Commerce announced last week that six Sony digital cameras had failed a quality inspection, and ordered a ban on sales of the cameras in eastern China's Zhejiang Province. Sony announced Friday that it would stop sales of the six digital cameras nationwide.
Because China does not yet have national standards for digital camera products, the Zhejiang Administration for Industry and Commerce carried out its inspections using standards provided by Sony, as well as recommended industrial standards. Two of Sony's digital cameras failed to meet the company's own standards, while four failed to meet recommended industrial standards for digital cameras.
"We agreed with the inspection results," Kang Jian, a PR official with Sony (China), told Interfax. "But part of the reason for the failure to meet standards was that we submitted the wrong enterprise standards for use in the inspections."
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ETI continues to add new GD&T products and services and provide you with more GD&T training options. Keep an eye on this section to read about our latest news. This month: ETI brings hands-on GD&T workshops to a city near you.
Workshops Available Throughout the U.S.
ETI's public workshops are complete courses that teach how to apply and interpret GD&T on the job. They are more in depth than most public seminars, and much more than simply lectures. Each workshop provides hands-on training that includes practice exercises to help reinforce concepts. When you register for any ETI workshop, you know you'll be receiving the most thorough GD&T training available.
All workshops include:
The cost for our 2-day workshops is only $595, and includes software and resources worth over $350. Each person who attends a 2-day workshop receives:
The cost for our 1-day workshops is only $345, and includes software and resources worth over $50. Each person who attends a 1-day workshop receives:
The workshop schedule for the first half of 2006 brings training to:
ETI offers a variety of discounts on our public workshops:
Would you like ETI to bring GD&T training to an area near you? Suggest a workshop location.
Students who attend our workshops walk away with more than knowledge. They gain on-the-job skills because our materials are performance-based, and each workshop approaches the subject from a design perspective.
We would appreciate it if you'd keep us in mind when you need GD&T training, consulting, or GD&T products. Feel free to contact us by email or by phone at 734-728-0909 or 800-886-0909.
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