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Best way to learn GD&T??? 1

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pacific123

pacific123

Aerospace
Mar 6, 2009
20
0
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US
Hi guys,

I'm a little baffled as to why GD&T is not taught in schools and Universities in the US. I mean they talk about it for a little bit but they have no dedicated GD&T courses that run the whole semester. If GD&T is such a necessity (which I believe), why doesn't ASME step in and "force" colleges to teach GD&T? I fail to understand how one can be officially recognized by ASME as an Engineer, but yet knows very little about GD&T.

That being said. What is the best way to learn GD&T??
I have bought books that are great, but it is so complex that it becomes hard to understand some concepts. Then I checked out some DVD course but they charge $850 per DVD????

Any thoughts?
 
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Pacific123:

GD&T is not taught that well in Canada either. There are some community colleges here that offer evening courses but the teachers may not be qualified and I don't think they could answer some tough GD&T questions.

I would suggest that you take a basic 2 day course from one of the companies that specialize in the subject where the trainer is a GD&T Professional. At least any certification would be traceable to ASME. After the initial course, apply it for a while and then look for a more advanced course.

Here is the tough part though. As you may see by some of the responses here, simple answers turn complicated. I know that there are at least a couple of contributors in this forum who may pose answers that I just can't figure out what they are attempted to say. So, the trainer must be able to communicate in simple language that we all understand.

You may also look into live online seminars which are not quite accepted yet but will be in the future.

Lastly, I would suggest that you keep coming back to this forum with either a question or just reviewing questions and answers. One can learn a great deal about GD&T here.

Hope this helps.

Dave D.
 
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Pacific123,

I agree that it is true enough that GD&T can seem quite complicated and it well may rack your brain once a not so straight forward or unusual callout(s) are required. Add a few opinions from others in there and wha lah... a migraine! However an experienced GDT designer or engineer can be invaluable as a mentor. There are allot of concepts to learn and comprehend that require mental images developed from word definitions. I think this is the first obstacle to overcome. It helps to learn the understand the concepts, definitions and rules while being able to visualize relative to a parts. I have had a number of GDT classes starting with the 1973 standard and then the 1982 and 1994 versions. As eluded to above some pre-requisites would be helpful before a class. Ringster mentions plane and solid geometry. I think for me things starting "clicking" once I had some true "design" ownership experience. Understanding how parts are manufactured, inspected and assembled. I have had very dry instructors and then more teacher oriented classes also. I mean people who teach this stuff who have had a variety of industry experience with design ownership. “Teachers” can develop interest and can describe applications in more than one way, not just present material from a book. I would say to shop around for an instructor that is or has been involved in industry not just a classroom. Finally I would say that a 2 day course probably isn’t enough even for the basics. I have mentored many many young engineers exposed to the basics in less than 20hrs. From my experience a minimum 40 hour course taken over a 2 week period provides some time for this material to start "sinking in". This website is a very good place to develop questions to ask prior to taking a course. Get your money’s worth; ask questions!


DesignBiz

 
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I would actually discourage too much too soon based on what I've seen at my place. They had a week GD&T training for most engineers from a member (maybe ex member) of the ASME Y14.5M committee just before I started here. Very few of the engineers, including some that had previous experience of GD&T, have shown any great talent or ability for using it, even for simple hole patterns and the like. In fact despite the training some argue strongly against it.

I haven't had any formal training but did work through the notes from the training, worked with an experienced checker for a while and have often looked up things in the standard, on this site etc. Without being arrogant I think it's fair to say I'm probably better than any of the other permanent staff here (the experienced guy was laid off some time).

I also have an intern right now who's only training was a self paced online course, which I'm not even sure he completed, and a couple of lessons at school. He has shown more ability and skill in his use of GD&T than any other permanent employee.

So I'd say the biggest factor is actually the person learning the GD&T, far more so than the training itself. If they are motivated to do it they'll make the best of whatever training & other resources they are provided with. If they aren't motivated then the best training won't improve them much.

I have a senior checker here on contract who actually gives a short training course (or has at previous employers in aerospace). I think he introduces the symbols/meanings and gets them up to speed on simple hole patterns or something to that effect. This probably covers 75% or more of the GD&T that gets used here.

Beyond that, unless you have big intentions of becoming a GD&T expert then working alongside experienced practitioners is from my experience a good way.

I would like formal training but it’s not on the cards anytime soon.

DesignBiz is definitely right about the sinking in part though.


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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Two days is TOO intense. Three is bearable, but students' heads are foggy by the end even then. Repetition is the key. I've heard that the average person is lucky to absorb about 60% of what they experience in any course, and that it drops off after about 6 weeks. Repetition reinforces and builds on what is retained. Exposure to different trainers & training materials is also beneficial. And no, not all trainers or materials are created equal.

Unfortunately, this lack of GD&T education in school is just symptomatic of North America's (Canada & USA & Mexico) failure to provide practical technical skills. Don't get me wrong, universities must teach the theories because that is the level where it is appropriate. They need to throw in some design training and practical experience too. Of course, this is also true of manufacturing (machists vs button pushers), inspectors (open setup vs contact CMM operation)... the list goes on.

Jim Sykes, P.Eng, GDTP-S
Profile Services TecEase, Inc.
 
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What's the best way to teach GD&T?

As I see it, here's a similar question...what's the best way to teach a 16 yr old to become a responsible adult?

I've seen dimensional engineers working in the field for more than 5 years...supposed tolerance analysis experts...NOT be able to identify the functional datums of a part correctly...or place callouts on drawings that have no chance to repeat based on any current measurement system technology.

The problem? We have a lot of people who have taken those 2 day to 1 week courses...and do not have a mentor available. Management believes its enough...so they are creating and releasing drawings....And...well...we laid off our checkers too.

By the way...did you get the memo that drawing quality needs to improve?

I think GD&T is learned by a relationship between student and mentor...kind of like a teenager and adult role model.

I think it starts to sink in when the student sees what a callout means in terms of the CMM, the secondary tooling, the function...something other than the symbols on the paper.

I can take a design release engineer who knows what he knows and admits what he doesn't know...and teach him GD&T reasonably well. This involves time going through his design with him...attending meetings with suppliers...etc...
I've done this. After at least a few hours a week for several months the designers GD&T skills show remarkable improvement...and I don't have to change his drawings as much.

The biggest problem??? Just like the parent/teenager thing...when the student is not ready to listen to the teacher. Adults know that teenagers understand things in an immature sense...But it takes a while before the teenager can understand that.

My thought is that GD&T instruction should be treated more like the apprenticeships they use in skilled trades. Until then, the number of drawings that have major errors will probably rise...I've seen estimates that right now its about 50%.

IMO...real GD&T training is not done by a method of instant gratification.

Michael
GDTP-S0470
 
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pacific123,

Buy a copy of ASME Y14.5M-1994.

This is the standard. This is the reference everybody works from. It is officially correct, and it is quite readable.

Critter.gif
JHG
 
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drawoh, that's pretty much the approach I've taken the last 18 months or so and to some extent before.

However, when you're first getting up to speed I think some extra material or training is highly beneficial.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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KENAT,

I agree with you on the training. I am not so sure about the literature. I have seen a number of Eng-Tips posts describing things in the textbooks that to me, do not make sense.

Do the really serious gurus around here have recommendations about GD&T literature? All I have here is the standard, and my GD&T course notes.

Critter.gif
JHG
 
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Drawoh, in my case the 'material' I was thinking of is the course notes from the GD&t training provided by a memeber of the ASME commitee shortly before I joined this company.

I agree that I've seen either directly or second hand things on other texts or even some of the websites that don't match my understanding of 14.5.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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Guys,
Thanks for all your responses.
It seems to me that because it does take so long to sink in, it should be taught in Universities during the course of our 4-year degree. So the first year, you would go over basic blueprint and some basic GD&T, and years 2,3 & 4 you would go more and more in-depth into GD&T concepts and applications.

Oh well, I guess we won't be re-writing their curriculum today... kinda sad to leave it up to the students to tackle that big of a subject on their own.
 
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pacific.

Couple of thoughts -

For it to really 'sink in' they'd have to do so many hours of assignments, that in turn would have to be graded that I'm not sure it's realistic. 8hrs+ per week in addition to class time for 4 years sounds quite a bit to me. Plus canned assignments still may not expose them to everything etc. so I think there are limits to the competency that can really be achieve in a purely academic setting. I really think you end up learning more from the application than more formal teaching.

That said, I think they definitely could, and probably should, do better.

Second, many engineers view detail drafting/designing as, if not below them, then at least not their 'core competency'. Just look at any of the many threads about this. At best you could try and convince them they need to know enough to be able to understand what designers are doing before they approve it.

There are still places which have the division of labor between drafting and hardcore engineering, in fact we're talking about re-introducing it to some extent at my current place.

ASME does have a committee looking at gaps between what students are taught and what industry expects of new grads. A former colleague was on this committee as I recall. One area they were looking at was GD&T.


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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Are they going to bring back the formal checker?

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]
 
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ewh, you asking about my place? Well one scenario does see them getting a checker to work with some drafters. The odd thing is that they'll be reporting to manufacturing not engineering - go figure.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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Who will be reporting to manufacturing, the checker or the drafters or both? Either way, I don't think it improves the situation much from a design perspective. Things should be easier to manufacture, though! ;-)

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]
 
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Both. I predict the intent is that Engineering come up with a working prototype (little regard to ease of manufacture, tolerancing etc.) and then throw it over the wall to manufacturing to do the rest.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
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