【转帖】best way to learn gd

yang686526

best way to learn gd&t???
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?
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.
it helps if you have a good background in plane and solid geometry.   
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

check youtube. there are videos for learning gd&t.
chris
solidworks/pdmworks 08 3.1
autocad 08; catia v5
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   
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
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

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.   
               jhg
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,
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.   
               jhg