tired of bad drawings
tired of bad drawings
(OP)
hello - sorry for a monday mourning rant but here goes - last friday i brought a drawing to the attention of our engineering supervisor that had every dimension on the drawing as basic - datums taken from odd surfaces, incorrect use of true position & tolerances between holes set to .001+/- which are not required - i had suggested to change the drawing to correct the mistakes which were very obvious to someone w/ gd&t training or even good drafting skills - i was told to leave the drawing alone & make no change because the shop would look at the drawing & know to pay a little extra attention when making the part - i was at a loss for words as to why things like this are let go almost regularly & we keep from teaching people in the work force the correct way to do things - i ask how inspection was to check this part & just got a fluff answer w/ a deer in the headlights look - how do people work in engineering for so many years at so many jobs & continue to fly blind & not take responsibility for their work - i had to learn the right way why is it acceptable for some to just get by - now i can have my coffee - have a great week ahead





RE: tired of bad drawings
You'll get three types of responses if a drawing like that goes out for bid.
1- "no bid" from people who could have made the part easily and fairly priced, if the drawing was decent.
2- "low bid" from people who will drag the part out with RFIs and PO change orders to increase the cost to an unreasonable amount, all because of incorrect engineering.
3- Some shop will accept it, just make the widget "good enough" based on their own experience and some gambling, and hope for the best. The part may not even work, and you'll not have much recourse unless you want to burn a bridge and lessen your potential pool of suppliers.
RE: tired of bad drawings
If EVERY dimension on the drawing was basic, how do you know that tolerance between the holes was +/-.001?
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: tired of bad drawings
RE: tired of bad drawings
From my 35 years of exposure to BAD drawings: Mechanical Engrs get NO training in college as to how to communicate their designs. They get a few CAD classes and think they're draftsman - not even close. I found that once exposed to size, form, orientation and location concepts, rookie engineers realize what an important tool GDT is and start to apply it (with constructive critique along the way of course). Those exposed to basic machining and inspection methods understand even more. The root cause: training is the first thing cut from a budget.
RE: tired of bad drawings
1.125 +/- .001 BASIC
RE: tired of bad drawings
Chris, CSWP
SolidWorks '16
ctophers home
SolidWorks Legion
RE: tired of bad drawings
However, this (or closely related topics) has been discussed at length before so I'll leave it there.
thread1103-234444: Degradation of Drawing Standards
thread1103-265799: Drawing Quality
thread1103-349546: Engineers and Crappy Drafting
thread730-221206: I Hate Drawings!!!
thread731-193707: Lazy designers/drafters
thread732-236588: Not getting sucked into CAD
thread731-232080: I am an engineer am I commiting career suicide?
thread730-184173: Are drawings needed anymore?
thread732-87322: Just a CAD drafter
thread730-282775: 2D drawing nearly dead?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: tired of bad drawings
RE: tired of bad drawings
I've had great luck moving smaller companies into better practices WHEN management was on board. Larger companies on the other hand pose a whole different challenge, even with a supervisor on your side.
1. This is the way we've always done it and we've built things that work doing it that way
Probably the biggest corrosive to change, ever.
RE: tired of bad drawings
Might I ask how you filtered past posts to get the list you posted?
And I agree, in addition to the lack of training, mediocrity plays into the "acceptance" (lack of recognition) of BAD drawings. I have also found that the sheer size of a company can impact this because of compartmentalization/departmentalization. In addition, in some cases, the separation of engineering and manufacturing due to outsourcing disallows the consequences of BAD drawings to be recognized for their profit robbing affect.
RE: tired of bad drawings
"Art without engineering is dreaming; Engineering without art is calculating."
Have you read FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies to make the best use of these Forums?
RE: tired of bad drawings
I'm not talking about the fairly generic google custom search at the top of the thread, I'm talking about the 'Search' button on the silver/gray ribbon near the top under the thread title.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: tired of bad drawings
I like the cost savings approach to improvement. But management typically wants to measure the effort to see if savings are realized. This is the tough part as BAD drawings impact many areas.
RE: tired of bad drawings
Thanks.
RE: tired of bad drawings
I'm three years out of college, and I'm sure my drawings aren't what they should be. A lot of what I see here is correct, many schools teach CAD, not engineering communication. I think I had a professor who was the exception to the rule. We did all of the classwork for the lecture portion with pencils and a straightedge. He would assign a 10 point problem and had 15 potential points to take off for errors (e.g. -3 for a dimension to a hidden line, -2 for not extending center lines, -2 for dimensioning to a T, -1 for unbroken crossed witness lines, -1 for calling out a hole in the non-circular view, -1 for missing a center line in right view, -1 if any lines were too thick, -1 for each overall dimension not explicitly given, -1 for any lowercase letters). That said, I like to think I received better instruction than most. Certainly, comparing notes with college friends "up the road" revealed that they were being taught CAD as a main dish, with drawings as a side. I'm pretty comfortable with the way I was taught at my school, but unfortunately our unit on GD&T was only one lecture, which I think (from some extracurricular reading) could have been a whole course in and of itself. To make matters worse, my first job out of college was working in a manufacturing environment where phrases like "don't bother with tolerances - it's a waste of time since our suppliers know how to make our stuff" (that's right, not just GDNT, all tolerances) and "just send them the model and be done with it" were praised by management as a time cost savings. I was scolded once for "wasting" 2 weeks on a drawing with 100+ components.
I'm telling you all this not to get your blood boiling, but to give you some perspective. Speaking on behalf of the last few years' graduates, we're not equipped to make quality drawings right out of the chute. And "entry level jobs" (which, don't forget, all require 2-5 years of experience) aren't willing to invest in anyone and teach them the right way to do things. The result? Exactly what you've been seeing.
I'll be the first to say "yes, I need to know this better" when it comes to drafting rules. Right now I'm working at a very small company where we pursue excellence, and every drawing gets passed around and red-penned before being released. But that can only do so much, since my 2 colleagues have similar background stories. Can anyone recommend a solid textbook or online training course that goes over all the "do"s and "don't"s of drafting? Right now we're in a slow patch, and I know management would be willing to invest in some training to make sure we're putting out quality products. I just need a starting point, and this seems like a group that might know one.
Thanks in advance,
Nate
RE: tired of bad drawings
Asuming in the US not working to ISO then I'd focus directly on the relevant ASME standards Y14.100, especially Y14.5. Not forgetting Y14.3 and Y14.24 among others. If nothing else maybe you management will get you a set.
They don't have everything when it comes to general good drafting practice etc. but most of the truly important stuff is in them somewhere.
If the ranking scheme your instructor uses was really as you give then his priorities seem to be a little off but (while I'm a bit of a pedant, given the general use of CAD with pre-set formatted line styles etc. then spending much time on things like 'line weights' seems questionable, missing dimensions would be more of an issue in typical production environment & I think breaking crossing witness lines may have been dropped some time ago) however it sounds better than what I got.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: tired of bad drawings
RE: tired of bad drawings
I honor your insight at this point in your career. You will go far for sure!
My recommendation:
Purchase all of the Y14.XX series Standards recommended above. All other "books" you can buy are expanded interpretations of what is "required" by these documents.
Drafting concepts - lines types, views, sections, etc - is the "easy" part and repetition will give you competence.
However, what is harder to master is how to communicate the geometric characteristics of features on parts. These are size and form for individual features and orientation and location RELATIONSHIPS between features, which require datums. There are many web sites where you can buy good GD&T materials. Ya gotta read (interpret) before you can write (apply), So. to get the basics for interpretation of GD&T symbols, I recommend getting on the Tec-Ease.com web site and purchasing the "The GD&T Hierarchy" textbook as well as the related workbook and answer books. To move to application concepts, I recommend James D. Meadows' book GD&T "Applications, Analysis and Measurement" as a starting point.
RE: tired of bad drawings
I will add a little to KENAT's and mkcski's advice: have your company pay for "all of the Y14.XX series"
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: tired of bad drawings
RE: tired of bad drawings
Kenat,
That's not a specific example, you're right that things like missing dimensions or lines would be worth more. I just threw together a list of more nitpicky things and threw point values at it to add up to 15 to give an example. If I was to start building a personal library, would 14.100 or 14.5 be the best starting point? Also (admittedly straying quite off topic) as an ASME member, am I eligible for any kind of discount on standards? Or does everyone pay the same price for these?
Mkcski,
Thank you for your recommendations! I just got the thumbs-up to buy the 2009 collection.
RE: tired of bad drawings
There is no "2009 collecdtion" Each standard has its own revision year.
If your drafting skills are not up to snuff, I would get 14.2 first, then 14.3, 14.5. Get 14.41 if you are communication in the electronic 3D-model world and not traditional 2D drawings. Forget 14.100 - very management oriented synopsis. I have heard of the "Genium Drafting Manual", but have never seen it- might be worth investigation.
RE: tired of bad drawings
I'd disagree with mkcski, while 14.100 is fairly high level 'list of standards' for much of its content there are some nuggets in there not covered elsewhere. Especially if you decide to use the non mandatory appendices for guidance - I actually refer to it about as much as any other standard except Y14.5.
Y14.5 is the one I use most but... it is focused on dimensioning & tolerancing and there is more to good drafting than just that.
If your CAD has a canned ASME style setting then you probably won't get much out of Y14.2 so I wouldn't bother with it, and unless you are revising/setting up your templates not sure how much you get out of Y14.1.
For 'general drafting' I'd pick Y14.3 & Y14.24.
If you do castings, forging or molded parts then I'd say Y14.8 is virtually a must.
Y14.34 & Y14.35 also get to be useful on occasion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: tired of bad drawings
I rarely refer to 14.100, but after reading KENATs' comments, he is correct and I agree you should buy 14.100 too.
RE: tired of bad drawings
Its insane.
There was a part that was made to fit inside this assembly. I looked at it and all the dimensions were basic, no criticals or tolerances, AND to top it all off, the dimensions were not taken from the interface surfaces. I brought it up to my boss and said we needed to do an ECN on the drawing because we would have issues, I was told, no no dont worry its fine.
So they had one made and guess what? It didnt fit...
RE: tired of bad drawings
I should have clarified - I was given approval to purchase the Y14.X 2009 collection of "The GD&T Hierarchy" plus workbooks, answer manuals, and pocket ref.
So you both agree that 14.5 is the most useful to start with, if we're only purchasing one at a time? Followed by 14.100, then 14.3? I wasn't kidding when I said "small company" - it's just the three of us. I'm guessing that I'll have more luck asking for smaller packages over a dispersed period of time. We have a weekly meeting and we set aside some time to do knowledge sharing, and I know we will all see the benefit of taking that time to review (or teach) some best practices based on the ASME standards.
RE: tired of bad drawings
I'm a bit dissapointed you jumped to getting the training material etc. rather than the actual standards given what several of us posted but it'll probably work out. The standards by themselves can be a bit dry & in 14.5's case overwhelming.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: tired of bad drawings
In response to KENAT's last post: I agree 14.5 is the DICTIONARY for reading and writing GDT? Ideally you should have 14.5 in front of you and then read the training info and compare the interpretation in the training to the words in the spec.
RE: tired of bad drawings
RE: tired of bad drawings
Over time I would recommend you purchase as much/many training "books" as you can to get different and better examples of GDT applications and their interpretation.
Alex Krulikowskis' materials at ETInews.com are comprehensive. Al Neumann and Bruce Wilson also have web sites, as will as many others. As I mentioned earlier, my personal favorites are Don Days materials at Tec-Ease. The pictorials are really good and in color!
RE: tired of bad drawings
Step 1) Person is introduced to the concepts.
Step 2) Some examples are seen. (seeing the basic (pun!) symbols)
Step 3) Person tries simple program that is evaluated by non-biased computer/software. (understanding the grammar)
Step 4) Repeat 3 until program meets expectations. (understanding basic tolerance analysis)
Step 5) Practice increasingly complex programs evaluated by non-biased computer/software.
Step 6) Repeat 5 until programs meet expectations. (understanding medium tolerance analysis)
Step 7) Learn to analyze software written by others (understanding complex tolerance analysis)
Step 8) Learn to generate programs that write other programs (creating tolerance schemes to match variation limit requirements)
What is usually missing is everything at step 3 and after. The only non-biased computer I've come across for dealing with D&T was the software from VSA. It was easily checked to see that its analysis conformed to Y14.5 and produced results that should be expected from the dimensioning and tolerancing scheme applied by a compliant factory.
For most people it's like learning to program by asking other people what they think a program will do when none of them has had access to a computer. While it's possible to do, the rate of success is going to be low and the rate of people believing their own incorrect answers is high. The lack of a standard, unbiased method of evaluation continues to be a problem with people creating and sticking to incorrect and sometimes outlandish interpretations.
Most training materials are stuck at step 2. If there is low-cost, easy-to-use software that clearly demonstrates the effects of tolerance schemes it would be good to know. VSA and Sigmetrix aren't in that category, however good they are.
RE: tired of bad drawings
I agree that "talking heads" in GDT videos are boring and do not provide motivation to understand concepts. I was very fortunate to have a mentor at my place of work in the 1980's. He was a great teacher. After I caught up to his level, we both advanced our understanding by attending seminars presented by Y14.5 committee members at our place of work and at "engineering" conventions. We continually picked the brains of these "experts" via fax and later email.
Natepiercy: Given my experiences, I highly recommend you find a mentor and attend seminars presented by a real person! Plus using this Forum as a springboard !!!
RE: tired of bad drawings
RE: tired of bad drawings
Get on the ASME web site and look for GDT "classes" sponsored by ASME. The ones I attended in the 80' and 90's were at ASME conventions held throughout the year (so members can present papers and vendors can show their wares).
I am currently signed up to attend a "stacks" seminar at Effective Training Inc (ETI)in Lavonia, MI ETI is a SAE division. They have many classes available.
Tec-Ease also has classes. I attended a "what's new in 2009" seminar run by Don Day at a Y14 committee meeting in 2010. He is very dynamic but I am not sure he is still presenting.
At great cost, you can pay an "exert" to come to your office/plant. The company I work at in the 80's had Al Neumann come for a whole week and run 2 sessions each day. I learned and unlearned quite a bit.
RE: tired of bad drawings
The underlying problem isn't the difficulty of learning the material, it's that those who don't care to learn it have an opinion and do care to share it. Hence the need for a non-person evaluation.
D&T has been around for more than half a century, but it is generally poorly used because of the pulled-from-the-... analytical ability of the 95% who think they know something because they got to what I numbered as stage 2. I doubt that anyone would hire a programmer with the same stage 2 credentials (though I've read enough Daily WTF to know that doesn't stop idiots with opinions commenting on software; not the commenters on DWTF who are hilarious, the people they work with/for.)
RE: tired of bad drawings
Thanks for the update on Don Day. I was following his blog on and off for years and all of a sudden it ended. Now I know why. This is a great loss for him family, friends, the GDT community and to advancement of the "technology".
I totally agree with your comment "those who don't care to learn it have an opinion and do care to share". I have run into many "expert" students in my intro class who argue the definitions even after I read them word for word. They refuse to believe they have been doing it wrong - incorrectly inspecting flatness (as parallelism) is a classic - and that they need to unlearn some things. Oh well.
My problem for many years was the lack of an "official" test to give some creditably to those who do know GDT. Finally in the 1990s the test arrived. I was somewhat disappointed after taking the test (in 1999) that it mainly required one to regurgitate the standard and there were too few "analysis/calculation" type of questions. Anyway, from my travels, testing in this subject is one of the hardest things to do fairly.