tired of bad drawings 4

[duk748]

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

 

[JNieman]

Agreed, 100%.

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.

 

[CheckerHater]

@duk748: I am just trying to visualize how bad the drawing actually was.

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

 

[duk748]

hello again & thank you for the replies - the dimensions were like that because they were shown on the drawing like that - jnieman was on the same track as i was - if that drawing were sent out like that to a shop we would look like a bunch of fools & the part would cost an arm & a leg - i believe that a good shop would just reject even looking at the part until it was changed - my biggest concern is how management would even let that drawing go to our in house shop & then not try to show the person who made the drawing how to correct it - now that person will continue to do this same kind of work w/o any real reason to learn or do any better - i am just surprised as to what is allowed to be turned out anymore - dazed & confused

 

[mkcski]

duk748:

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.

 

[monkeydog]

Do you mean there was a dimension as basic and a tolerance?

1.125 +/- .001 BASIC

 

[ctopher]

I have to deal with poor drawing daily. It's because of no training/experience, and don't care/not my problem mentality. It gets worse annually.

Chris, CSWP
SolidWorks '16
ctophers home
SolidWorks Legion

 

[KENAT]

It's not just no training or experience, no one is even setting the expectation and the people doing the work don't seem to take much pride in it (or at least in the quality of the drawings).

However, this (or closely related topics) has been discussed at length before so I'll leave it there.

thread1103-234444
thread1103-265799
thread1103-349546
thread730-221206
thread731-193707
thread732-236588
thread731-232080
thread730-184173
thread732-87322
thread730-282775

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[3DDave]

Shake it off. If no one is noticing there is nothing that can be fixed. The company must have the occasional assembly failure where they talk to the vendor about opening holes up and that is deemed cheaper than getting things done correctly. Best thing to do is to ask for policies at the places you interview.

 

[emorrison]

If your supervisor doesn't see the issue, then take this advice as you see fit but.... you're jousting with a windmill.

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.

 

[mkcski]

KENAT:

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.

 

[MadMango]

Bad drawings come from our own levels of indifference or intolerance. When I started out 30yrs ago I got almost every drawing returned, bled all over with red ink marking the corrections and clarifications I had to make. I hardly see anyone do that today. When you get berated for being too picky, tell them you are only trying to be less ambiguous. I agree with Emorrison, spin it as a cost savings, or whatever manner it needs to be to get upper management support.

"Art without engineering is dreaming; Engineering without art is calculating."

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[KENAT]

mkcksi - the Search Functionality on this site works reasonably well, that's how I did it.

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.

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[mkcski]

MadMango:

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.

 

[mkcski]

KENAT:
Thanks.

 

[natepiercy]

Let's see how this goes.

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

 

[KENAT]

Nate,

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.

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[duk748]

hello again & thanks to all who have chimed in on this subject - i will follow 3ddave's advice & just "shake it off!" - hope all have a great holiday weekend

 

[mkcski]

natepiercy:

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.

 

[CheckerHater]

@natepiercy:

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