Drawing Quality 4

[drawoh]

This is a question for fabricators, inspectors and manufacturers. thread1103-265767 is drifting off topic, so I am starting this thread.

How good are the drawings you are being sent? Do they make sense as per drafting standards? Are you willing to promise to meet the dimensions and tolerances?

JHG

 

[fsincox]

Thanks Ken
The checkers I worked with then, did not know any standards but "company standards". They had no interest in national standards any more than if they were ISO standards. Now I work in areospace and I see a nominal interest by management in at least looking like we adhere to standards because the apperance of it is good for buisness so I do see the difference.
Frank

 

[fsincox]

Ken,
I am reading your thread 1103-192933 on GD&T parts costing more. Powerhound’s comments about bad GD&T stand out in particular as he references his perspective. That and many other threads here indicate to me from the outside world that you were very lucky to have a good friend/mentor. I did too, he was a checker also, Art.
Frank

 

[Daekar]

I can speak for two US manufacturing companies, and say without any reservation whatsoever that 99% of the people I work with, even the ones that produce drawings, don't know how much of the drawing standard works. I even had a senior engineer try and tell me that basic dimensions aren't required for true position tolerances! Even though our prints go through three people (drafter, design engineer, manufacturing engineer) who are supposed to check them for problems before they reach us, we find issues constantly. The more I learn about the standard, the more I believe that the number of prints I've seen that comply to it completely could be counted on my fingers and toes without taking off my shoes. As for visual quality, it varies widely. Sometimes we can barely read prints, particulary if they're for an ECO, and sometimes they're high resolution and extremely easy to read. I believe several posters hit things on the head: People don't know the standard, don't want to know the standard, and the companies don't care - or at least, not until they get some bad parts because the drawings were garbage, at which point nothing happens except they mark up the print on the floor and remake or rework the bad parts. CAD has helped for high-complexity parts, I think, but where I work there are several CAD packages being used in parallel, many older engineers who don't want to learn 3D drafting (let alone GD&T and the drawing standard), and lots of young engineers fresh out of Virginia Tech who learned CAD modelling upside-down and backwards at school but nothing about actually producing drawings (Yes, I've asked them and they stated unashamedly that they learned nothing about dimensioning and tolerancing).

 

[fsincox]

I mentioned here before a story: I was in an argument with our lead of quality, the nominal head of our GD&T effort, he claimed that you allways know how to layout parts in inspection because; "A is primary, B is sec....., etc". I asked him why do they bother to reference datums in the DRF then if it is always the same and you are going to ignore that part of the frame. I think he quickly got the point.
Frank

 

[dgallup]

I took a drafting course in college before there was any CAD software. They did not teach a word about dimensioning and tolerancing then either. Technical schools may have taught it but not my 4 year engineering school. I absolutely hated board drawing and for the first decade of my career we had draftsmen working on boards. I did take GD&T courses and studied drafting standards as part of my work experience. I would not be doing what I do today if parametric solid modeling CAD had not come along and displaced all those asleep at the board drafters.