Degradation of Drawing Standards 13

[chancey]

Ok I am not old old school because I didn’t start on the board but has anyone else noticed the degradation of drawing standards? I think this really boils down to the use of CAD. Now that most packages have become easier to use (unlike the early versions of Pro E & MDT) I think more people are creating drawings. Things I see a lot of are missing hidden lines (I understand clarity reasons), lack of centerlines, dimensioning with disregard to intent (like not coming from datums), lack of tolerance consideration (like 3place decimals throughout), dimensioning to hidden lines, poor overall dimensioning & view layout, over crowding, etc. And god forbid they try to use GD & T.

I must just be getting older and grumpier…

 

[spongebob007]

Another problem is that management types routinely confuse the term "CAD operator" with "draftsman" or "designer".

I have worked with a couple of these folks whose only qualification is that they took a Pro/E training class. They have no background in the fundamentals whatsoever.

 

[ctopher]

A lot of management types don't know what "CAD" is.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[spongebob007]

True story:

At my first job out of college (1994) I worked with this woman who held a college degree in interior design. She had trouble finding work in her field, so she took a CAD training class and ended up getting hired as a mechanical drafter.

 

[ewh]

At least she wasn't hired as a designer or engineer ;-)

"The ambassador and the general were briefing me on the - the vast majority of Iraqis want to live in a peaceful, free world. And we will find these people and we will bring them to justice." - [small]George Bush, Washington DC, 27 October, 2003[/small]

 

[ctopher]

At my last company we lost our checker. Our manager liked the girl working in the copy room, so she became our checker.
For several years we argued and fought. She eventually quit, then he followed. Both were married to others, but rumors flew about the two of them.
Drawings errors were high during her time as 'checker'.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[KENAT]

So Chris, does that mean I'm not the least qualified checker ever;-)

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[ctopher]

You're not even close, compared to what I have experienced.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[chancey]

The two lead desingers I work with actually have the best GD & T knowledge in my company and are more than familiar with the standards. And I realize some engineers/designers think they are above drafting but wouldn't you want to make sure that some drafter didn't just kill your design on the drawing? Because if it fails guess where everyones pointing their fingers.

 

[KENAT]

Chancey, that's another part of my reasoning for why it's not a bad idea for Engineers to have reasonable familiariy with drafting skills. Even if they're fortunate enough to have someone else preparing their prints shouldn't they know enough to recognize major errors - especially if it's in part of industry where they have to stamp it.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[CheckerRon]

I see that Chancey had two lead desingers. I guess they couldn't carry a tune.

 

[vc66]

Drafting is basically a language to translate design intent into manufacturing. So if the engineer doesn't understand drafting (whether he does the drafting or not), then I don't see how he/she is going to be able to convey their design to anyone else (be it drafter, machinist, or the like).

If you had a shaft with a bunch of steps and cutouts, you should know the best way to dimension the shaft to convey design intent while still making it as easy as possible for the machinist. If you dimension everything all-over the place in the model (not from the end at which the machinist will chuck the part in the lathe, for example), then you're either a)giving the drafter extra work for fix your model, or b)giving the machinist extra math to do, that could have been avoided by your "knowledge" of drafting.

Laziness is akin to stupidity, in my opinion.

V

 

[MadMango]

I have seen my fair share of drawings on the shop floor where the machinist had calculated "new dimensions" simply because they didn't feel like changing his set-up. Usually their response was, "Its all adds up."

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

Have you read faq731-376 to make the best use of these Forums?

 

[KENAT]

Which in fairness, as long as the tolerances from the new set up meet the tolerances from the drawing set up, it does.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[ewh]

Yes, not all machinists approach all parts in the same manner. As long as he can produce an acceptable part based on the original tolerancing, the machinist should be free to approach it as he sees fit.

"The ambassador and the general were briefing me on the - the vast majority of Iraqis want to live in a peaceful, free world. And we will find these people and we will bring them to justice." - [small]George Bush, Washington DC, 27 October, 2003[/small]

 

[CheckerRon]

Well the GD&T mantra I have heard over and over is: "Dimension for inspection. Let the shop figure out how to make it."
That doesn't mean you don't consider manufacturability, it just means you don't cater your dimensions to accomodate manufacturing vs function and inspection.

 

[MechNorth]

The standards are the same ... the skills have degraded. My university engineering program was one of the last in Canada to have a decent drafting course, that was way way way back around '88 (not 1800's, either). We had two profs; one drawled on about nothing of value to the course, and the other was considered an anal-retentive-bastard ... the kind that should be teaching the basics so that you get it right! Many of my colleagues that went to other schools didn't do much CAD, never mind a single board drawing.

With the high degree of automation in CAD, some designers don't even have to lay out the views & dimensions, much less actually apply GD&T. If you're seeing solid lines instead of hidden lines, it's likely because the CAD administrator isn't a mechanical engineer, and doesn't realize that line thickness & style actually convey information, and therefore haven't set the basic settings appropriately.

Within the Western, industrial-based economies, we've seen a continual degradation and "dumbing-down" of design, machining, finishing and inspection processes within industry. We slid into a rut that we couldn't dig our way back out of. I've seen a mixed bag of quality (engineering, manufacturing & inspection) coming out of lesser-developed industrial countries, and they've been quickly catching up to and surpassing our abilities, with a fraction of our infrastructure costs. If they're producing comparable quality (good or bad) at a fraction of the cost, is it any wonder we're in a tail spin?

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com

 

[ewh]

"...an anal-retentive-bastard ... the kind that should be teaching the basics so that you get it right."
My kind of job, if it only paid better!;-)

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]