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

 

[ewh]

From the other side of the fence, my money is on fewer quality drawings, especially since the introduction of CAD.

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

 

[ctopher]

I am seeing less quality from vendors. In return, they request drawings from me to be less 'technical' and without GD&T.
I think companies have become lazier and have less employees that understand drawing standards and GD&T.
It's more of a 'cost cut' in management minds.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[fsincox]

drawoh,
Thank you for moving this. I would love to know peoples impressions, I suspect there are lots of drawings out there that people will laugh in your face if you applied too much GD&T. My wife is an engineer in a company who constructs water treatment systems, again not mass production stuff. they DO NOT use GD&T. All bent brackets, weldments and lots of tubing all fabricated outside they make nothing in house. They are booming now, just the right leading edge American industry.
Frank

 

[MadMango]

Vendors will only laugh when they don't understand GD&T (or automatically increase the cost %15). Find a shop that understands it, and your cost could actually be lower. It all depends on the industry I suppose.

CAD and CAM have contributed to the downward spiral, in both the frontend and backend of the process.

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

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[dgallup]

I think CAD, particularly 3D solid modeling, has improved the quality of drawings. Maybe not dimensioning and tolerancing of the drawings. It is almost impossible to make drawings from 3D solids that are physically impossible or with discrepancies between the views or assemblies that don't fit togeather. I used to see that kind of stuff all the time with drafting boards or electronic etch-a-sketch CAD programs like AutoMAD.

 

[KENAT]

dgallup, you clearly have been blessed with more competant colleagues than I.

Just last week I was working in an assy file someone else had created and noticed some holes didn't line up.

3D CAD gives improved tools for finding these problems up front but no package I've ever used makes it impossible.

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[MadMango]

Modern CAD makes it very easy to create confusing and unnecessary drawing views. Click-click, new view... click-click, new view. I routinely see multi-sheet drawings with too many section and detail views that are not needed. The worst was a 6-sheet drawing that I was able to reduce to 3 sheets.

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

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[fcsuper]

I think that 3D CAD has averaged the quality out. There are fewer drawings written on napkins, but there are fewer drawings made by skilled and knowledgeable staff.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[fsincox]

Guys,
Do you feel the tolerances on your fabrication drawings, (castings, weldments, formed parts) acurately reflect the tolerances achieved on your parts?
Frank

 

[11echo]

I seem to remember a history class where the teacher was telling us about the “Industry Revolution of the 1890’s”. He was saying that before that time a “furniture shop” could fabricate a piece of furniture at a rate of one piece a week. This furniture was a quality piece and the cost of this furniture was high. Then the industrial revolution hit, the same shop now generated 12 pieces of furniture a week, quality wasn’t as good, but the price was reduced, and they didn’t have to have the “craftsmen” they did before. So NOW more people could now afford useable “poorer quality” furniture!
Fast forward to mid/late 1980’s owner companies, on hard times, decide to drop whole design/drafting groups, & a majority of their senior engineering people. Now opting to replace the Sr. people with wet behind the ears engineering students fresh out of school with only afew Sr. types to ride heard over the Jr. people.
Now AutoCAD pokes its head into things, with the new “Computer Revolution”! Now it’s a whole new/different way to do drawings and lot of the Sr. people in design/drafting opted to retire early as appose to have to learn a new way of doing their job. SO now it’s more important as to what computer program you know and developing your computer capabilities as apposed to developing your designer capabilities. This goes on this way for about 15 to 20 years. These days 3D is the “optimumal” way to document projects! Why? …because with 3D you generate a “pictures” where it doesn’t require anybody to be able to “read” a technical drawing. IF you’re thinking this is not true, I’m here to tell you it’s already happening, I’ve seem it! Projects are done 3D and “pictures” (with shading) are passed out to the welders. This is done because the cheaper welders don’t read drawings too well and do better with pictures!
This is the reason us “older guys” have heart ache with this whole thing. When I was taught mech. & piping drafting, it was hammered into you that your drawings WILL LOOK one way! That doesn’t happen these days. What these computer programs put out would be unacceptable pre-1985 …they DO NOT follow accepted drafting standards & convention! …SO WHY are they acceptable now!?? …Welcome to the Computer Revolution of the 1990’s!

 

[ctopher]

"Do you feel the tolerances on your fabrication drawings, (castings, weldments, formed parts) acurately reflect the tolerances achieved on your parts?"

If I communicate with the machinists and explain the drawings each time, yes. Too many machinists these days that can't read drawings. I used to give it to them and walk away, then receive good parts.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[ewh]

I can't argue that 3D models can make for a better product, but that is a different matter than the creation of a quality drawing. Drawing standards are in place to aid in the interpretation of drawings, but these standards are seldom followed completely, be it a wrong weight/font line or a dimension line/extension line cross or GD&T; most drawings today are done by engineers who usually are only exposed to a CAD program but not the intricacies of an easily interpreted drawing. So while the lines may be more consistently crisp and the lettering uniform using CAD, the actual ease of interpretation of the drawing has declined.

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

 

[fcsuper]

I don't think the furniture Industrial Age example is a one for one with the advent of the Information Age. At the heart of the current standards are hundreds of lawsuits whose precedence aren't fading away. With the adoption of 3d cad, the same level of detail and control is necessary on the model as it was on the drawing. It comes down to the fact that furniture is just furniture. Drawings or the 3d models are actual visual expression of contracts between to entities. A contract is a meeting of the minds between all signers. PO law makes on the fly contracts. If a model is sent to a vendor without proper and complete detail, there isn't a meeting of the minds. Once a dispute happens and goes to court, the customer is going to realize just how important detil is...just as it has already happened in the 1950s and 60s.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[pmarc]

Even the best CAD system we can ever imagine will not be better than the quality of a person that uses it. Of course it can make one's job quicker, drawing will be nicer to look at and easier to read, but if somebody does not know exactly what he is showing on the drawing, the content of such document will be very minor and benefits of using CAD systems will reduce significantly.

But coming back to OP's questions; I am working for automotive company that has many plants all over the world: US, Europe, India, Asia-Pacific. Different sites use different drawing and GD&T standards - US follow ASME Y14.5, Europe works according to ISO. We are of course using CAD system and producing hundreds of drawings per year, but I am very sad to say that I have not seen a single drawing that could be considered as fully done according to any of mentioned standards. Designers/drafters simply put remarks like 'Dimensioning and tolerancing according to ASME Y14.5M (or ISO 1101)' in general title block without thinking what are the implications of it. What is even worse, they do not use GD&T almost at all. And I am not talking about very simple parts like rectangular blocks or similar - geometry of our products is usually quite complicated. We have some internal rules saying that to avoid too complicated and unreadable drawings only functional dimensions should be presented, and I am OK with that, but engineers here are not even able to show these functional dimensions properly. Good example can be when symmetry of two features (let's say rectangular) is considered. Everybody will specify their widths, but nobody will care that geometrical relation between them is still missing. Most of guys will say: 'They are shown symmetrical on a drawing, so they are symmetrical, and that's all. If we add symmetry or position control on the drawing this will increase final costs of a product'.

Sometimes I wonder how lucky this company is that no serious problems caused by ambiguous dimensioning has happened so far. This might sound weird, but from my point of view (as a great supporter of using GD&T) I would like a situation to happen that somebody will come to us and say: 'Hey, there is no sufficient information on your drawing. Please fix it.' or 'You haven't specified it on the drawing, so we did as we thought, and you can not have any complaints to us that this doesn't work. If you want any modification you have to pay'. Maybe then our management would somehow realize that the company spends hard money on licences for sophisticated CAD systems to product worthless pieces of paper which instead of bringing huge profits can bring serious financial troubles.

 

[fsincox]

pmarc,
I think you and I must work for the same company/boss. It is good to hear I am not alone out here.
Frank

 

[KENAT]

However, playing devils advocate for a minute, isn't that the strongest argument against going to the effort of creating really good drawings - that often the parts received to crummy drawings do more or less work?

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[fsincox]

Kenat,
I think that is about it. I was once told the difference between an engineer and scientist was something like a scientist is on a long search for the real truth an engineer needs just to get close enough, good enough, strong enough, fast enough to get the job done.
Basically, companies only want to get the work out. Walt says: "remember, companies are in buisness to make money".
It is people like us here who care enough and are interested in perfect drawings.
Frank

 

[fsincox]

11echo,
Shall I assumue you are refering to the times when real people made real prints, a little before my time? When I first started, I worked with a guy who shaded his drawings it was beautiful art, they would shoot the guy now. Most of my time, before CAD, their was mylar repos they were pretty ugly generally and not to scale usally either, I would not call that the golden age either. I was glad to leave it, frankly
Frank

 

[ajack1]

I totally agree with you fsincox, I don’t know when this golden age was either; I must have somehow blinked and missed it. When I started out in the early seventies most design was done by hand and there was some great stuff drawn by highly skilled people but there was also some complete garbage around.

CAD is so much more than a few lines on a piece of paper, it has driven so many things forward and things are produced today that would simply be impossible without it.

Of course none of this alters the fact that the skill of the operator is still key, be that at a CAD station or on a drawing board.