I Hate Drawings!!! 12

[Bester2]

I need to rant. Why do we have drawings in the 3-D world? I am so tired of arguing about the line thickness/ the font size/ the angle of the leader line or all of the other BS that goes along with creating drawings. Then you issue a fabrication to someone and they inevitably call me back asking how does this thing go together. Then I send a packaged assembly to them and there is no more questions. All they needed in the first place was the model with the associated material. Weld callouts can be called out as annotations, for that matter they should just be physically modeled. And when it comes to assembly, the model is the easiest way to show how things come together. Today you can even create video clips that can be animated with notes to show how things come together. I worked for a company once where I heard that an entire division was designed paperless. In order to do this they made all of their suppliers run the same CAD package. This allowed them to created annotations in the models along with associated views to make the parts. Do places like this really exist? If so dose anyone else see this becoming this way in the future. Dose anyone else agree with me that drawings are a waste of time? Does anyone think that their mechanical task is better served in a two dimensional world? Am I doomed to suffer in a world of arbitrary existence??

One extremely frustrated engineer that is probably looking for a new career!!!


SW 2007 SP 5.0

 

[moltenmetal]

Greg as usual has nailed this one. He too believes in the division of labour. No point in me trying to neaten up a drawing: someone who is trained to, and cares to, do the drafting RIGHT will produce a superior result for 1/2 the time and 1/4 the money than if I did it.

By the way, if it's simple and needs no modelling, a pencil sketch gets the point across right quickly. Lazy and unprofessional? Hardly. I'd call it being results-oriented.

 

[Bester2]

Well, I thank everyone for the comments. Let me start to clarify things a little. I started out in a company that did have an automotive division, that was the division that was rumored to be paperless. I worked on the production side of the house and had to read and interpolate drawings on a daily basis. I am very aware of problems that can effect form, fit, and function. Those issues need to be addresses thoroughly in the checking process. This is not a form, fit, or function problem this is more "balloon 2's parallel leader should be the same length as balloon 1's parallel leader with the bend lines matching at a vertical point." Or the example that led me to rant was "dimension x should be 44" not 3' 8" and dimension 4' 8" should be 56". The current problem that I am running into is ambiguous checking. For the dimension example it is totally arbitrary weather we should use inches or ft-inches. No rule like under 3 feet use inches and over 3 ft use ft-inches. Currently my company does not enforce any particular CAD standard. They state that we are to follow some standard but if you do follow that standard the chances of the drawing being approved are slim to none. I am a relative new engineer (3 years) but have a very seasoned draftsman that I work with (has over 25 years of experience). He is also very frustrated with the policies. The rant did make me feel better and that was the purpose. Like I stated in my first post I am probably in the wrong profession. I am still a military man at heart and this lack of standards that I can adhere to is driving me made, which is a short drive in a fast car.


SW 2007 SP 5.0

 

[ewh]

Creating good drawings without a specific standard to follow would make anyone rant.
"This is the third Tuesday in the month. Yoe can't show it that way, it must be this way."

Believe it if you need it or leave it if you dare. - [small]Robert Hunter[/small]

 

[MiketheEngineer]

I pretty much live in a 2-D world. HOWEVER - we get drawings from Architects/Engineers with virtually NO dimensions - just use the scale they say.

Right - after it has been PDF-ed and copied and then faxed - good LUCK!!

The drawing is now worthless.

On top of that - sometimes they send me a disk with maybe a thousand drawings (large building) and all of the files have names that are worthless - like 1 or 2 or 3.

It takes a day or two to find the three of four drawings I need. BACK TO PAPER!!

 

[HgTX]

Ooh, worthless file names...

We have an online file system for plans. Unfortunately, the people who develop it think of it merely as an archive, not something anyone would actually want to go into and find something in.

So those of us who actually USE the system have to put up with files in alphabetical month order (yup, all the Aprils first, ending with all the Septembers), and then within them are plan sets with thousands of pages. Sometimes someone did their job and every page shows which structure it is within the project, and what kind of bit o' structure it is (say, abutments, bents, prestressed girders, plate girders)--and sometimes there are hundreds of pages labeled "bridge plans". Nice.

Sorry to hijack the thread, but not sorry enough to refrain from proposing this...

Hg

Eng-Tips policies: faq731-376

 

[jrhagen]

I personally prefer MBD style designs. After using many Cad packages, I have found that in some cases things can be "faked in" on the drawing. I hate when people do this. It can foster errors on the drawing and will not update if a primary design change is made. When I have used MBD in the past, there was usually a company standard that governed different types of MBD parts. Anything that was different than the standard (tolerances, surface roughness, etc) was called out in a annotation view along with datums and other pertinant information. IMO MBD cuts down on the number of possible errors by cutting out the drafting process entirely. The only drawback as mentioned above by other posters is the cost. The software required to view and read MBD models can be expensive and alot of small shops simply cannot afford it.

 

[MikeHalloran]

A couple of jobs ago, I got an RFQ for an MBD part. It was a boomerang- shaped thin wall stainless steel air duct of non- constant cross section, maybe half a meter long. The tolerance was stated in a cover letter as "Within 2mm of True Position in any direction" or something like that. I could figure out a couple of ways to make the part, but I couldn't figure out how to inspect it.





Mike Halloran
Pembroke Pines, FL, USA

 

[ajack1]

Use a CMM and the model as master.

 

[TheTick]

That still doesn't explain where to align the part. To which datums?

 

[ewh]

Yep, it needs to be positional relative to something. Seems like profile would be a better control though.
But we're getting off topic here...

Believe it if you need it or leave it if you dare. - [small]Robert Hunter[/small]

 

[btrueblood]

"I personally prefer MBD style designs. After using many Cad packages, I have found that in some cases things can be "faked in" on the drawing."

I have had a lot of parts that I could describe, and show any particular view you wanted of, just fine on a 2D CAD package. The particular one I'm familiar with today, is a dovetail O-ring groove that forms the seal for a plug valve; its front view is a circle (to seal a circular cross passage).

Until the most recent revision a year ago, the 3D CAD package I use could not create the part. I would have had to "fake in" most of the detail views.

molten: "By the way, if it's simple and needs no modelling, a pencil sketch gets the point across right quickly. Lazy and unprofessional? Hardly. I'd call it being results-oriented. "

Absolutely, but you'd better have the 2D skills to do it right, or the mechanic is gonna be confused as all get out.

Bester2, sometimes you are stuck with the librarian principle, your checker sounds like the librarian who always shushes you just so she can excersize her authority.

 

[MintJulep]

"Within 2mm of True Position in any direction" or something like that. I could figure out a couple of ways to make the part, but I couldn't figure out how to inspect it.

Simple.

Inspection Plan For
boomerang-shaped thin wall stainless steel air duct of non- constant cross section

"Here ya' go client, show me where it's wrong."

 

[ewh]

I used to feel that way about a couple of checkers, but have come to appreciate what they ended up teaching me by their continued "shushing". With other checkers, however, I'd end up making a deliberate mistake, just to ease their egos and get the drawings out. Some of the wrist slapping is BS, but much of it is the process of drilling the right way to draft into your head.

Believe it if you need it or leave it if you dare. - [small]Robert Hunter[/small]

 

[Bester2]

Btrueblood,

I never heard about the librarian before. I like the analogy it seems to fit.

MintJulep,

A star for you that was the perfect answer.


SW 2007 SP 5.0

 

[drawoh]

Bester2,

I worked for a company once where I heard that an entire division was designed paperless. In order to do this they made all of their suppliers run the same CAD package.

This is really cool if you can get away with it. GM and Boeing are big enough to impose this sort of thing on their vendors. The rest of us are not.

You need to communicate with vendors what you want, and what you are going to accept. This requires accuracy, and clarity. Whatever system you use will require some equivalent of grammar and syntax. If it is not line thickness and arrow angles, it will be something else.

Also, your solution must work for your fabricator and inspector, even if they have crappy computers, and CAD software other than what you have.

About thirty years ago, I worked as inspector for a car parts manufacturer. I never saw a drawing. We used inspection fixtures to check everything. Everything was weirdly shaped, and manufactured in quantities of tens of thousands, so we had a problem and an opportunity. A paperless operation is nothing new.

JHG

 

[davidbeach]

The structural steel fabrication "drawings" for the Experience Music Project in Seattle were never committed to paper as there was no meaningful plan view available, but I'll bet that all concerned were glad to get back to paper for the next project.

 

[desnov74]

If you hate 3D CAD for manufacturing, try dealing with all the ABS/Revit crap for architectural/MEP engineers.

REVIT

 

[drawoh]

desnov74,

3D CAD can be made to work very well. Is it the CAD, or is it the CAD operators?

JHG

 

[TheTick]

One thing I like about 2D drawings is that a 2D drawing forces one to define a frame of reference or common point of view for inspection, review, and discussion. Whether 3D or 2D, a key step in documentation is to determine meaningful viewpoints to convey key design information.

 

[DesignerGuy16]

Even converting a 2D into 3D if the person is not cognizant to all of the surrounding parts and design intent it's almost assured the original intent will be lost to future use.

Drawings will always have their place. I'll agree complex surfaces ala automotive tooling is nigh impossible to detail so it's well worth it to call a blanket tolerancing and measure to the model.

For all the rest of us you still need to convey manufacturing info aside from dimensions. The dimensions need to be toleranced based on the design intent with accurate datums, etc. If you're detailing with no thought to tolerancing you're going to get crap regardless. I don't care what industry you work for. Garbage in, garbage out. I've only worked in industries so far where the engineer does the detailing and design, and I've seen some gem engineers who couldn't detail a simple block.

James Spisich
Design Engineer, CSWP