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

 

[KENAT]

MechEng2005, many CAD systems have some way of semi automatically creating a dumbed down or simplified assembly (although I haven't come across one that works really well yet) so I don't think it's as much of a concern as you do.

KENAT, probably the least qualified checker you'll ever meet...

 

[Bester2]

I can't believe that my rant has turned into such an interesting discussion. I see everyone's point and I live in an ideal world where everyone is fair and cut throat corporations do not exist. In the end that is not how the real world works. Hence my dream speech ( I am surprised no one has given me an amen or at least a chuckle, I thought that it was pretty funny. I guess I have an acquired sense of humor).

Drawoh,

I also agree, you will never get rid of human error but at least only one human is involved and you know where the error is from. How many times have you been given a part and QC inspects the part, then manufacturing gets the part and it does not fit. Then you have to track all the parties involved to see where the error lies. This can take FOREVER and some times it never gets resolved.

MachineDesign2005,

I have been given such models from vendors of proprietary parts, and re engineered them ( I guess I am just part of the evil corporate empire after all) so I know what you mean.

Once again everyone thanks for contributing to the discussion.


SW 2007 SP 5.0

 

[KENAT]

Bester, your dream didn't really adress tolerance definition or mention design documentation verification so no amen from me;-).

KENAT, probably the least qualified checker you'll ever meet...

 

[drawoh]

Bester2,

Here is an interesting case for you.

Most of the stuff I design is machined, in small quantities. I get some sheet metal, and I have done a few weldments.

Recently, I designed a casting, and I sent it out for rapid prototyping. I have a couple of limit and fit issues.

In 2D or 3D[ ]CAD, I model everything to the nominal size. If I have a 50mm shaft and hole, I model both pieces at 50mm, and I apply tolerances. For drafting in 2D, this allows me to rethink tolerances at the drawing level.

I doubt that the rapid prototype shop looked at my drawings. They worked off the 3D[ ]model, modeled at nominal size. The 50mm nominal dimension was outside the acceptable tolerance range, and the shop fabricated to the nominal.

Obviously, the next time I do rapid prototyping, I will have to rethink my modeling techniques.

Rapid prototyping is relatively easy, as far as I can tell. What happens when a machine shop uses your 3D[ ]model to generate a precision part? CNC programs take into account the exact diameter of the cutter. Someone has to load the correct tools into the machine.

One of my impressions of 3D[ ]parametric CAD is that, however capabable and productive it is, it is not idiot resistant. There is a whole lot of stuff that does not work unless you follow good modeling techniques.

JHG

 

[ewh]

Amen! But then again, there has yet to be a process that is idiot proof.

When the people fear their government, there is tyranny; when the government fears the people, there is liberty. - [small]Thomas Jefferson [/small]

 

[KENAT]

Drawoh, for modelling, especially if potentially used to directly programm CNC or create a mold/part from, best practice as I've been taught it is to normally model at mid tolerance range. There are some exceptions but I do most of my modelling this way. It makes it a bit more awkward to use the ISO style +.1/.2 on shaft -.1/.2 on holes from nominal dia type dimensioning but at least some CAD systems supposedly handle this OK.

As a general comment, ith true MBD (as I understand it) most of the thought & effort that used to go into drawings gets put into the model, including tolerancing etc.

IT DOES NOT MEAN YOU DON'T NEED TO WORRY ABOUT TOLERANCING OR SETTING DATUMS ETC.

KENAT, probably the least qualified checker you'll ever meet...

 

[Bester2]

Okay,

I was always told to model at max material conditions and apply the tolerance as annotations. Obviously in order for this to work the programs would need to be able to interpret the annotations in the drawings and apply it to that feature. Rapid prototyping machines are not that smart.

As far as taking into consideration the exact diameter of the cutter, I imagine a digital scanner that scans the tool right before the cutting process is started. (Hay if I want to think big I should go all the way).

Design documentation is easy, you release the model inside some sort of web portal that locks your model. That would give you document control because the web portal would keep a copy of the exact model that was downloaded (I used one of these while I was working for a defense contractor). You would also have to define annotation views.

There is not a huge technical hurdle to overcome for this to happen. All of these programs are just that programs. There just needs to be linking programs written that can make one CAD system talk to each type of CNC machine and each type of CMM. This would amount to roughly 10 billion different linking programs (OK I may be slightly off but this is a hurdle, not technical just manpower). Once again this is all just a dream, please don't take it to seriously.

Also about the seats of SW. You would not have to buy full seats of the program. I was in a shop that had this go between program that was unable to create features but had all other features of modeling, exploded views, measuring, annotation views, and so on. I need to find the name of the program and I will post it.


SW 2007 SP 5.0

 

[KENAT]

Bester, I can see modelling at max material being good for tolerance checks but based on what I've been told it would be a PITA for using the model data directly in CAM type applications, maybe I've been mis informed.

KENAT, probably the least qualified checker you'll ever meet...

 

[KENAT]

thread732-222977 may be relevant.

KENAT, probably the least qualified checker you'll ever meet...

 

[MechEng2005]

I don't see how a software program could create a simplified assembly that would alleviate the concerns from my previous post. However, since my work uses 2D software, I am fairly ignorant when it comes to modeling (although I have used 3D parametric in previous jobs and college). A lot of what information to include is more of a personal judgement call. Unfortunately, (affordable) computers haven't been able to replicate judgement very well.

-- MechEng2005

 

[drawoh]

KENAT,

If it were me generating a model to be rapid prototyped by someone who did not bother reading drawings and other annotations, all my geometry would be at the median tolerance.

There are alternate solutions to this problem.

None of my part geometry is so complex that it cannot be modeled quickly from one of my drawings. I have taken advantage of this for design checking purposes.

JHG

 

[KENAT]

MechEng, I've seen versions in both Solid Edge & Pro E and seen the results from Solid Works if I recall correctly. None are perfect, especially if you throw in translating to generic format and then into another system but they do exist and work up to a point.

drawoh, loathed as I am to make concessions to manufacturing ;-) this is one case where I believe it may make sense to do so. If they have to adjust every dimension in the CAM program to allow for tolerances it removes some of the benefit of being able to import the model in the first place.

I'm not saying they shouldn't still be expected to look at the drawing to review tolerance, or that it's never appropriate to use min, max or uneven bilateral but modelling mid range seems to help them with inconveniencing me most of the time.



KENAT, probably the least qualified checker you'll ever meet...

 

[MechEng2005]

KENAT - I will yield to your superior knowledge. =)

And I suppose that even if the software did not completely alleviate all the concern, 2D drawings could be made for the sole purpose of customer documentation. Typically, in my field, the customer assembly drawings don't take long to generate anyways, since they usually only include overall dimensions, structural mounting locations, and a BOM.

-- MechEng2005

 

[ctopher]

It's just like everything else in every generation. As long as there are still some of us around doing 2D and making drawings, they will not go away.
Drawings and 2D drafting will have to be breed out of people to go away. The younger generations will rule with 3D models and no drawings. It's reality.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[HgTX]

Industry-dependent. And maybe dependent on develoments in display technology, too. There's no way something on a small screen (and yes, 24" is small; laptops are even smaller) can compare to a large sheet that you can see your whole piece laid out on and still be able to read, and that you can carry around with you and scribble on. (Carry and scribble are taken care of by a small tablet PC, but then you're looking at the thing through a tiny window.)

Hg

Eng-Tips policies: faq731-376

 

[drawoh]

ctopher,

It's just like everything else in every generation. As long as there are still some of us around doing 2D and making drawings, they will not go away.
Drawings and 2D drafting will have to be breed out of people to go away. The younger generations will rule with 3D models and no drawings. It's reality.

I design stuff that gets installed in aircraft. The installers want templates for drilling holes. A laptop with a 44"x32" screen that you can safely drill holes through is way more expensive than a sheet of paper.

Here in Canada, architects work in metric, and construction people work in English units. All drawings are converted. There are an awful lot of people you are going to have to retrain before the future arrives.

JHG

 

[ctopher]

drawoh,
I also work with aircraft. The future is slowly creeping up on us. These workers will eventually be retrained or replaced. It may take 20+ years, but it will happen.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[ewh]

I also work with aircraft, and any templates we use are considered manufacturing tools, not drawings. They are plotted, used and disposed of. They are not maintained in DDC as a drawing file, but as part of the model file.
Yes, there will need to be major retraining, but it was the same situation with the switch from the board to CAD. The excuse "because that's the way we've always done it" doesn't fly.
Hg is correct, some industries cannot yet make the change because of their nature. That doesn't mean it won't ever happen, just that it is still on the horizon. I don't think it will be too long before you will be able to carry a hardened laptop and a thin sheet monitor of any size that you need, rolled up as if it were a blue print. Then that excuse will go away.

When the people fear their government, there is tyranny; when the government fears the people, there is liberty. - [small]Thomas Jefferson [/small]

 

[ctopher]

I hate that comment..."because that's the way we've always done it" ! I have actually witnessed an engineer get fired for that comment by the VP of engineering.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[11echo]

Well I've been trying to keep my hands off of this thread for sometime ...I've "preached" extensively on another thread, but my "better sense" is on vacation right now so I think I'll indulge!
...SO when did you ever see a welder or machinist with a computer screen so he could fabricate a part? They STILL use the old fashion 2D drafted drawings! Only the clients, designers and engineers get to see the 3D stuff. And surprise, the parts still get made! Engineers think they are selling a concept or idea only and in fact they are, something like a chief preparing a $200 a plate dinner. BUT the meal is carried by those 2D drawings and what would the client think if that meal was served on a "used paper plate"!?? ...No matter how good the meal was!
Same thing with drawings! You may not like them but they carrying your idea to the client and then to the construction people. Decades of standards and procedure have been generated to insure there is a "proper" way to document drawings. And if you’re the engineer then that's not your job! It belongs to the designer/draftsman ...and if they can't handle it, then you or your company needs to find Lead person that can! ..Not an easy find in alot of cases ...but that's another story. My $0.02!