Validating 3D models from 2D drawings 4

[shaneca6]

We recently switched from Autocad to Solidworks. We have a sister company in India that is going to convert the majority of our 2D drawings to 3D models as well as recreate the drawings. The problem I am having is finding relevant information on how to validate all of the data coming to us from India. Does anyone have knowledge in this area? I could use all of the help I can get! *girl smiles.

 

[IRstuff]

"I'd rather have a bottle in front of me instead of a frontal lobotomy..." I always thought that was just a hilarious quip as a teenager, hearing that on Dr. Demento. But, it seems to be much more profound as I grow older.

Not an ME type, but I'd agree that your company will take years to recover from this. As this project starts to overrun, there will be great efforts taken to shortcut the process, and those drawings involved will suffer greatly. Actually drawing checking will be minimized to save costs, and all sorts of mistakes will propagate. Even the first drawings that get the mort scrutiny will have transcription errors, and new errors introduced because of the new software. A worst-case scenario is that you'll find, at the end of the process, that something fundamental was done incorrectly, and that every drawing will need to be retouched; hopefully that's just my paranoia.

As a wise person once said, "If it ain't broke, don't fix it." Seems like a lesson to relearned, and relearned, and relearned, and ...

TTFN

FAQ731-376

 

[Tmoose]

we sold some of our technology (Engineering standards, guidelines, product drawings) to one of the main players in this industry over in India. They have created drawings for a few newly designed products, and we are "vetting" some of the tech calculations, etc based on their contract specs. Curiously They have chosen to have us build several of the major components for one of the first jobs on a rush basis, so gave us their drawings, reportedly made by them using Solidworks. We are in the "build to print" position. A guy in design graphics has been doing some high level checking on the side. He is discovering There are plenty of serious problems with some vary basic stuff on their drawings. Weld symbols pointing to sections of a single cast component. 8 bolt flanges mating to 16 bolt flanges. Basically these expensive assemblies would be unbuildable as they stand without major rework at assembly.

Previously we had been talking to them about "converting" one series of our existing drawings (mostly paper scanned as TIFs) to solid models to ease designing new products of different sizes.
I don't see how that project could succeed without 100% checking of everything they do.

 

[KENAT]

In fairness, it's not just an 'outsourcing to India' problem.

We tried vaguely similar to another company in the US and it really didn't work out well. Basically we had drawings for an existing product that were not of a high standard and limited what machine shops etc. we could use - basically we had to use the shop that worked out the bugs 10 years ago during prototype and had their own set of red-lines or similar and could charge whatever they wanted.

So we found a company that seemed to have some pedigree/reputation. Basically told them to check some drawings to correct errors and bring up to current drawing standards etc. We made a reasonable effort to state our expectations, gave them copies of our DRM, some ground rules, some functional info...

They did a pretty poor job, no apparent understanding of GD&T beyond the most basic level.

We then paid for them to incorporate the charges and they started charging us for training time for them to train a new checker or something like that.

That was the end of that experiment as far as I know.

It can be difficult enough to get new/contract employees to do things 'the right way' let alone another organization entirely, let alone another organization in another time zone.

Posting guidelines faq731-376

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

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[tr1ntx]

Tmoose,

Yeah, several years ago I figured out that an "engineer" in India could be some guy who went to a 6 month Vo-Tech type program and learned how to operate the CAD system. Having the remotest clue of what it is he's trying to CAD is not a requirement. I guess they don't like the term "drafter". But even then, I've seen stuff where even if you title them "apprentice beginning drafter, Jr. grade", their work wouldn't be up to snuff.

Now they're all geeked up touting SolidWorks' feature-based 3D modeling as the greatest thing since sliced bread, but if they don't have sense enough to do it correctly, the program is not a panacea. Garbage in, garbage out.

 

[shaneca6]

Time will definitely tell if we are headed in the right direction. The more I get feedback the more I think we should re-evaluate the concepts behind the decisions.

I did make a point to ask my boss what the relevance was of converting old and outdated product to 3D and also to find out why we needed to recreate drawings and he stated that our old drawings are very flawed and needed revamped.

I left it alone and crept back to my desk to quietly weep!

Does anyone feel sorry for me yet? *girl smiles

I could probably start about 20 more threads to see if any of the other tasks I have been assigned have been accomplished successfully in the past.

I don't want to relearn lessons....dispite what my momma may say behind my back. *girl laughs

 

[drawoh]

shaneca6,

Been there.

The advantate of copying your 2D stuff into SolidWorks is that you wind up with a library of existing stuff to use in new designs. This is an advantage of 3D CAD in general.

SolidWorks comes with a DWGeditor that reads AutoCAD files. There are some Mikey Mouse CAD programs that read and write them too. Once AutoCAD is purged from your machines, you still can get at and edit your old files.

Perhaps you can get your boss to work out priorities. If you have stuff that is currently being manufactured, that must be supported, and that may be installed in new designs, you want this stuff imported into SolidWorks.

I have imported a lot of AutoCAD drawings into SolidWorks. The best method is to reproduce your old drawing, however crappy it is. This makes the new drawing easy to check, since you are just reproducing the old numbers.

If something is being done wrong, you, your drafter, or your checker should generate a formal change request. I think this is appropriate. Importing drawings into SolidWorks is one task. Fixing bad GD&T is another task. Maybe your change review committee or the original designer will not agree with you about your change.

JHG

 

[KENAT]

Well, lets just say I fell a bit more sorry for you than at least one Eng-Tips poster did for me: thread1103-216008

Seriously though, the fact you aren't just looking to cookie cutter copy the drawings, but are looking to correct/update them makes things a whole lot trickier.

Good luck.

Posting guidelines faq731-376

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

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[MintJulep]

...our old drawings are very flawed and needed revamped

But you are using them to make parts. Right?

So it seems to follow that somewhere there is a collective tribal knowledge of how to really make each part.

Your machinists have little back note books. Your vendors have have marked up prints. You have CAM tooling files that are "tweaked" from the drawing.

How do you collect this tribal knowledge and communicate it to your Indian brethren so that their end product will be "right"?

I'd say you're doomed.

Sorry.

 

[DesignerGuy16]

We have a number of machines still made from AutoCAD drawings that are utter garbage. Thing is, they have made due for 15+ years.

My opinion on the matter is kind of the way we're handling this same issue. Leave them be until you want to revamp that product. Then start over with a white sheet of paper and redesign everything and basically obsolete, or recreate the existing AutoCAD parts as needed.

Blindly recreating existing drawings is not really a good way to go. You really need to consider the whole picture. Also the way the models are created might create a nightmare for making changes, etc later on. Ie, consistency and modeling practices will make or break you later on with this. That's why a fresh look is a good thing. You'll be able to better see fitup issues, problems with dimensions, etc.

James Spisich
Design Engineer, CSWP

 

[PeterStock]

At my last job a tool was worn out and a new tool had to be made to replace it. After the new tool (designed to the part drawing' a housing I think) started to produce parts it was found that the part could not be used in the assembly. The part had been produced out of tolerance, but all the mating parts had been adjusted to fit the "bad" housings. Something to keep in mind when converting files. Make sure the drawing is updated to match the parts that are working, but are out of print.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[berkshire]

Mint Julep said,
""Your machinists have little back note books. Your vendors have marked up prints. You have CAM tooling files that are "tweaked" from the drawing.""

Many years ago when working for a large aircraft manufacturer, my department ran into this exact problem.
The company had a Yoder multiple roller mill on which the Z sections for fuselage frames were made. These were later stretch formed to shape. The company farmed this job out and shut down the roll forming line.
The new sub contractor sent in the Z sections that were perfect to the engineering drawings. When they were stretch formed they were 1/10" undersized.
On a hunch I grabbed my supervisor and we went to the rolling mill area, where the machine used to reside, and found the old foreman’s desk. Inside was a 40 year old marked up print, increasing the dimensions by (you guessed it) 1/10". This information was forwarded to the engineering department who made the appropriate corrections. This little bit of tribal knowledge had lurked around the company for ever.
In spite of the company and FAA directives that marked up prints were not to be used.
B.E.

 

[tr1ntx]

I keep seeing hints of this general concept that SolidWorks leads to better parts (more accurate) than AutoCAD. Dia12.397 +.002/-.002 is the same whether I model the part it SolidWorks, AutoCAD, or sketch it on a napkin. I've seen countless examples of dimensional errors in SolidWorks models, but since there is the general concept that it is "magic", the greatest thing since sliced bread, and never does wrong, the drafter is able to blame it on something/someone else.

I use 3D in AutoCAD all the time. In some ways, such as designing geometrically, I like it better than SolidWorks.

 

[shaneca6]

Hello All,

The feedback I am getting has been great. I did want to mention that we pull drawings every single time the part is made and the programs are pulled in the same fashion and then compared to the drawing. The drawings follow the parts all of the way through to assembly.

I am not sure how other industries handle the drawings (if they are a once and done until changes are made). Granted, the most major of problems we have came across thus far is over dimensioned/under dimensioned drawings.

We are handling this on a family basis and not starting the next family until we are confident the work is done correctly. The process is very daunting and slow.

I am starting to see both side of the fence on this issue and can definitely see value in leaving well enough alone and also redoing everything to make sure it is correct (not that 100% accuracy is attainable) *girl winks.

Bright side...I've quit crying about it and have put on my big girl pants to move forward! HaHaHa

 

[gadkinsj]

I have had 2 separate experiences with this with 2 different companies.

Both Essentially kept all engineering controls on the drawings and didn't worry about keeping controls on the 3-d models.

The first company was a smaller (30 engineers) fabricator of high precision aircraft parts. Friday all 2d drawings were live with UG. The following Monday all 2d drawings were converted to frames and every drawing change required a new 3d model that the engineering staff would make and then create the new drawing from. This gave a lot of opportunity for training and if something wasn't broken (35 year old drawings) nobody tried to fix it.

The second company. (200ish engineers in my department) has had 2 different 2d packages and are now converting from Pro-E to Catia. Same thing. Drawings are all that matter to us and models are just the means to create them. We are converting the models but don't really care that much if they create the proper drawing until it becomes time to change them. Then if its wrong you fix it or recreate the model and move on. We expect to see about 5% of the models come through bad. Haveing 5% of the drawings get changed overnight to something different with no person checking them sounds like a problem I wouldn't want to deal with.

 

[shaneca6]

gadkinsj,

We do currently have someone checking them. Which is the good part. From what I gather, there is no one good way to validate the data. Which is what I was afraid of. We are putting workflows in place that prevent a "green light" on the models until they are adequately (relatively loose term at this point) checked to the original 2D data. At that point they will be approved in the workflow inside of ePDM.

Luckily, I control the workflows so I do have a small amount of decision making abilities. *girl smiles.

Thanks for the feedback, it is always appreciated.