Rules For Redrawing Prints?

[fsincox]

The standards seem to recognize that prints may need to be redrawn periodically, but, I am unclear of the specific requirements. Sections discuss “Superseded Drawings” and “Redrawn with Changes”.
The standard says the "Original Design Authority" is to be preserved (cage code?). Must the title block as a whole remain? Do I have to try and create another companies title block? Can I just keep the names, dates, cage code in our title block?

 

[KENAT]

I'd look at ASME Y14.35 section 4.

I'd have thought one of the common reasons for redrawing was to put it on new format after mergers etc so I'd say you can change format, including title block, so long as the required information is transposed.

Of course, if the title block of original drawing and recreated drawing closely follow the relevant ASME/ANSI standard then there wont be much difference anyway, right?;-)

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[ctopher]

If it affects fit/form/function, redraw with a new part number. A note may be added referencing/superseding the old P/N.

Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion

 

[KENAT]

I don't think that's quite the situation the OP is talking about ctopher. Also, "fit/form/function" isn't really the gold standard on change of PN, "fully interchangeable" is a bit better but even then doesn't catch all the nuances per 14.100.

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[fsincox]

Ken,
I do wish that the title blocks were that standardized as you've hinted, it would make the process much easier. To clarify the "Original Design Authory" in my case has been "assimilated" so to speak.
Thanks for the input guys, the old drawings are *.tif files from paper and we no longer have drawing boards so they send mark-ups out to be edited as *.tif files, which need redrawing for clarity (looks like heck).
Frank

 

[PeterStock]

If you are the "Original Desing Authority" you would show in the rev block something like: "REDRAWN AND FORMAT UPDATE. SEE HISTORICAL DWG FOR REV A. REDRAWN TO <CAD SYSTEM> FORMAT." followed by any actual changes. If the company name and or location has changed, I would make some reference to that change. If you have a new cage code I would also record that. If you are taking over design authority from another organization, that also would need to be recorded.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[drawoh]

fsincox,

I think it is not very difficult to model and redraw something to conform to an old print. If you apply the dimensions and specification as per the old print, the whole thing is easily checked. You need to transfer the material callout, old tolerance notes, and any other notes that might affect the part.

You can rev the part up, stating that your transferred the old drawing to a new format and otherwise, did not change anything.

If the old drawing was not done properly or at all to the current standard (ASME Y14.5M-1994?), you can cross out the note specifying the standard. The fabricator can continue to do whatever it was he was doing to make it.

If you want to change dimensions, specifications or drafting practise, you should do a separate change request and revision. Your life will be simpler if you do not redraw and repair at the same time.

I think the format of the titleblock, as opposed to the information on it, is of minor relevance. There is nothing in ASME Y14.100 that says "Here is a correct title block. If you do anything different, we will hunt you down and kill you."

JHG

 

[KENAT]

C'mon drawoh, I'm not sure any of the drafting standards say anything like "If you do anything different, we will hunt you down and kill you."

While often problematic transferring drawings from old hand 2D to cad, especially 'intelligent' 3D, it also seems wasteful to touch the same drawing twice. Heck even recreating the drawing as is can be all but impossible if folks have fudged dimensions etc. in the original 2D.

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[fsincox]

The large company that bought us, also bought them, and transfered all assets here. So the CAGE CODES are different. The drawing uses standard drafting conventional projection not "true CAD" projection and was not kept to scale as it was revised. I modeled the part for my own sanity, since the drawing does not represent the true part.
Frank

 

[drawoh]

fsincox,

The condition of your old drawings is irrelevant, unless you suspect that your fabricators are not following them.

Your fabricators should be reading the numbers off the drawings to determine dimensions and tolerances. You should read the numbers off the drawings when you create your 3D models. If your 3D models do not assemble properly, you will have to investigate to find out how the real system is being fabricated and assembled.

When you figure out what is really happening, you write ECRs, as noted above.

JHG

 

[fsincox]

If the condition of the old drawings is irrellevent then you would not need to redraw at all. If you do not believe drawing should be allowed to be redrawn then fine, that is essentually the same position my company has been taking. My impression of the standards is that there is some belief that it may become necessary from time to time and tries to layout some guidlines, I was only hoping to get some ideas on how to conform from people who have had similar situations. If you feel the standard does not allow this then fine I can see some people do not like it.
Frank

 

[ewh]

What do you mean by "standard drafting conventional projection not "true CAD" projection"?
Standard drafting convention would be either first or third angle projection, either of which are "true CAD" projection, depending on how you rotate your model.

It seems that if any of them need to be redrawn, some changes will occur that will require a drawing revision at least. I would suggest only changing them as needed, leaving the rest as "make work" assignments when such work is needed.

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

 

[dgallup]

I redraw old drawings all the time. We have bought up product lines, divisions of companies and at times complete companies. Many of these outfits were absolutely clueless about how to make a proper drawing, how to specify materials, how to apply tolerancing, etc., etc.

Yes it is difficult and time consuming and yes you have to be careful to not throw the baby out with the bath. Some of these drawings have been so bad that it is not even possible to make a physically realizable part from them. I loved the one where they drew the cross section of an o-ring in it's free state wrong. It's a circle, how hard it that to get right? If the drawings aren't too bad I just redraw them on our title blocks with the old numbers. I do reference the previous drawing.

Other product lines have had to be extensively redesigned to make them work correctly. In those cases I have taken out new drawing numbers. It's never make work, if the old drawing is acceptable we keep on using it. Usually, I'm making intentional changes so I clean up all the cr@p while I'm at it. Getting this stuff into a proper solid modeling CAD system has lots of down stream benefits too like accurate assembly drawings.

 

[fsincox]

dgallup,
Thanks, my understanding is it is much easier if they are purely commercial and not military applications. It sounds like your experiences are close to mine. These are complex large castings not simple parts either.
All,
Based on my earlier descriptions, I am assuming I am correct that we are not the “Original Design Authority”?
It seems the general consensus so far is:
I am OK with using our title block, using the original dates, names, etc and the revision block with the next revision stating: “Redrawn with (or without) changes” as appropriate.
Ewh,
ASME Y14.3, section 4 (or so), Conventional Representation. This describes the way drafting projection was done before CAD stations it was different. Sorry,you may have to have been trained as draftman before CAD to understand.
Frank

 

[ewh]

Yes, those representations have always been headaches on CAD systems.
When I was trained doesn't really have anything to do with it, only that I was trained to them. ;-)

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

 

[fsincox]

ewh,
true enough. Suffice to say that also complicates the redawing issue, but is really irrelevent to the OP which is if you are, then..

Frank

 

[KENAT]

When I was first at my current job out main task was taking some of the old drawings, the worst of which were akin to 'sketches on the back of a fag packet' and updating them to current conventions, putting them on the current companies format (it was the result of several mergers) etc.

This was done primarily so we could send them to different vendors rather than being captive to the current vendors come hell or high water.

We had a dedicated checker who went over the drawings before they were redrawn verifying form, fit, function... as well as noting drawing convention changes etc. Then they go redrawn with all these changes onto the new format, then the checker back checked them until they met his requirements.

Generally only the names, and list of rev ECO numbers got transferred to the new format title block. Most of the original companies never had cage codes, no longer existed and we weren't doing govt drawing packs so the 'original authority' part didn't really make much sense.

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[fsincox]

Ken,
Thanks, again. My understanding is the whole CAGE CODE and "Original Desdign Authority" issues are really the complicating factor here.

 

[KENAT]

Doing some research for my own question and I'll just say that ASME Y14.100 in section6.5.2.1 7 especially appendix D 9.9.2 appears to give you some info. It's not explicit but I'd interpret it as meaning that you can put the original authorities Cage code & drawing number into your format. With a separate 'current design activity' note for your co.

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[fsincox]

Ken,
Thank you for looking into it. That is basically the interpretation I would take also.
I sense they understand and accept as a given that sometimes drawings will need to be redrawn. They specifically deal with portions of that issue. The absence of any other directives seems to lead me in the direction that the rest is flexible.
Frank