Tracking the revision separately for part and drawing

[timbochung]

Been thinking about having a two part revision number:
1a, 1b, 2a, 3a, 3b, 3c...etc.

The idea is that minor changes (missing a dimension, adding a comment) can be tracked separately from any part design changes.

If a drawing is sent out and I have forgotten a dimension or the client would like an additional comment. I think it would be valuable to issue a new drawing with a minor rev change rather than a full blown new level - kinda like the Solidworks service packs (sp1.0 , sp1.1, sp2.0..etc)

People who see the different revision don't have to be too alarmed knowing that it is just a minor drawing revision and not a design change.

Any thoughts?

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[MikeHalloran]

I see your point, but you're on a slippery slope.
I.e., revisions that you may consider insignificant may have major impact on suppliers or customers, so you can't always know which are minor and which are not.


Mike Halloran
Pembroke Pines, FL, USA

 

[ctopher]

I have used minor revisions for a long time. As long as the change doesn't affect fit/form/function.

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

 

[MikeHalloran]

I have used them, too, for internal purposes.

Once a single print or file leaves your premises/control, any kind of informal revision system presents a risk.



Mike Halloran
Pembroke Pines, FL, USA

 

[fcsuper]

Let me modify Chris' comment. Changes can be minor as long as they don't AFFECT interchangeability, form, fit or function. Interchangeability should be the primary factor. It's not whether it is being changed, but whether it is being affected. This applies changes for subassemblies and to the component level equally, as they are generally equally affected by changes.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

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

 

[fcsuper]

About rev scheme, some companies track revisions for models separately from the drawing. Changes on the model that do not affect the spec sheet do not require a revision to the spec sheet, and vice versa. This means that you'll have to determine which affects what for the real world parts. Some some industries this is easy to track. For others, it would be impossible.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

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

 

[timbochung]

Good to hear that I'm not crazy. One idea in terms of actually incorporating this was maybe to have two revision boxes in the titleblock. One for the part and one for the drawing. On second thought - that may make it more confusing. Probably just have both fields in the same box.

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[drawoh]

timbochung,

If you want to distinguish between major and minor changes, write it up in the revision block.

"CORRECTED SPELLING MISTAKE ON SECTION A-A. NO CHANGE TO INFORMATION ON DRAWING."

"LENGTH CHANGED FROM 77.4. NO PARTS FABRICATED TO ORIGINAL RELEASE."

"ADDED TWO HOLES. ALL EXISTING PIECES MODIFIED TO NEW REVISION."

As noted above, you cannot have two parts fabricated to the same drawing, with same part number, that are not functionally identical.

JHG

 

[MadMango]

At a previous company we used Version and Revision. Revision (alphabetical) covered the Drawing, while Version (numerical) covered the 3D model. It was the first time I had seen/used a system like that. It was confusing at first, but after a few months it made some sort of weird sense. Luckily I haven't been exposed since.

The thing you need to keep in mind is whether your PDM/MRP/ERP system can handle 2 different revisions for a given part. Many will blow-up.

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

Have you read faq731-376 to make the best use of these Forums?

 

[ctopher]

MM,
That would be confusing.

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

 

[timbochung]

drawoh,

Revision block is definitely one way of doing it and certainly is "textbook" (change triangle + revision table)

Most of the jobs and clients I work for - I feel it would be overkill (i.e I'm looking for a easier/lazier/efficient way of doing things.

My feeling is that if the change is really just a clerical change and not a functional change - a small indicator is all that is needed.

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[StrykerTECH]

Wow, this is a great question and a great discussion.
Let me through some of my experience in the ring.

The important thing to realize when talking about having to track revisions, is how does the rest of the company treat the revision?

I can tell you most customers I have dealt with do not track revisions outside of the company. That is because it is very difficult from an MRP perspective to track a change that doesn't affect form/fit/function yet must be revised for various reasons. In addition almost all companies who make changes to a part that are significant enough that the new part is no longer interchangeable with the old part demand that you take out a NEW part #. This again is not due to CAD it is due to the MRP package and how the rest of the organization tracks and controls inventory. I had one customer who actually labeled ALL parts with partnumber AND rev. But after a while they realized this was expensive and didn't yield that much of a benefit since they still couldn't see how many of each REV was in inventory. Long story short, I don't know of any company who USES minor revisions THROUGH-OUT the organization. Lots of companies I work with only use that type of control during the developement process and internal to engineering. Usually these companies have that process integrated with in PDM system so to the user it is fairly a brainless automatic activity going on with out there awareness.
My recommendation, Go with Numbers . . . no minor revisions. especially if you don't have an integrated PDM.

And finally ask yourself what would be the difference in the process between a minor revision and a major revision, if the answer is "I put a small letter after the number" then it probaly is a headache in the making.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[timbochung]

Ultimately, the situation that I would like to handle in a more controlled fashion is the odd time I forget a dimension and the drawing has been sent out to the client. Normally the drawing is sent out in both pdf and an autocad format.

What I would like to avoid is saying "Ignore the previous file and let this one overwrite it.."

Again, for a missing dimension or a dxf/dwg that was exported at the wrong scale - a full blown revision is overkill and I would to save the client from looking at what is different.

Of course, the revision table would pinpoint what the change was but that just makes the designers/drafter job more difficult with more clerical work. Plus those revision tables take up alot space. If these were mass produced carefully controlled documents - then for sure, do it textbook. But for the smaller jobs - one offs, looser clients - a system to communicate minor, clerical changes, the two part system is sounding good.

Also, one more thing I've been doing lately is appending the rev to the pdf and autocad file. This way at a glance I know what is going on and if I have the two part system, the file names will be unique, no overwriting neccessary.

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[drawoh]

...

Again, for a missing dimension or a dxf/dwg that was exported at the wrong scale - a full blown revision is overkill and I would to save the client from looking at what is different.

If you are issuing drawings to customers, you need to identify which ones are correct. On preliminary design layouts, I have a note stating explicitly that the drawings are preliminary, and showing the latest date.

An any final, official communications, you need a revision letter or number. The whole point of bureaurocracy is that the left hand does not know what the right hand is doing. If I see one copy at Rev_B and one at Rev_C, I know one print is superseded, and I know which one. Notes on the drawing can be hard to spot. Cover letters and emails might not get passed on to me. I can send you an email asking what the current revision of the drawing is, thus, quickly validating my information.

JHG

 

[ctopher]

Configuration control can be a pain, but is a must control docs and files effectively.
Make your drawings/files match the ones you send to customers or vendors, minor or rev or not, then there will be no question.

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

 

[StrykerTECH]

It sounds that you would have a substantial change of process by doing this "minor" revision. I would really take are hard look at that assumption, because I bet someone else inside your organization would really like to know if you add a dimension, especially Quality or some functional group that verifies part tolerances. I know ISO wouldn't go for that. But if you are a small company and just bypass the system by saving another PDF at 1.1 instead of full blown 2.0 . . . . well . . . again I would like to know how that process would work differently.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[timbochung]

I agree that the decision to go with a minor or major rev can be arbitrary but when in doubt - go with a major rev. Having the capability to go minor I think would be a benefit. Again, the main thing I'm trying to record and facilitate more easily is the case of the missing dimension. A pdf has been sent to the machine shop and they say that a dimension is missing or could I give them this dimension. Form, fit and function isn't really changed - the info was missing or not clear. A pdf that was at 1a now gets bumped to 1b - it is a flag that 'Hey not a biggie change' and everyone gets the benefit of not overwriting already issued pdfs and a document trail of the process is intact.

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[StrykerTECH]

I think in concept it is a great idea, and it has been tried before. It probably could work in a small company. But in a large company, there is a lot more red tape. So who's responsibility is it to make sure they have the right REV. In small companies maybe you have a process to make sure they always pull the latest REV, WHEN that is done is a huge question. But what your saying could work, it just comes down to if you are to blame for not making someone else aware that there is another print out there, you can bet this process will burn you eventually. This again is assuming you are just going to make the minor change and save off the PDF as 1.1 . . . . so a drastic difference between that and going through all the notification paperwork with a 2.0 rev.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[timbochung]

Making sure that the person has the right rev is always important - big company or small. As I hash out some more - perhaps a good rule of thumb would be: "If they are making the part to rev 1a and I then give them a drawing with new rev - will this drawing change the part? If no - then a minor rev is all that is required. Again, this is to capture the missing dimensions that slip through.

Strytech does raise a good point about scalability. Would this work in a bigger company? Traditionally, all drawings get bumped to a new rev, no matter what the change was. This system definitely does work but then we must ask ourselves, does it create extra work, is there a better way to do it?

The rev block does take time to do, adding the descriptions is a pain and the rev block takes up valuable real estate, Of course, certain products do require this type of control but I feel that many do not.

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[PeterStock]

Notification of the change is a must for a minor change as well as a major change. What is not required is the complete approval process that a major change would need. Define your minor change process formally and have someone qualified to know the difference make the call which one to use. I would include notification process include all the departments that would need to approve a major change. If any objected, the eco would become a major change to approve.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net