20 Replies Latest reply on Jan 14, 2014 12:57 PM by Brian McEwen

    Revisions Control; should revs be kept the same at all levels?

    Stuart Coutts

      This isn’t specifically to do with the software in Solidworks, this is more of a general question for all CAD folk.

      Background

      The company I work for uses a database driven document management system. Its a bit pants to be honest but one thing it does do well is keep records of documents that are connected to each other.

      There is an ongoing debate amongst the departments about revision control between old hat engineers that can't use CAD or their file systems and the SW Experts like me.

      Our system is rather basic compared to what i've seen in other companies. We have a simple caps letter rev system that follows the same idea as the column lettering system in excel. When a part model is created its given a rev letter 'A'. The drawing is also given a rev letter 'A'. If the part model changes but does not affect the drawing. I.e. a config is added purely for use in an assembly model, properties are added etc. basically something that has no relevance to the parts manufacture. On save the part model is given a rev letter 'B'.

      The Big Question

      Option 1 - If a part model is changed but does not affect the drawing in anyway, should the drawings rev letter remain at 'A'?
      Option 2 - ...or should the drawing be revised with a statement of 'No Change to Drawing' and given a letter 'B' to match the part model revision?

      My Argument

      My argument is this, if the file storage system doesn't have the ability to keep track of which rev of a part model is connected to which rev of a drawing... it is a good idea to keep the revision letters the same so as to reduce any confusion, especially when making sure if the drawing is the latest.

      However when using a database driven file management system... where the link between a specific revision of a part model is recorded as being linked to a specific revision of a drawing, there is no need to keep the revisions the same. Because this implies that when the drawing is downloaded from the server the correct revision of the part model is also downloaded from the server. This also helps to reduce the file storage size.

      Please share your opinions on what you guys think!

        • Re: Revisions Control; should revs be kept the same at all levels?
          Corey Hinman

          Without knowing the workings of your other system, I've always preached keeping the model and drawing at the same revision level. In the case of creating an additional configuration that doesn't affect the drawing, I have created a minor change "loophole" for cases like that, fixing typos etc.

           

          It's a big CYA.....this model/assembly goes with this drawing. Documentation to match the model.

           

          My $.02

          • Re: Revisions Control; should revs be kept the same at all levels?
            Patrick O'Hern

            Would your system allow a "secondary" revision level like Workgroup does?  This would allow for minor changes to the part, while still keeping reference to the drawing rev level.  (ie:  Major Rev = A,B,C,etc. ; Minor Rev = A1,A2,B1,etc.)

            • Re: Revisions Control; should revs be kept the same at all levels?
              Roland Schwarz

              Bottom line: one way or the other, you need to keep tabs on whatever changes were made.  Whether it's an "official" revision or ECN, or an adjustment for CAD admin sake, changes need to be accounted for.  Could be as simple as adding the metadata (notes, properties, Design Binder, etc.) to the model.  ALWAYS make and file a copy before changing.

              • Re: Revisions Control; should revs be kept the same at all levels?
                Joy Garon

                Hello All,

                 

                I know some companies who do not and I know companies who do.

                At my current company we keep them in sync because downstream users were confused. For us, it's about simplification.

                 

                Joy

                  • Re: Revisions Control; should revs be kept the same at all levels?
                    Michael Dekoning

                    We also try to keep them in sync. But I'd like to throw out something I've thought about that goes back to an old employer and the "paper" days. At that company, we revised existing parts (and assemblies) to inform the shop that the manufacturing process had to be modified. This obviously required that the drawing be changed and reissued. However, if we had a minor error on a drawing that didn't affect the manufacturing process, i.e. misspellings, we only changed the issue number of the drawing. The drawing actually carried a revision number for the part and an issue number for the drawing. If a new part was being created (by tabulation), the drawing was "up issued" but not revised since a manufacturing process wasn't being altered for an existing part. We did have separate paperwork that informed the shop of a new part release. In those days, we microfilmed each drawing issue and prints were redistributed. I think you could set up EPDM in this fashion.

                     

                    Mike

                    CEPA

                  • Re: Revisions Control; should revs be kept the same at all levels?
                    Tim Webb

                    Hi Stuart,

                     

                    My experience is that most decisions on matters like this need to be driven by these criteria:

                     

                    1. Regulatory requirements your organization is responsible to (i.e. FAA, FDA, EASA, etc.)
                    2. Internal documentation requirements (i.e. ISO, AS9100)
                    3. Freedom for departments to move quickly and experience as little red-tape as possible
                    4. Stakeholder preference in this process

                     

                    Accuracy is not always the friend of productivity and mixing the two together without consideration of the other can create an unexpected bottleneck. Get feedback from the players involved, they can probably drive this process better than you can AND they will have skin in the game.

                     

                    Personal preference really has no place in this arena.

                     

                    Hope this helps

                    Tim, CEPA

                    http://www.equivaq.com

                    • Re: Revisions Control; should revs be kept the same at all levels?
                      Stuart Coutts

                      Thanks folks for your valuable input. Since I'm a bit of an amateur programmer, I generally come to decisions based on a logical approach.

                       

                      From what I'm understanding is the factors I've used to come to my original decisions about rev control were limited to the systems and the programming and what would make it efficient in a database/data storage sense. However having limited industry experience it occurs to me that I haven't considered how the system would communicate with other companies.

                       

                      I'm now starting to understand the thought process behind some of the systems that you've mentioned and that I've seen before on drawings from many other companies.

                       

                      From what I've read I think the initial step to answer a problem like this is to do the following...

                       

                      Tim Webb said...

                      1. Regulatory requirements your organization is responsible to (i.e. FAA, FDA, EASA, etc.)
                      2. Internal documentation requirements (i.e. ISO, AS9100)
                      3. Freedom for departments to move quickly and experience as little red-tape as possible
                      4. Stakeholder preference in this process

                       

                      ...then if all is well carry out the system as best suits the vendors...

                       

                       

                      Just now as I've said before we run a single level A → B → C... system where the part model can be at a different rev to the drawing, since each level only revises if there is a change to that level. However I think that in order to keep the vendors etc happy we would try not to release new parts or drawings if possible. This would require a multilevel system.

                       

                      So for instance a 'release to vendor' part at rev A will have a 'released to vendor' drawing at rev A. However in the data base this would be shown as part rev A issue 00 and drawing rev A issue 00.

                       

                      If a part model needed to be revised with a change that didn't affect form fit or function of the manufactured part the the issue number would increase to 01. But the rev would still be A. It would therefore not need to be re-released to the vendor. And if a drawing needed to be revised with a change that didn't affect form fit or function of the manufactured part then the issue number would increase to 01. But the rev would still be A. It would therefore not need to be re-released to the vendor. However if a parts length etc needed altered then the part model would be revised to B issue 00. This change would also affect the drawing which would also make it rev B issue 00.

                       

                      Our database would need to be redesigned to accommodate the new rev system. Which will take years due to the size of the company. So really the decision that id need to make would be how to work the current system to suit the 4 points made by tim and the vendors.

                       

                      Since we don't actually release parts for manufacture, we only release drawings; it occurs to me that we can edit the part models all we want without changing its form, fit or function of the manufactured part, while keeping the drawing rev the same. Because if I were to keep the drawing rev the same as the part rev the vendors would go scatty every time we released a drawing to a new rev with no change.

                       

                      To sum up, I've taken everything everyone said on board and I'm really grateful for your input. I've scraped my reasons for doing the things the way I was doing and considered a broader range of factors.

                       

                      But from everything I've taken out of what everyone's said here, I've actually found new reason for doing the things the way I was doing them. Kind of seems like a pointless outcome. But really it has shown me the downfalls of our current system and the need for something better.

                       

                      Thanks everyone again for taking the time to give your $.02!

                        • Re: Revisions Control; should revs be kept the same at all levels?
                          Brian McEwen

                          Going back to the original post

                          """ If the part model changes but does not affect the drawing. I.e. a config is added purely for use in an assembly model, properties are added etc. basically something that has no relevance to the parts manufacture. On save the part model is given a rev letter 'B'. """

                          In most cases it is good practice to keep the drawing and the part on the same revision level. But why would you bump the revision on either one if the drawing is unaffected?

                          """ it occurs to me that we can edit the part models all we want without changing its form, fit or function of the manufactured part, while keeping the drawing rev the same. "" [March 25, 2013]

                          Yes.

                           

                          If you are using EPDM or something like it - I would think you would just leave the changed part in an editing/unreleased state.  The minor part change would create a Version (when you check in the change to the PDM system) not a new Revision.   Old Version would still be available, would not change drawing - new Version would be used as part of the next Revision officially released, and for your modeling convenience. 

                           

                          If you don't change the drawing (given that your suppliers build from drawings and not part files) you don't need to Revision the drawing, so you don't need to bump the Revision on the part... I'm guessing part of the problem here is that you are not using EPDM, your other software doesn't have something like the Version counter (a fundamental part of EPDM), and so you are required to bump the part Revision letter (customized in EPDM per company policy) with any changes you check-in?  Is there any way to change a sldprt file without changing the part Revision? I think that would change how you look at this problem.