external refs

It sounds like your PTC "expert" scared you away from the "evil" of external references and its stuck with you. The reason the AE's got people scared off linking things was a combination of slow computer speed relative to regen time and the fact the explicit tools to manage them, as I will explain, were not up to snuff. As in many systems, the greatest strengthscan bethe greatest weaknesses. Pro/E is such a system. External References, and all their "evil" deedswere never the real issue...the issue was the mis-use and over-use of them got MANY people in trouble from Pro/E's inception. People painted themselves into the proverbial CAD corner by linking things in ways the caused a number of issues...circular references, slow regens, missing components, relation failures etc...

For years the "missing" link was a way to explicitly manage the "external refs". they were somewhat "hidden" from the novice user. In other words, it was kind of like the wild west in the CAD world when Pro/E hit the street...lots of opportunity without the Law Man around that led to abuse and mis-use. All that "functionality" without a lot of experience led to performance issuesand horrendous modeling practices. It was something that has been addressed over the years.That is why we have PubGeom and ECG's, assembly scope settings,envelopes, simplified reps and other management toolstoday. All the functions are pretty much the same today as they were back in earlier revs now with explicit (managed and named) control. Many of us were using skeleton "methodology" before there wassuch a thing as askeleton model. Also, copying things from file to another has always been available in some fashion or another. We did it implicitly for a number of years using the master merge commands in Assembly and propagating changes back to the part level. These were "external references" that allowed thechanges to affect all the parts.Essentially the pre-cursor to Top Down Design as it's done today. As I said the earlier, the risk then was not being able to manage some of theexternal refsexplicitly. As the software evolved the "new" functionality to handle the association between parts and assemblies was added I.E Pubs and ECG's.

So, don't be scared of the "External Reference"...use it to your advantage. Skeletons, PubGeom, ECG's are your friends. Although I will caution you that over-using them can get out of hand. Pick and choose your battles and apply the functionalitywisely. I still see many people employing the functionality in ways that actually become counter-productive.

Hope it helps.

Hi Jim,

The term "external refs" can mean different things. If you are referring to Skeletons and Publish Geom then I would say thatthey are absolutely essential sooner or later. If you are referring to using a next higher assembly to position a subassembly without Skeletons and Publish Geom then you are looking for problems. Also, be aware that the average user is terrified of the word "Skeleton". I have seen users refuse to work on assemblies with skeletons in them, and I have even seen a CAD manual forbid their use because of terrified users. In fact, I tend to think of skeleton use as the defining difference between average and advanced users. Because of this, you are going to get beginner users messing up your skeletons and references. Also, sooner or later, you are going to have to clean up other people's illegal external references. I had one case where an assembly with external references was copied to a different name. When this happens, Pro/E creates new assemblies and parts that are to become your new external references. These parts are named PRT0001 and ASM0001. If these are checked in and "PRT0001" already exists in your database, (just because it is forbidden, doesn't mean it doesn't happen) your assembly may loop continuously and we call it "corrupt" because it often doesn't open anymore. I hate that! Just need to create dummy "prt0001" parts to fool Pro/E and you should be able to crack it open. Also, excessive circular references and external references can be the difference between your top assembly opening in 30 minutes or 8 hours. I have seen it... not a pretty sight. So the answer you are looking for is: Designate a Skeleton / Publish Geom expert and make sure he sits down with users that haven't touched them before. Also beware of Copy Geom. They work great the first couple of times then they tend to lose their references. Use them as a temporary reference. Then freeze the dependent components and delete your Copy Geom's before check in.

Merry ChristmaChanuKwanzzicah!

Frederick Burke