Driving Dimension Annotation Elements (DDAE)

[wbowling]

Esteemed Colleagues,



Anyone working to implement Model Based Definition (MBD) has undoubtedly noticed that it’s quite handy showing driving dimensions with Creo 2. There is also a set of switches in annotation features that lets you designate items in the annotation feature as Control Characteristics (see below). By designating these items as Control Characteristics, Windchill knows what they are.



Sadly, driving dimension annotation elements (DDAE) cannot be associated with an annotation feature. That means they cannot be designated as control characteristics.



I filed a case with PTC Technical Support (TS) and finally learned that this is intended functionality and that the tool is ‘working per spec.’ The reason I got from TS was that DDAE are associated with the features that they define and that they cannot also be associated with annotation features.



Unless and until there is an outcry of folks who want to do MBD and also want to be able to identify DDAE in Windchill as Control Characteristics, this will continue to ‘work per spec.’ MBD data flow throughout the enterprise will continue to be hampered by short-sighted CAD tool designers.



I would like to enlist the collective assistance of those of you who are trying to implement MBD in making this an issue with PTC.











W.C. (Bill) Bowling
Fellow - Engineering Design Process Development
Aerojet Rocketdyne
Mechanical Design (MS: FB24)
VOICE: 818-586-0310
CELL:805-501-4875


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[BenLoosli]

On the surface this may be PTC's easy way to account for their implementation, it may also be in the ASME Y14.41 spec that way and PTC's answer of 'working per spec' is true.

There have been many instances where the software implementation of an industry specification has been interrupted differently by different companies.
The story I like best is with the IGES format for defining a surface to be defined as a series of patches N x M. One vendor took the surfaces into N x M patches and wrote each patch out separately. When another vendor read the file in and saw hundreds of individual patches for the surface, they asked the authoring company why they did it in a manner that was totally unusable. The company reply was "The spec didn't say the resulting file had to be useable". (Company names withheld to protect the guilty.)

Does it meet the spirit of the spec, but not the intent?

Having been involved with writing company standards, there are many situations that come up that while seemingly simple may not be in the end. We spent 4+ hours one day trying to decide how long to define the field for 'Part Number' in the database when used with our CAD system. Each division was currently doing something different and had reason for doing so. Trying to sift all variations out and come up with a standard was not as simple as just saying XX characters.