[SML] CAD drawing interchange

[jdunfee12 at yahoo.com]

PDFs seem to be a standard when exchanging the equivalent of prints. It is even possible to get some dimensions, but that takes a lot of effort, since you must scale first. Since I normally use the drawing as part of another drawing, I greatly prefer DWGs or DXF.   

The topic of drawing exchange is also related to the issue of how to archive drawings and designs.

PDFs can be converted or imported into many CAD programs, but the success rate varies depending on how it was generated.  If the view is not a shaded or hidden line removed version of a 3D model, it often exports as PDF just fine. though, keep in mind that a PDF line drawing is only 4 decimal places of accuracy vs. 12 decimal places for native DWG (Keep in mind that this is starting to get down to atomic precision for most things).  But, as soon as any of the rendering styles for 3D models is turned on, those exports become raster images. And those are bad news for using them in CAD drawings.
Earlier in the history of CAD programs, there was some debate about how best to archive drawings. The DWG format was not as entrinched, and Autodesk itself was working hard to keep their drawing files from being used by anyone else.  The courts put a stop to that, and now I think that DWG files are sufficient to archive files. But, PDFs are probably also a good idea, since you can view them without any CAD program. 

 3D Parametric programs like SolidWorks and Inventor are another story.  For those, I think it is still a good idea to produce good drawings, and dimension them, and export as a PDF.  If your vendor were to go out of business, you might end up with a CAD file that you couldn't use.

-Joe
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