How can we transfer cad files to 3dmax for drawing 3d modeling?

Answer 1

What are your SOURCE CAD drawings?
If they are ".dwg", and designed on Autocad, save them as ACAD rev 7 format (even if you are using Autocad 2007, as I do).
Then, you can import them into 3ds max 8 without problems.
See www.skytargets.com, the Dodge City game, the development of it: many tricks and multiple CAD drawings.