AutoCAD 2010/2011/2012 DWG Format

[#1]

I have finished drawing a 3D of a building using the combination 3dsolids, 3dfaces and exploded text and extruded to certain height.  I am using AutoCAD 2012, set up to shaded with edges, setup the dwg to pdf.pc3 to 12oo dpi.  When I plot the drawing, the output seems to be pixelated when viewed by adobe reader.   Plotting to a colored printer seems to be okay.  How can I plot 3D drawing to pdf with smooth edges?

[#2]

Are you using a visual style or Plot Shademode other than 2D Wireframe?  You may need to open Visual Style Manager.  Select the visual style you are using.  Set the Edge Settings > Show, change it from Facet Edges, to use Isolines.  The Facet Edges, looks great on screen, but causes the plots to have poor resolution.

[#3]

I have tried almost all of the options and combinations in the Visual Syles, and still get the same pixelated pdf.

I even adjusted the pdf setting to maximum 2400dpi. Plotting to a 300dpi printer is okay

Is 3D plotting printing the drawing displayed on the screen and not the drawing itself?

[#4]

Is the built-in PDF driver your only choice for PDF output? You seem to be able to print to your satisfaction to other devices, so you model and plot parameters are not the problem. AFAIK you must purchase Adobe Acrobat Pro 10 to get the best 3D PDF: if I am wrong, someone will need to be more specific than the tips provided so far that ignore the PDF driver.
Supposedly the default DWF6 driver will do what you want, try it as a test.

[#5]

I found this alternate to buying Acrobat X to get a 3D pdf driver: http://www.deskeng.com/virtual_desktop/?p=4133