We have a series of line drawings, actually they are excavation layouts that we need to scan and convert into graphics for a training video. They have many rounded edges and we are trying to avoid drawing them from scratch or trying to trace on top of them. I scanned the line drawings at 450dpi. Took them into Photoshop, used a combination of the fill and stroke tool and got pretty good result. The drawings have some imperfections on the curved lines which are causing a problem. Any tips that can help me get perfect curves from the line drawings without tracing them from scratch. Also, these were done on a CAD system, any way to get from a CAD file to an Illustrator file so we would have a rastorized graphic. We are losing it because they have to print the line drawings.
Many CAD programs will allow you to output dxf or dwg files which can be read into illustrator. The problem is that these formats rarely use curves to define shapes. Instead they use short line segments. You could use the OBJECT/PATH/SIMPLIFY command to convert linear paths to curves with some degree of control but unfortunately you will probably find that the short line segments are not actually contiguous (joined). If they are they may not break and end where you want them to so the amount of pre simplification work required would make this method time-prohibitive.
A high resolution scan autotraced with a high tolerance may be your best bet, though line intersections will likely cause problems with this method as well.
I can't offer much more help than that. Try playing with these two options and see how they work for you.