While in the sketch do a File-Save As and you can save it as a dwg/dxf. After naming the file look on the left of the screen and select your options and click the check mark.
If you have a part and you want to export the pattern of a planar face you can right click on the face and choose export to dxf/dwg, you can also do this is you have a sheet metal file to export the flat pattern.
I see how i can choose a face or a view to export to dwg using save as, but sometimes i need to save out just the sketch like when im converting an intersection curve and i want to save that curve as a dwg. im still unsure how to save the sketch only.
While in the sketch do a File-Save As and you can save it as a dwg/dxf. After naming the file look on the left of the screen and select your options and click the check mark.
Chris