Hi, i am newbie in autocad 3d modeling. I have downloaded 3d engine model in .stp format and converted it to .dwg.. now trying to get 2d section planes from it.That is how 3d model looks like in autocad : http://img837.imageshack.us/img837/9577/blockreference.jpgAnd this is example of what i need to get from 3d model: http://img248.imageshack.us/img248/7899/sectionplane.jpgI think that i can't get that kind of drawing from 3d model, so i would be satisfied if i could get just section plane with exact measurments.. I tried tu use SLICE function, but it slices only solid object.. And i can't convert it in to the solid (i get message : objects cannot be converted '')Any help? any ideas?

You'll have to try to convert it to a solid.  What is it now a mesh?

I'm attaching a link to .dwg file with one part of that engine, maybe it will be more simple. http://www.2shared.com/photo/XuAaaAGF/Filter.html

You won't be able to do much using AutoCAD 2007.  Too old.Try Inventor or Inventor Fusion.

i have autodesk inventor fusion.. but it didn't helped me... probably because i dont know how to use it.. now trying to download autocad 2014.

Is the object comprised of surfaces, a mesh, splines or just regular polylines?It sounds as those you might have to convert the object to a 3D solid first.