Threaded bolt in Rhino 3D.

There is little use of including the thread of a bolt in a 3D scene, particularly as while rendering it is better use a texture. Nevertheless the exercise is interesting as it teaches some Rhino tricks.
The basic trick is that in order to make a spiral thread one has to use two spirals, and the command sweep 2 rails, to produce a tangential spiral thread surface
The pictures are there for support, while making your own 3D model.