To make a sectional view, the object is supposed to be cut open, and all the material removed between the cutting plane and the eye. This makes visible the hidden portion, and the drawing, therefore, consists of full lines made the same as any other, except that the material which was cut by the plane is "cross-hatched". Crosshatching consists of drawing medium width lines, regularly spaced, across the cut surface, the lines usually being at an angle of 45° with the horizontal. In case of two adjoining surfaces being cut, the lines are sloped to the right and left, respectively.
The butt joint given in Fig. 8 shows the use of crosshatching when the section taken is through different pieces of the same material. Notice the different angles at which the section lines are drawn for each separate piece.
Fig. 8. Butt Joint Showing Use of Cross-hatching When Section Is Through Different Pieces of One Material.
It is often convenient to show the kind of material of the object by the style of crosshatching. The conventional styles generally used are illustrated in Fig. 9. It is quite general, however, to use the plain form (as for cast iron), and call for the material by a specific note, thus leaving no possible doubt of the material required, and simplifying the labor of crosshatching, which is a tedious process at best. The distance between the lines should be as wide as possible, to save labor, and yet bring out the surface clearly. A good average spacing is about 3/32". Fig. 10 shows the end of a connecting rod. The section shows the different materials of which the object is made, cast iron, brass, steel, and babbitt.
Fig. 9. Conventional Representation of Materials.