When the dimension is long and narrow it is usual to carry the dimensions under the drawing by dotted and dash lines, as shown below.
Arrow-heads and figures should be drawn free-hand with a common writing pen.
Usually dimensions are given in inches, up to 24 inches, as it is found less confusing; for instance, if written 1′ 1″ it may be mistaken for 11″; if written 13″ no mistake could be made.
Again, 1′ 0″ may be mistaken for 10″; if written 12″ it would not; in addition to being more distinct, it occupies less space on the drawing. In large measurements there is more room for the figures, and, therefore, they can be spaced further apart—in feet and inches.
All figures should be made of a fairly large size. Vertical dimensions should read from the right hand, thus, as shown:
Measurements of importance, such as the diameter of a circle, the pitch or distance apart of rivets and bolts, etc., should be marked in figures on the drawing. When rough or unfinished work is mixed with machined or finished portions, it is usual to mark F, or “fin.,” after the latter dimension.
In practice, at times, instead of dimensions reference letters are used, thus: