n Figures 220 and 221 is a drawing of a
connecting rod drawn, put together as it would be for the lathe, vise or
erecting shop.

[Illustration: Fig. 218.]

[Illustration: Fig. 219.]

[Illustration: Fig. 220.]

[Illustration: Fig. 221.]

To the two views shown there would be necessary detail sketches of the
set screws, gibbs, and keys, all the rest being shown; the necessary
dimensions being, of course, marked on the general drawing and on the
details.

In so simple a thing as a connecting rod, however, there would be no
question as to how the parts go together; hence detail drawings of each
separate piece would answer for the lathe or vise bands.

But in many cases this would not be the case, and the drawing would
require to show the parts put together, and be accompanied with such
detail sketches as might be necessary to show parts that could not be
clearly defined in the general views.

The blacksmith, for example, is only concerned with the making of the
separate pieces, and has no concern as to how the parts go together.
Furthermore, there are parts and dimensions in the general drawing with
which the blacksmith has nothing to do.

Thus the location and dimensions of the keyways, the dimensions of the
brasses, and the location of the bolt holes, are matters that have no
reference to the blacksmith's work, because the keyways, bolt holes, and
set-screw holes would be cut out of the solid in the machine shop. It is
customary, therefore, to send to the blacksmith shop drawings containing
separate views of each piece drawn to the shape it is to be forged; and
drawn full size, or else on a scale sufficiently large to make each part
show clearly without close inspection, marking thereon the full sizes,
and stating beneath the number of pieces of each detail. (As in Figure
222, which represents the iron work of the connecting rod in Figure
220). In some cases the finished sizes are marked, and it is left to the
blacksmith's judgment how much to leave for the finishing. This is
undesirable, because either the blacksmith is left to judge what parts
are to be finished, or else there must be on the drawing instructions on
this point, or else signs or symbols that are understood to convey the
information. It is better, therefore, to make for the blacksmith a
special sketch, and mark thereon the full-forged sizes, stating on the
drawing that such is the case.

[Illustration: Fig. 222]

As to the material of which