ew showing a corner of the head in front of the head be
given, the same fact holds good, as is shown in Figure 159. That the two
outside flats should appear in the drawing to be half the width of the
middle flat is also shown in Figure 158, where D and E are each half the
width of C. Let us now suppose, that the chamfer be given some other
angle than that of 45 degrees, and we shall find that the effect is to
alter the curves of the chamfer arcs on the flats, as is shown in Figure
160, where these arcs E, C, D are shown less curved, because the chamfer
B has more angle to the flats. As a result, the width or distance
between the arcs and line G is different in the two views. On this
account it is better to draw the chamfer at 45 degrees, as correct
results may be obtained with the least trouble.

If no chamfer at all is to be given, a hexagon head may still be
distinguished from a square one, providing that the view giving three
sides of the head, as in Figure 158, is shown, because the two sides D
and E being half the width of the middle one C, imparts the information
that it is a hexagon head. If, however, the view showing but two of the
sides and a corner in front is given, and no chamfer is used, it could
not be known whether the head was to be hexagon or square, unless an end
view be given, as in Figure 161.

[Illustration: Fig. 160.]

If the view showing a full side of the head of a square-headed bolt is
given, then either an end view must be given, as in Figure 162, or else
a single view with a cross on its head, as in Figure 163, may be given.

It is the better plan, both in square and hexagon heads, to give the
view in which the full face of a flat is presented, that is, as in
Figures 155 and 163; because, in the case of the square, the length of a
side and the width across the head are both given in that view; whereas
if two sides are shown, as in Figure 161, the width across flats is not
given, and this is the dimension that is wanted to work to, and not the
width across corners. In the case of a hexagon the middle of the three
flats is equal in width to the diameter of the bolt, and the other two
are one-half its width; all three, therefore, being marked with the same
set of compasses as gives the diameter of the body of the bolt, were as
shown in Figure 152. For the width across flats there is an accepted
standard; hence there is no need to mark it upon the drawing, unless in
cases where the standard is