Table 3-11.-Lag Screw Sizes
eighths, screws from 1 to 3 inches increase by
quarters, and screws from 3 to 6 inches increase by
half inches. Screws vary in length and size of shaft.
Each length is made in a number of shaft sizes
specified by an arbitrary number that represents no
particular measurement but indicates relative
differences in the diameter of the screws.
nomenclature of a screw, as shown in figure 3-81,
includes the type, material, finish, length, and screw
size number, which indicates the wire gauge of the
body, drill or bit size for the body hole, and drill or bit
size for the starter hole. Tables 3-12 and 3-13 provide
size, length, gauge, and applicable drill and auger bit
sizes for screws.
Table 3-11 gives lengths and
diameters of lag screws.
Figure 3-81.-Types and nomenclature of wood screws.
Bolts are used in construction when great strength is
required or when the work under construction must be
frequently disassembled. Their use usually implies the
use of nuts for fastening and, sometimes, the use of
washers to protect the surface of the material they are
used to fasten. Bolts are selected for application to speci-
fic requirements in terms of length, diameter, threads,
style of head, and type. Proper selection of head style
and type of bolt results in good appearance as well as
good construction. The use of washers between the nut
and a wood surface or between both the nut and the head
and their opposing surfaces helps you avoid marring the
surfaces and permits additional torque in tightening.
Carriage bolts fall into three categories: square
neck finned neck and ribbed neck (figure 3-82).
These bolts have round heads that are not designed to
Figure 3-82.-Types of bolts.