Nails, Screws, Bolts, and Other Fasteners - Carpenter's and Builder's Math, Plans, and Specifications - page 27

Ta ble 1-10 Safe Loads for Lag Screws
(Inserted across the grain)
Diameter of Screw in Inches

Kind of Wood 1

1 / 2 5 / 8 3 / 4 7 / 8

White pine 590 620 730 790 900

Douglas fir 310 330 390 450 570

Yellow pine 310 330 390 450 570

somewhat different plan from that of Rugg's, but no doubt was
a further development of the first machine. Oliver's machine was
known as the English Oliver.
The construction of the early machines was carefully kept secret.
It is related that in 1842, a Mr. Clark had his bolt-forging machine
located in a room separated from the furnaces by a thick wall. The
machine received the heated bars through a small hole, cut in the
wall. The forge man was not even permitted to enter the room.

Kinds of Bolts
One commonly used bolt is the carriage bolt , which got its name
from its prime early use: assembling horsedrawn carriages.
To install a carriage bolt, a hole (equal to the diameter of the
shank) is bored. The bolt is then slipped into the hole, and a hammer
is used to pound it down so that the neck seats well in the hole. A
nut on the other end completes the job. It can be screwed on without
having to hold the other end of the bolt.
Another type of bolt is the machine bolt , used on metal and wood
parts (see Figure 1-24). The machine bolt is slipped into the hole
and a wrench is used to hold its large square head on one end while
another wrench is used to tighten a nut.
Figure 1-25 shows various types of bolts and Figure 1-26 shows
a lock washer used on some types of bolts.

Proportions and Strength of Bolts
Ordinary bolts are manufactured in certain stock sizes. Table 1-11
gives these sizes for bolts from 1

/ 4 inch up to 1 1 / 4 inches, with the

length of thread.
For many years, the coarse-thread bolt was the only type avail-
able. Now, bolts with a much finer thread (called the National Fine
thread ) have become easily available (see Table 1-12). These have
hex heads and hex nuts. They are finished much better than the stock