TM 5-2330-325-13&P
0095
FASTENER SIZE AND THREAD PATTERN
NOTE
Unless followed with "LH" (e.g.,3/4-10 UNC-2A-LH), threads are right-hand.
Threaded fasteners are categorized according to diameter of fastener shank. Thread styles are divided into
broad groups, two most common being coarse (Unified Coarse-UNC) and fine (Unified Fine-UNF). These
groups are defined by the number of threads per inch in the bolt shanks. In addition, threads are categorized
by thread class, which is a measure of degree between threads of the bolt or screws (external threads) and
threads of attaching nut or tapped hole (internal threads). The most common thread class for bolts and
screws is Class 2.
Table H-4. Thread Classes and Description.
EXTERNAL
INTERNAL
INTERNAL
1A
1B
LOOSE FIT
2A
2B
MEDIUM FIT
3A
3B
CLOSE FIT
NOMINAL SIZE
NO. THREADS/INCH
THREAD SYMBOL
THREAD CLASS
3/4
10
UNC
2A
466-0106
Figure 3.
Fastener Size.
LENGTH
GRIP
(BOLT SHAFT)
LENGTH
HEIGHT
BODY
THICKNESS
OF NUT
LENGTH
OR HEIGHT
OF HEAD
NOMINAL
DIAMETER
THREAD
THREAD
RUNOUT
LENGTH
LENGTH
466-0107
Figure 4.
Thread Pattern.
END OF TASK
END OF WORK PACKAGE
