FASTENER REFERENCE

Screws, Nuts, Thread Data & Driver Sizes
METRIC COARSE THREAD (ISO 262)
SIZE PITCH (mm) TAP DRILL
(Internal) (mm)		 CLEARANCE
(Pass) (mm)		 MAJOR DIA
(Rod / Die) (mm)
METRIC FINE THREAD (ISO 262)
SIZE PITCH (mm) TAP DRILL
(Internal) (mm)		 CLEARANCE
(Pass) (mm)		 MAJOR DIA
(Rod / Die) (mm)
UNIFIED COARSE (UNC)
SIZE TPI TAP DRILL
(Internal)		 CLEARANCE
(Pass)		 MAJOR DIA
(Rod / Die)
UNIFIED FINE (UNF)
SIZE TPI TAP DRILL
(Internal)		 CLEARANCE
(Pass)		 MAJOR DIA
(Rod / Die)
UNIFIED EXTRA FINE (UNEF)
SIZE TPI TAP DRILL
(Internal)		 CLEARANCE
(Pass)		 MAJOR DIA
(Rod / Die)
NATIONAL PIPE TAPER (NPT)
SIZE (Nominal) TPI TAP DRILL (Internal) EXTERNAL DIA (Pipe OD)

NPT CHARACTERISTICS

NPT threads are tapered at 1/16" per inch of length (3/4" per foot). They rely on "thread interference" to create a seal, often requiring thread sealant or PTFE tape.

HEX SOCKET (ALLEN) - METRIC
SCREW SIZE SOCKET CAP
ISO 4762		 BUTTON
ISO 7380		 COUNTERSUNK
ISO 10642		 SET SCREW
ISO 4026
TORX SOCKET - METRIC
SCREW SIZE SOCKET CAP
ISO 14579		 BUTTON
ISO 7380-2		 COUNTERSUNK
ISO 14581		 SET SCREW
ISO 14580
HEX HEAD / NUT WRENCH SIZES - METRIC
BOLT SIZE HEX BOLT
ISO 4014/4017		 HEX NUT
ISO 4032		 FLANGE BOLT
ISO 1665		 FLANGE NUT
ISO 4161
PHILLIPS / POZIDRIV
DRIVER SIZE METRIC SCREWS IMPERIAL SCREWS
SLOTTED (FLATHEAD) / JACKSCREWS
BIT WIDTH (mm) METRIC SCREWS APPLICATIONS

PROPERTY CLASS (METRIC)

8.8 - Medium carbon steel, general purpose
10.9 - Alloy steel, high strength
12.9 - Alloy steel, highest strength

SAE GRADE (IMPERIAL)

Grade 2 - Low carbon steel, general purpose
Grade 5 - Medium carbon, quenched & tempered
Grade 8 - Alloy steel, high strength

METRIC TORQUE VALUES (Nm) - DRY
SIZE 8.8 (Nm) 10.9 (Nm) 12.9 (Nm)

TORQUE ADJUSTMENT FACTORS

Lubricated threads: Reduce torque by 25-30%
Loctite / thread locker: Reduce torque by 15-20%
Zinc plated: Reduce torque by 15%
Cadmium plated: Reduce torque by 25%

TECHNICAL REFERENCES & STANDARDS

THREAD & CLEARANCE

ISO 262 / 724: Metric general purpose threads
ISO 273: Clearance holes for bolts & screws
ASME B1.1: Unified Inch Screw Threads (UNC/UNF)

MECHANICAL & DRIVERS

ISO 898-1: Properties of carbon steel fasteners
ISO 4762 / 4014: Socket head & Hex bolt standards
DIN 5264: Slotted driver tip standards

PRECISION & MINIATURE

NIHS 06-10: Miniature threads (NIHS/ISO 1502)
ISO 1364: Phillips/Pozidriv cross recesses