TP-6270 11/06 Appendix 59
Appendix D Common Hardware Identification

Screw/Bolts/Studs

Head Styles

Hex Head or Machine Head
Hex Head or Machine Head
with Washer
Flat Head (FHM)
Round Head (RHM)
Pan Head
Hex Socket Head Cap or
AllentHead Cap
Hex Socket Head or Allent
Head Shoulder Bolt
Sheet Metal Screw
Stud

Drive Styles

Hex
Hex and Slotted
Phillipsr
Slotted
Hex Socket

Nuts

Nut Styles

Hex Head
Lock or Elastic
Square
Cap or Acorn
Wing

Washers

Washer Styles

Plain
Split Lock or Spring
Spring or Wave
External ToothLock
Internal ToothLock
Internal-External ToothLock

Hardness Grades

American Standard

Grade 2
Grade 5
Grade 8
Grade 8/9 (Hex Socket
Head)

Metric

Number stamped on
hardware; 5.8 shown 5.8
Allenthead screw is a trademark of Holo-Krome Co.
Phillipsrscrew is a registered trademark of Phillips Screw Company.

Sample Dimensions

1/4-20 x 1
Major Thread Diameter In Fractional Inches Or Screw Number Size
Length In Inches (Screws and Bolts)
Threads Per Inch

American Standard (Screws, Bolts, Studs, and Nuts)

Metric (Screws, Bolts, Studs, and Nuts)

M8-1.25 x 20
Major Thread Diameter In Millimeters
Length In Millimeters (Screws and Bolts)
Distance Between Threads In Millimeters
9/32 x5/8x1/16

Plain Washers

Internal Dimension
Thickness
External Dimension

Lock Washers

Internal Dimension
5/8