Machine Screw Size Calculators have been prepared to present dimensions of machine screw sizes according to ASME B18.6.3 "Machine Screws and Machine Screw Nuts" standard
Some important notes from the ASME B18.6.3:2003:
Machine screws with slotted and recessed heads, flat countersunk head, oval countersunk
head, undercut flat and oval countersunk heads, flat and oval countersunk trim heads,
pan head, fillister head,
truss head, binding head, hex head, hex washer head, round head and round washer
head are covered.
The Standard also covers flat trim head, oval trim
head and drilled fillister head machine screws and gives cross recess dimensions and gaging
dimensions for all types of machine screw heads. Information on metric machine
screws are given in B18.6.7M standard.