Self-tapping screws — what each size fits
Machine screws go into an existing thread. Self-tappers cut or form their own, which is how most plastic housings, appliance panels, TV backs and ducting are actually held together. 79 documented uses across 17 sizes.
Sheet-metal & thread-cutting (ISO 1478 / DIN)
Hardened screws for steel, aluminium and enclosure panels. The ST number is the outside thread diameter in mm.
ST1.93 documented uses · pilot 1.5-1.6 mm in 0.5-1.0 mm steelST2.23 documented uses · pilot 1.8-2.0 mm in 0.5-1.0 mm steelST2.63 documented uses · pilot 2.2-2.4 mm in 0.5-1.0 mm steelST2.95 documented uses · pilot 2.4-2.6 mm in 1.0-1.5 mm steelST3.55 documented uses · pilot 2.9-3.2 mm in 1.0-2.0 mm steelST3.93 documented uses · pilot 3.3-3.5 mm in 1.0-2.0 mm steelST4.25 documented uses · pilot 3.6-3.8 mm in 1.0-2.0 mm steelST4.85 documented uses · pilot 4.1-4.4 mm in 1.0-2.5 mm steelST5.55 documented uses · pilot 4.8-5.1 mm in 1.5-3.0 mm steelThread-Cutting (Type 23/25, DIN 7513/7516)6 documented uses · pilot 3.3-3.5 mm for M4/6-32 in die-cast zinc
Plastic thread-forming (PT, Plastite, WN1412)
Wide-pitch screws that displace rather than cut plastic, so the boss does not crack and the screw can be refitted several times.
Looking for threaded machine screws instead? Browse M1.2–M6 sizes.