BS 2827 Pressed Machine Screw Nuts

BS 2827:1957 specifies general dimensions and thread limits for pressed machine screw nuts in square and hexagon forms. It covers BA and Whitworth-form threads and applies to ferrous and non-ferrous materials. The standard cautions against using these nuts where appreciable stress is expected.

Technical line drawing of square and hexagon pressed machine screw nuts with thread, width and thickness references

Nut forms and thread families

Pressed nut form	Thread family	Material scope
Square	BA	Ferrous or non-ferrous
Square	Whitworth form (including BSW and BSF)	Ferrous or non-ferrous
Hexagon	BA	Ferrous or non-ferrous
Hexagon	Whitworth form (including BSW and BSF)	Ferrous or non-ferrous

Dimensional reference

Dimension reference	Meaning	Applies to
d	Internal thread designation and nominal size	Square and hexagon nuts
s	Width across flats	Square and hexagon nuts
e	Width across corners	Hexagon nuts
m	Nut thickness	Square and hexagon nuts
Thread limits	Thread size limits and tolerances for the selected thread family	BA and Whitworth-form threads

Reference note: The drawing is schematic and not to scale; its labels are dimension references. The public BSI summary confirms the nut forms and dimension categories but does not publish the numeric schedule. Check BS 2827 for size-specific dimensions and thread limits before manufacture.