BS 1804-1

BS 1804-1 specifies inch-series parallel steel dowel pins used to locate components. It defines four accuracy grades, with progressively wider diameter tolerances for the lower grades.

Line drawing of an inch-series parallel dowel pin with diameter, length and chamfer dimensions marked.

Dowel pin grades

GradePin descriptionDiameter tolerance
IPrecision-ground parallel pinTightest grade
IIGround parallel pinGround grade
IIIParallel pinWider than Grade II
IVParallel pinWidest of the four grades

Dimension references

SymbolDimensionSeries
DNominal pin diameterInch
LOverall pin lengthInch
aEnd chamfer depthInch

Note: The drawing is schematic. The full BS 1804-1 size and tolerance schedules are not reproduced here; select a nominal size and grade from the complete standard before specifying a pin.