Form of thread defined. Tables: basic sizes from 0 B.A. to 25 B.A. Dimensions and tolerances for a ‘normal’ series from 0 B.A. to 16 B.A.; and for a ‘close’ class from 0 B.A. to 10 B.A. Recommended gauging system, tables of inch equivalents, in appendices. Data on bases of B.A. sizes, allowances and tolerances.
