Abstract / scope
Applies to single start hobs of 1 to 40 module and 25 to 0,625 diametral pitch for helical and straight spur gears. It applies to solid and inserted blade hobs. Accuracy grades are AA, A, B and C where grade AA is the highest order of precision. Gives elemental tests for hobs and permitted tolerances for the practical test consisting of the measurement of the position of the cutting edges along a line of action which requires special equipment.