Historical
ISO 521:1975
Machine chucking reamers with parallel shanks or Morse taper shanks
Lays down only metric dimensions. For each type of reamer mentioned above ISO 521 gives two tables, one showing preferred sizes with corresponding dimensions and the other, a general table set out as functions of diameter steps. Provision is also made for tolerances on length, cutting diameters and the diameters of parallel shank.
International Organization for Standardization [iso]