The calculation of the diameter of the drill is to be derived from the conicity.    From Wordnik.com.  [8. Special recommendations for making conical bore holes true to size] Reference

Empirical values for the preliminary fitting-in of taper pins of a conicity of 1: 50.    From Wordnik.com.  [8. Special recommendations for making conical bore holes true to size] Reference

It consists of a long, conical cutting portion of a certain conicity (for instance 1: 50); the shank is equipped with a square so that it can be received by a tap wrench.    From Wordnik.com.  [3. Construction of hand reamers] Reference

A conicity of 1: 50 means.    From Wordnik.com.  [8. Special recommendations for making conical bore holes true to size] Reference