Parameters of Dimension Chains of Roller Cone Drill Bits

The authors have revealed and compared the internal and external parameters that form a multi-element loop system (dimension chain) of a roller cone drill bit. The article presents procedures for the probability calculation of a dimension chain of the tool diameter, calculation of the tool diameter error because of the rotation of the cone drill bit on the bit leg, and for the calculation of eccentricity error of gage cones relative to the axis of the fitting thread for three- and four-cone drill bits. It is recommended to revise the values of dimensional tolerance for roller cone drill bits and to amend related normative and technical documentation.