The article considers a method for centerless grinding of spherical blanks. The scheme is implemented due to the presence of a trapezoidal helical groove on the driving wheel. The schematic diagram of the proposed method largely corresponds to the traditional centerless grinding scheme, which allows the use of machine tools available in production. It is shown that in the case of centerless grinding of balls, there is an error of basing on the operational size, namely, the diameter of the spherical surface. The adjustment size is mathematically determined when performing the technological operation of centerless grinding of balls, as well as the error of the adjustment size.