The surface roughness is one of the most important characteristics of machined parts. A systematic method is proposed in the paper to simulate the shape generation processes in the boring operations and to estimate the surface roughness of the generated faces, based on the machining parameters. The simulation model includes both the models of the shape generation motions considering kinematic motion deviations and the cutting tool geometries. The shape generation motions with deviations are mathematically described by 4 by 4 transformation matrices. A set of points on the bored holes are generated through the simulations, and an assessment surface is obtained as the datum reference to estimate the 2-dimensional (2D) and the 3-dimensional (3D) surface roughness, based on the points generated by the boring process simulations. The proposed method provides us with a systematic method to estimate the surface roughness in the boring processes including the kinematic motion deviations.