Recently, demands have increased on fabricating complex and accurate structures by ultra-precision cutting. However, the machinability is influenced by crystallographic orientations in micron/submicron cutting. In our past work, it was clear that the crystal anisotropy affected the elastic recovery in submicron groove cutting of single crystal copper. Before the experiments, three-step cutting, i.e., rough cutting, intermediate cutting, and finish cutting, have been employed to flattening single crystal copper surface. The depth of affected layer was thinned by increasing the number of intermediate and finish cutting. Nevertheless, few microns of affected layer remained on finished surface. The rough cutting step is considered to cause the remaining affected layer. In this paper, we have investigated the effect of cutting conditions of the rough cutting step to reduce the depth of affected layer. The Schmidt factor of each slip system was calculated from measured cutting forces. Results suggest that the slip system and its Schmidt factor may explain the machinability, and results indicate that the thickness of affected layer decrease with an increase in cutting speed.