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Machining is in general conducted in multiple paths and thus residual stress and subsurface damage formed by previous cut may influence subsequent cutting. Ceramics materials are extremely brittle and prone to cracks. Ultra-precision machining with very small depth of cut enables ductile mode cutting. There have been various reports that critical depth of cut (CDC) for single crystal sapphire exists, where the ductile to brittle transition occurs. However, the CDC of subsequent cutting changes due to the influence of residual stress and subsurface damage by previous cut. This study investigates the indirect effect of residual stress and subsurface damage on the critical depth of cut of the second cut by analyzing the plastic deformation mechanisms activated during 2-step machining on A-plane of sapphire. It was found that the [1#100] machining orientation was most suitable since the critical depth of cut remained fairly constant due to dominant rhombohedral twinning activation during subsequent machining operations.