Steel S.A.E. 1112 cold rolled specimen was cut orthogonally at slow speed of 0.625 ipm, and the shear plane formation was examined from a series of photographs taken during a cut for cutting triangular wavy surface and for the case where the straight surface is cut by the tool moving along the triangular wavy path. It was found that the shear angle variation is approximately given by equation (3) of the text. An explanation for this shear angle variation is provided by the consideration of the state of stress around the singular point at the free surface.