This study investigates the copying rate of tool motions to workpiece profiles. A machining system is developed to measure tool motions and workpiece profiles during machining processes. Tool motions are measured with a laser displacement sensor and an artifact. Workpiece profiles are measured by scanning type on-machine measurement. Sinusoidal profiles with various amplitudes are machined with a diamond tool to compare tool motions and workpiece profiles. The experimental result shows that the commanded motions and vibrations are copied on workpiece profiles. The ratios between the amplitudes of motions and profiles are calculated in the frequency domain to identify the copying rate. It is verified that the commanded motions are almost perfectly copied under the amplitudes of from 0.5 μm to 4 μm and the developed system is able to identify the copying rate under the amplitudes of from 0.5 μm to 1 μm.