Auxiliary device for measuring roughness of crankshaft conical surface

The invention discloses an auxiliary device for measuring the roughness of a crankshaft conical surface. The auxiliary device comprises a base, L-shaped positioning blocks, V-shaped positioning plates, knob screws, first positioning nuts, second positioning nuts and first positioning bolts; an installation trough hole is formed in the center of each of sides where two short edges are located, on an upper surface of the base; one knob screw is arranged in each installation through hole; two parallel waist-shaped through holes are formed in the two knob screws on the upper surface of the base; the two opposite L-shaped positioning blocks are arranged between the two knob screws on the upper surface of the base; each L-shaped positioning block includes a horizontal portion and a vertical portion, wherein the horizontal portion of one L-shaped positioning block is arranged above the two waist-shaped through holes; and one V-shaped positioning plate is fixed on the vertical portion of eachL-shaped positioning bloc