A torque sensing assembly includes a first sensor assembly configured for sensing at least a portion of a magnetic field of a first portion of a rotating shaft assembly and generating a first signal. The hollowed-out section is located between the head and the cylindrical bearing surface. The resin supply system has a regulator for maintaining the spraying air pressure of the resin coating composition in each nozzle of the spraying unit at a predetermined respective value. Alternatively, the dual mode input device can also be an optical trackball.