Rotary impact screw driver is a tool that can be used during screw-fastening process. In applications where loads used are small, the high torque from impact driver may lead to overturn or cause the screw bit to be disengaged from the screw point. Manual screwing using switch trigger often is a challenge to the users. In this paper, the aim is to ease the screwing process and reduce the problem as mentioned. The screw driver power tool V-groove rotary-impact will be considered in this study. The physical modeling and simulation will be employed in which the motor and its rotary impact mechanism will be modeled. The speed of the motor will be controlled by the supervisory control system using state flow approach. An electronically torque control clutch is introduced to reduce the high impact torque so that the impact speed and impact rate can be slowed down too. From simulation, the lower impact torque is observed which indicates the avoidance of screw bit disengagement with the screw. As a result, the controllability of screwing process using the rotary impact screw driver can be optimized.