An actuator is operated to move a mechanical device between two extreme positions of travel. While that motion is occurring, the system quantifies the amount of movement that occurs between those positions. The quantification may involve counting the number of steps of a stepper motor. The number of steps may be used directly as a quantification. Alternatively, the number of steps can be multiplied by the time period of each step to derive the time of the movement between the extreme positions. In addition to being used to setup the actuator upon installation, this automatic ranging method can be performed periodically to compensate for effects of wear on the mechanical device.