Abstract: An improved pneumatically operated automatic screw driver system for affixing screw devices into objects. The inverted screw-driving system utilizes a locator guide and locator to pre-position and align a screw device relative to the object that is being driven into. Drawing the object against the locator and the pre-positioned screw automatically imparts rotation to the aligned screw even before contact is made between the screw and the object. The construction of the locator and locator guide is such to absorb the initial torque developed by the driver, and the locator is spring-loaded within the locator guide so as to maintain the driver in the operably "off" position until the locator guide is depressed to activate the air motor and thus rotate the screw device.