Abstract: A multimode testing device is disclosed for automatic testing of a threaded feature on a workpiece, comprised of a housing mounting a forward extending probe tip having an outlet supplied with air pressure via internal passages in the housing. In the first test mode, an obstruction test is made to detect the absence of the threaded feature or the presence of a broken tool, the obstruction test made by advance of the probe tip into the threaded feature. A contact of the probe tip with an obstruction causes blockage of an internal passage and an increase in back pressure therein which is detected by a pressure sensor. If no obstruction is detected, a second test mode is initiated by tilting the probe tip by an air cylinder operated actuator rod formed with cam surfaces interfit with complementary surfaces on a thrust rod mounted to push the probe tip sideways.

Abstract: An automatic fault detection system for use with machine tools to detect the breakage or absence of the tool, the presence and/or absence of a portion of the workpiece, and to prevent the normal cycle of operation of the machine when such condition exists, includes a sensor having a rod, a power port and a pair of pressure sensing ports. First and second pressure sensing switches are connected to the sensing ports wherein the failure of the sensor rod to fully retract or to advance before or beyond good check stroke position respectively exhausts the pressure sensing switches preventing operation of the machine cycle.