Abstract: An electrode tip for electric spot welding is formed with a hole which extends from one side of the tip to the end surface of the tip and is arranged to receive one end of a radiant energy conveyor which is intended to transmit a signal indicative of the temperature reached at the end surface of the tip. An insert is fitted within the hole with interference and arranged adjacent to the end surface of the tip in order to ensure the continuity of the said end surface.

Abstract: In order to determine whether the screwing home of a threaded element, such as a screw, by a power tool has been acceptably executed, the number of revolutions undergone by the threaded element during the screwing operation is measured as a function of time. The revolution-time function derived for the screwing operation is compared with a reference function corresponding to an acceptable screwing operation. The comparison shows up unacceptable screwing operations and can be performed both visually and by a microcomputer. Apparatus for effecting such monitoring of screwing operations includes sensing means for measuring rotation of the output shaft of the power tool and circuit means for processing the output of the sensing means and effecting the comparison with the reference function.