A semi-automatic testing machine developed by J.W. Lemmens for use with its GrindoSonic system has been specifically designed to meet the need for high-volume, in-line production testing. The operator simply places the part over the hole that contains the tapping device. When the pad is correctly positioned, sensors send a signal to a built-in microprocessor, which controls the measurement process. The microprocessor assigns a sequence number to the part, directs the detector arm to extend from the machine so it touches the pad, triggers the impact hammer, receives the reading from the GrindoSonic and compares the reading with preset acceptance limits. By limiting operator intervention to the handling of the parts, the semi-automatic testing machine offers a reliable low-cost testing environment with increased productivity and produces reliable information for statistical analysis.