Abstract: High-speed spooling machines for yarn or thread are subject to the difficulty that, if the yarn or thread should break between a yarn cleaning, that is, size sensing and cutting apparatus and the takeup spool, stray remnant filamentary pieces may occur due to operation of the cutter apparatus since the thread size sensing apparatus may provide an erroneous "cut" signal upon absence of any thread in the sensing field. To prevent such operation, a thread sensing element is interposed in the path of the thread being spooled which, upon break of thread, will provide a "no tension" signal which will be below a predetermined threshold level. This signal is then used to inhibit operation of the cutter, regardless of the output of the thread size sensing element.