292 (#380) ############################################ WOOLLEN AND WORSTED SPINNING » twist of such a diagram as Fig. 84, specially designed by Mr. King, of the Bradford Technical College. This judgment may be aided by the following recorded experiments : (a) Lustre yarn twists—5° to 12°. (6) Hosiery worsted twists—12° to 15º. (c) Normal worsted and soft woollen twists- 15° to 20° (d) Normal woollen twists—20° to 25°. (e) Twist for greatest strength—221° to 25°. () Twist for voiles, crépons, etc.-30° to 45°. 2. Insight as to the effect upon the fibre angle of the folding twist inserted. Thus, as shown in Fig. 85, there are six possibilities in twisting twofold yarns, of which the most important are :- (a) Converse twist-usually “ balanced in which the twofolding just balances the single twist, the result being that this yarn comes directly from the spinning frame in a straight, non-kinking state ; (6) Straight fibre twist — in which the two- folding twist just neutralizes the single twist, bringing the fibres longitudinally in the thread. This appears to be the best all- round twist, and is suitable not only for worsted yarns, but also for thick ropes and wire cables ; (c) Concurrent twist-in which the twofolding twist more than neutralizes the single twist , both fibre angle and twist angle being in the same direction. These three twists may be defined numerically as follows:-- 292
140 141 Textile Machine