叉口的宽度和深度尺寸，取决于叉形针所带动的纤维量来确定，叉位的轮廓和形状、叉口尺寸及深度不应大于工作部位直径的30%。在针杆两旁的凹槽可以保护和带引纤维，及降低穿刺力。
The dimension on width and depth of placket is subject to the quantity of fabrics pushed forward by furcated needle. The configuration and shape of prong position, and the size and depth of placket should not exceed 30% of the diameter of functional position. The fillister in both sides of the needle-bar can protect and carry fabrics and reduce puncture force.
