Abstract: A method of balancing a spindle in a yarn winder comprising,(a) a base for supporting a yarn take-up means,(b) the yarn take-up means including,(b-1) a spindle driving mechanism mounted to the base,(b-2) a long spindle comprising,(b-2-1) a bobbin holding portion more than 800 mm in length including a first cylindrical hollow body, a cylindrical and substantially solid body connected to the first cylindrical hollow body and a second cylindrical hollow body connected to the cylindrical solid body, and(b-2-2) a shaft extending from a center of the inner end of the cylindrical solid body along the axis thereof through the interior of the second cylindrical hollow body and projecting therefrom, the shaft being connected to the spindle driving mechanism,(b-3) bearing means for rotatably supporting the spindle on the base, and(b-4) a bobbin holding mechanism secured around the periphery of the bobbin holding portion, for detachably mounting thereon at least a bobbin for taking up a yarn,the steps which comprise bala

Abstract: A yarn winder provided with a long spindle (1) having a length of, for example, more than 800 mm, and free from vibration even when used at a high working rotation is provided by various aspects of the present invention. According to a first aspect, the dynamic unbalance of the spindle (1) is corrected by field-balancing in at least three planes including the mid-portion of the spindle (1) by an influence coefficient matrix method. According to a second aspect, the respective spindle (1, 14) mounted on a revolving drum (9) has a natural frequency different from each other so that no resonance occurs when the two spindles (1, 14) are rotated at substantially the same rotational speed. According to a third aspect, a bobbin holding portion (2) of the spindle (1) is formed by two cylindrical hollow bodies (103, 104) each having shorter length that can be easily machined without eccentricity.