When Nilda makes yarn on a drop spindle, she holds a fluff of wool in one hand, gently pulls, twists and turns the soft wool until she teases out a strong length of yarn. She continues to wind the yarn onto the shaft (the stick) of the spindle until she has made enough to wind into a ball.
The round disk at the end of the shaft provides weight and balance so that the spindle drops straight down as Nilda pulls and twists the wool.
