channels 26 may be deeper than the circumferential grooves in both instances the teeth 25 feed the staple fibers into the circumferential grooves 27 which physically arrange the fibers in parallel relation to each other as they are delivered from the control roll the axial channels 26 assist in preventing lap ups and have an arcuate configuration which provides a negative pitch to the teeth 25 the negative pitch is desirable because it prevents the teeth from plucking and disorienting the fibers as the fibers approach and leave the control roll the work surface 24 is bounded by annular flanges 19 between the work surface 24 and the shoulders 22a 22b the flanges 19 direct all of the sliver to the control roll in fig5 and 6 the driven shaft 21 and its control rolls 20 are mounted on a roller drafter 30 between calender rolls 31 and 32 the sets of calender rolls 31 and 32 are conventional and apply heavy pressure to the sliver as the sets are rotated at different speeds to draw the sliver by passing or sliding fibers by each other causing a reduction in the size of the strand but not breaking its continuity the roller drafter straightens the fibers being treated and reduces the size of the strand which they compose the straightening is important because it arranges the fibers more nearly parallel to each other and to the direction of the strand which they compose the straightening is important because it arranges the fibers more nearly parallel to each other and to the direction of the strand indicated by the arrow in fig6 when the fibers are well straightened the arrangement helps in producing uniform strong and smooth.