Abstract: Apparatus used with a yarn warper or beamer to uncross yarn ends that have become crossed during a warping operation. An element shaped like a knuckle moves back and forth across a side of the yarn sheet while protruding into the path of yarn ends making up that sheet. The motion of the knuckle against the side of the yarn sheet raises each yarn slightly, then allows the yarn to return to its original position. This motion dislodges yarn ends that have become crossed and allows them to return to their proper registration in the yarn sheet. The end uncrossing device may be located either downstream or upstream from the comb assembly in a warper.