Abstract: An improved web guide structure of the self-adjusting type for a corrugated web single-facer machine including a plurality of laterally spaced guides for continuously and yieldably urging a corrugated medium web against a lower corrugator roller, a support rigidly mounted to the single-facer for pivotally supporting the guides, and a gravity-actuated and adjustable biasing means for urging the guides against the corrugated web at preselected pressures. The guides preferably include a trailing guide portion that remains in engagement with an adhesive applicator roll when the roll is moved out of engagement with the corrugated web to maintain alignment of the guides with the roll. Springs may also be used in conjunction with the support to apply greater or lesser pressure to all of the guides simultaneously.