A case erector is configured to open folded cases. In one example, the case erector includes a planar bearing surface. A semi-circular channel is defined in the planar bearing surface about a center point. Additionally, a notch is located so that the planar bearing surface does not extend to the center point of the semi-circular channel. A plate is in contact with the planar bearing surface. The plate has at least one flange sized for travel within the semi-circular channel so that the plate rotates against the planar bearing surface in a circular manner about the center point. A notch is defined in the plate so that the plate does not extend to the center point of the semi-circular channel. An arm is connected to the plate so that the plate and the arm rotate together with respect to the planar bearing surface. In operation, a folded edge of a folded case is positioned at the center point. One or two arms, moved by plates rotating on bearing surfaces, attach to and open the folded case.