Abstract: A rotary stamper includes an upper die plate assembly, a lower die plate assembly, and a support frame having a drive assembly that moves the upper die plate horizontally and vertically along a generally circular pathway while moving the lower die plate along a linear horizontal pathway. The upper die plate is vertically slidably connected to the lower die plate by way of one or more vertical rods that extend from the lower die plate assembly up through the upper die plate. In operation, the lower die plate matches the horizontal movements of the upper die plate as the latter is moved along its circular pathway. Concurrently, the upper die plate moves towards and away from the lower die plate. This maintains a substantially constant alignment between the die plates for carrying out a periodic machining operation on a moving web of material passing there between.