Abstract: A spiral cutting anvil is provided with indicia along its length, and a series of aligned gaps through which a cutting blade can be passed. A cutting blade comprises the working portion of a cutter assembly pivotally fastened to a slide plate which can be located at various positions with respect to the anvil. An adjustable stop is disposed at an appropriate point along the spiral, as determined by the indicia, and a length of packing material extends from the stop along the anvil to one of the gaps. The cutting blade is then urged through the gap, in guillotine fashion, to sever the packing at the correct point.