Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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double-shear stroke

The multiple movement of the descending knife of a guillotine. First, there is the downward motion through the pile being cut; second, the single-shear motion across the face of the pile; and third, the double-shear motion where the cutting edge of the knife starts to cut higher at one side of the pile and by a rocking motion becomes approximately parallel when it reaches the bottom of the cut at the table. The double-shear stroke thus cuts more like a scissors, with the knife edge entering each sheet in the pile at its side and gradually cutting across it. The advantages of the double-shear stroke are: 1) less power required to cut: 2) less strain on the machine and the knife; 3) a more perfectly cut edge; and 4) a smoother face to the pile. Cf:SINGLE-SHEAR STROKE . (145 )

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