wheels the ribbon immediately adopts a curled state and in that form is transported for storage or packing the tightness of curl is a function of ribbon tension over the blade and the precise approach angle chosen fig3 illustrates the effect of means not shown which permit variation of the approach angle to blade 17 a by varying the height of the curling blade 17 a above the spool the curling arm 18 being fixed movement of curling blade 17 a may be in response to a screw threaded adjuster and in the direction indicated by arrow 23 alternatively the curling arm 18 may be moved vertically with respect to a fixed blade as indicated by arrow 24 the diameter of the wheels 31 33 should not be such as to stress the u201c wrong u201d side of the ribbon thereby causing permanent shear stresses to be imposed in opposition to the stresses applied by the curling edge 17 the idler wheel 34 is optional but provides a convenient way of guiding the ribbon to the shredding device 35 in the preferred embodiment the shredding device is mounted on means not shown which permit the shredding blades to be engaged and disengaged from the ribbon as desired in place of the blower 36 a fence or other means of stripping the ribbon from wheel 32 could be provided in some embodiments and with suitable attention to wheel design the.