A modified hopper design of the conventional cassava grater and its concomitant productivity improvement is presented. One of the sides of the inverted truncated rectangular pyramidal hopper was hinged at the lower end and swung through angle of 15 to 30 degrees. This flapper swing served as feed for the rotary grater. The flapper allowed the cassava tubers to be fed over a larger grater surface area permitting cassava feed over an angle of 120 degrees instead of the usual 90 degrees. It further allowed the variation of the space between the rotary grater and the hopper thereby enhancing complete maceration of the tubers. The presence of ungrated cassava chips in the macerated mash common feature with conventional graters was reduced to negligible proportions. A process improvement of up to 100 per cent in thru-put was obtained compared with the conventional graters.