To return the sharpness of the shallow notch of a file is unlikely, but this small, flat tool can make a handy cutter for Plexiglas, textolite and other soft sheet materials. Sharpen it on the grinding wheel, as shown, and fit a sliding stop. Tooth I will help to cut through the detail in a straight line, the cutter II with a focus — to penetrate the circle and the tooth III — to make a notch in the plate of soft metal to facilitate bending.
Y. ZHIDKOV