Abstract: A drill for fiber-filled synthetic plastics has an axially extending body with helical grooves spiraling from a drill point toward a shank end. The grooves define helical lands between them having helical land machining edges. At the point axially tapering land and groove point surfaces converge and land point surfaces with machining edges are radiused to merge gradually with the land surfaces rearward of them. The land machining edges are configured with a negative rake. A plurality of cross notches on the lands extending over an axially extending region of the lands from substantially the axially tapering land point surfaces a predetermined distance toward the shank end are configured to create fiber-snipping crosswise helical cutting edges with a positive rake facing the point.

Abstract: A non-circumferentially relieved surface is ground on the spiral cutting edges of an axially elongate tool using a grinding attachment mounted on a tool supporting table for linear movement to the peripheral edge of a grinding wheel having a fixed finger adjacent the revolving grinding wheel edge adapted to engage behind the portion of the cutting edge being ground to guide the rotary and axial travel of the tool relative to the grinding edge. The tool is supported on a centerless support on the attachment and a top roll is pressed down on the tool shank. The attachment and tool are moved manually forwardly on the table in a grinding pass at a speed dictated by the "feel" of the operator, and while moving the attachment and tool axially and manually revolving said roller at a speed dictated by the "feel" of the operator in timed relation to the forward movement of the attachment and tool.