An improved process for producing an endodontic instrument (38) with a predetermined taper (80) having a plurality of flutes (94, 95, 96), each with a predetermined number of spirals over a predetermined length of the instrument are provided. The process basically comprises providing a grinding wheel (20) rotated about a first axis having a plurality of flute grinding ribs (40, 42, 44) and a rolled deformed metal grinding rib (46) extending from a periphery thereof. A rotating wire stock (12) is fed past the plurality of grinding ribs (40, 42, 44) and the rolled deformed metal grinding rib (46) at a controlled rate along a second axis so that a separate flute (94, 95, 96) is ground on the wire stock (12) by each of the flute grinding ribs (40, 42, 44) and rolled deformed metal is removed from the ground wire stock (12) by the rolled deformed metal grinding rib (46). Simultaneously with feeding the rotating wire stock (12), the grinding wheel (20) or the wire stock (12) is translated such that a distance between the first andsecond axes increases as the bar stock is fed whereby the wire stock is tapered (80) as the flutes are ground thereon.