Rotary cutting tool

A rotary cutting tool, such as a router, especially adapted for cutting fibrous materials cleanly comprises a cylindrical body having a first group of cutting edges extending helically in a direction from one end of the body toward the other and a second group of cutting edges extending helically in a direction from the other end of the body toward the first group of cutting edges, both groups of cutting edges terminating at a zone of confrontation of the two groups. The helices of the two groups of cutting edges are of opposite hand so that the two groups of cutting edges form a herringbone pattern. The body has diametrally opposite flutes which traverse both groups of cutting edges. The confronting cutting edges of the respective groups at the zone of confrontation are axially staggered. Each cutting edge has a rake and is undercut, as a consequence of which each cutting edge has a hook-like configuration in cross-section.