Abstract: The nut has two major faces and six lateral sides. A passage connecting two successive sides is formed in at least one, typically three corners. The passage is formed by a blind groove formed in one of the major faces of the nut, opening into a first one of the two successive sides and directed toward the other of the two successive sides and by a blind groove formed in the other of the major faces of the nuts, opening into the other one of the two successive sides and directed toward the one of the two successive sides, the grooves being of such length and direction that they have axially confronting portions and having sufficient depths for the confronting portions to interfere.

Abstract: An elongate body (1) comprises an assembly of two body portions (2, 3) and contains a plurality of intermeshing gearwheels (12A to 12D) with the first gearwheel (12A) having teeth projecting through an end opening (10) to be driven by an external toothed wheel, and with the last gearwheel (12D) being disposed to drive a milling bit (15) which projects through a side opening (11).