Countersink

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countersink

[′kau̇nt·ər‚siŋk]
(design engineering)
The tapered and relieved cutting portion in a twist drill, situated between the pilot drill and the body.

Countersink

 

(Russian, zenkovka; from German senken, “to sink, lower”), a cutting tool used for countersinking. Countersinks usually form part of a set with centering drills. The sizes of countersinks in each set depend on the diameter of the hole; in all sets, the vertex angle is 60°. Coun tersinks are made for chamfering center holes with diameters of 0.5 to 1.5 mm (ordinary countersinks), for holes with diameters of 0.5 to 6 mm (with or without protective taper), and for holes with diameters of 8 to 12 mm (with tapered stem). Countersink cutting elements are made from high-speed steel; countersinks with tapered stems are welded and the stems are made from carbon structural steel.

countersink

countersink
A boring bit having a conical-shaped cutter; used to make a depression to receive the head of a screw or bolt so that it does not protrude above the surface.