To bore out (a hole) to a larger diameter for a given depth.

noun. A tool-holder or tool-bar for a drilling-machine.

noun. A tool for boring out a portion of a hole to a larger diameter.

noun. An enlarged section of a drilled hole, made for the purpose of receiving the cylindrical head of a screw or some similar object.

noun. A flat-bottomed cylindrical enlargement of the mouth of a hole, usually of slight depth, as for receiving a cylindrical screw head.

noun. A kind of pin drill with the cutting edge or edges normal to the axis; -- used for enlarging a hole, or for forming a flat-bottomed recess at its mouth.

transitive verb. To form a counterbore in, by boring, turning, or drilling; to enlarge, as a hole, by means of a counterbore.

noun. A cylindrical recess, typically machined around a hole to admit a screw so that it sits flush with a surface.

noun. The tool with which a counterbore is machined.

verb. To create such a cylindrical recess.

noun. a bit for enlarging the upper part of a hole

"- Did he set the correct rotational speed and were counterbore diameter and depth correct?"

countersink  spotface  

bit  

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