counterbore

English

A counterbore in a piece of metal.

Comparison of countersunk and counterbored holes.

Etymology

From counter- (“against”) +‎ bore (“hole”).

Noun

counterbore (plural counterbores)

1. A cylindrical recess, typically machined at the mouth of a hole to admit a screw (such as a cap screw) so that the screw sits flush with a surface.

   Coordinate term: countersink (conical)

2. The cutter used to cut such a recess. (Also used, at less depth, for spotfacing.)

   Hypernyms: cutter, cutting tool

   Meronyms: flute, pilot (the land at the tip, which rides the hole as a guide), shank

   Coordinate terms: countersink (conical); drill, drill bit; reamer; endmill

Translations

recess-machining tool

• Dutch: verzinkboor (nl) m or f
• French: chambrage (fr) m
• Italian: accecatura f, svasatura f, accecatoio m
• Russian: зенко́вка (ru) f (zenkóvka), цеко́вка (ru) f (cekóvka), зе́нкер (ru) m (zénker)

See also

• spotface (noun)

Verb

counterbore (third-person singular simple present counterbores, present participle counterboring, simple past and past participle counterbored)

1. (transitive) To create such a cylindrical recess.

   Coordinate terms: countersink (verb), spotface (verb)