Definition of counterbore in English:

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Pronunciation: /ˈkaʊntəbɔː/


1A drilled hole that has a wider section at the top.
Example sentences
  • In the new design, the holes are formed with a lead-in chamfer to facilitate pushpin insertion and a counterbore formed inside the hole that creates a shoulder to hold the pins in place.
  • A counterbore surrounds each rivet receiving opening in the flat bottom surface.
  • This is followed by a two-pass drilling operation to produce the counterbore and the bolthole.
1.1A drill whose bit has a uniform smaller diameter near the tip, for drilling counterbores in one operation.


[with object]
Drill a counterbore in (an object): dies are counterbored to prevent material build-up
More example sentences
  • The end of the sleeve inside the mount was shortened and counterbored to accommodate the 0.16 NA beam.
  • If the wood is thicker than three-fourths of an inch, you can either substitute longer screws or counterbore the interior surface of the door or drawer so that the screw head is recessed into the wood.
  • It is an optional tiebar style with mounting holes drilled and counterbored for 1/4 inch SHCS.

For editors and proofreaders

Line breaks: coun¦ter|bore

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