counterbore

[ koun-ter-bawr, -bohr; koun-ter-bawr, -bohr ]

Phonetic (Standard)IPA

noun

a tool for enlarging a drilled hole for a portion of its length, as to permit sinking a screw head.
the portion of the hole so enlarged.

, coun·ter·bored, coun·ter·bor·ing.

to enlarge (a drilled hole) along part of the length of the hole by drilling with a bit having a greater diameter.

First recorded in 1605–15; counter- + bore ²

That it may always do this and yet leave sufficient clearance, the counterbore has been devised.

The jaw end is counterbored out with a 45-degree counterbore to form a bearing for the forward end of the micrometer screw.

For enlarging a hole for a certain distance the counterbore is employed.

A counterbore in the arbor hub provides clearance for the hub of the pulley which projects beyond the rim on one side.

For counterboring small holes or for facing the metal around their ends, the form of counterbore shown in Fig. 1746 is employed.

April 18, 2024petrichor

[pet-ri-kawr]

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