About Counterbores
![](https://www.mcmaster.com/prerenderstable/mvPRE/contents/gfx/small/a2bga60_abbr.png?ver=1276007986)
Counterboring—Enlarge the top of an existing hole to create a cylindrical-shaped opening with a flat bottom that acts as a seat for the head of a screw or wood plug.
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Counterbores for High-Profile Rounded-Head Screws
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The built-in pilot maintains alignment in the hole.
For technical drawings and 3-D models, click on a part number.
Pilot | |||||||||
---|---|---|---|---|---|---|---|---|---|
For Screw Size | Body Dia. | Head Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
No. 0 | 0.110" | 0.059" | 0.110" | 2 1/2" | 2 | Straight | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |