About Counterbores
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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About Countersinks
Countersinks cut a cone-shaped opening to install screws and rivets flush with a surface or hold workpieces between centers on a lathe. They can also be used for chamfering and deburring.
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High-Speed Steel Drill-Point Countersinks for Screws
A small drill point at the tip lets you use the same tool for drilling and countersinking holes. An 82° countersink angle is compatible with the profile of flat- and oval-head inch screws; a 90° countersink angle is compatible with the profile of flat- and oval-head metric screws and is also good for deburring.
For technical drawings and 3-D models, click on a part number.
Dia. | 90° Countersink Angle | ||||||
|---|---|---|---|---|---|---|---|
| For Screw Size  | Body | Shank | Drill Tip | Overall Lg. | For Use On | Each | |
Uncoated High-Speed Steel | |||||||
2 Flute | |||||||
| 3 mm | 6.350mm | 6.35mm | 3.100mm | 44.44mm | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
Metric Size High-Speed Steel Counterbores with Built-In Pilot
These counterbores are oversized for use with screw holes in misaligned sheets or layers of material. All have a built-in pilot to maintain alignment in the hole. The body diameter and pilot diameter account for the 0.5 mm oversized diameter rating.
For technical drawings and 3-D models, click on a part number.
Dia. | Lg. | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size, mm | Body, mm | Shank | Pilot | Overall | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
0.5 mm Oversized | |||||||||
| 3 | 6 | 3/16" | 0.219" | 4 1/2" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
Metric Size Drill-Point Counterbores
The same tool lets you drill and counterbore holes with enough clearance for socket head screws.
For technical drawings and 3-D models, click on a part number.
Dia. | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size, mm | Body, mm | Shank | Drill Tip, mm | Overall Lg. | Maximum Hole Drilling Depth, mm | Number of Flutes | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
| 3 | 5.95 | 1/4" | 3.57 | 1 1/4" | 6.35 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |