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 Vibration-Resistant
Through-Hole Countersinks with Pilot for Screws
The built-in pilot maintains alignment in the hole. Also known as zero-flute countersinks, these have an angled hole that passes through the center of the tool to reduce vibration and chatter, which creates smooth cuts and prevents chips from clogging the countersink. The 82° countersink angle is compatible with the profile of flat- and oval-head inch screws.
For technical drawings and 3-D models, click on a part number.
Pilot | 82° Countersink Angle | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Hole Dia. | For Screw Size  | Body Dia. | Shank Dia. | Dia. | Lg. | Overall Lg. | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
0 Flute | |||||||||
| 5/16" to 41/64" | 5/16" | 41/64" | 3/8" | 5/16" | 5/32" | 2 3/16" | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
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. | 82° Countersink Angle | ||||||
|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Drill Tip | Overall Lg. | For Use On | Each | |
Uncoated High-Speed Steel | |||||||
2 Flute | |||||||
| 5/16" | 5/8" | 3/8" | 0.315" | 2 5/8" | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
Countersinking Drill Bits for Screws
Also known as step drill bits, these bits countersink as they drill. The 82° countersink angle is compatible with the profile of flat- and oval-head inch screws. After multiple sharpenings, the drill bit diameter may become smaller.
For technical drawings and 3-D models, click on a part number.
Dia. | Lg. | 82° Countersink Angle | |||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Step | Step | Overall | Shank Dia. | Point Angle | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
2 Flute | |||||||||
| 5/16" | 0.625" | 0.320" | 3/4" | 7 1/8" | 0.6250" | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
High-Speed Steel Drill-Point Countersink Sets for Screws
Small drill points let you drill and countersink holes with the same tool. The 82° countersink angle is compatible with the profile of flat- and oval-head inch screws.
For technical drawings and 3-D models, click on a part number.
82° Countersink Angle | ||||||||
|---|---|---|---|---|---|---|---|---|
| For Screw Size | Number of Pieces | Number of Flutes | Number of Countersinking Ends | Shank Type | For Use On | Container Type | Each | |
Uncoated High-Speed Steel | ||||||||
| No. 5, No. 6, No. 8, No. 10, No. 12, 1/4", 5/16", 3/8" | 8 | 2 | 1 | Round | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | Plastic Case | 00000000 | 0000000 |
Inch Size High-Speed Steel Counterbores with Built-In Pilot
The built-in pilot maintains alignment in the hole.
Titanium nitride (TiN) coated counterbores are more wear and heat resistant than uncoated counterbores.
For technical drawings and 3-D models, click on a part number.
Dia. | Pilot | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated High-Speed Steel | ||||||||||
| 5/16" | 0.475" | 3/8" | 5/16" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
Titanium Nitride (TiN) Coated High-Speed Steel | ||||||||||
| 5/16" | 0.475" | 3/8" | 5/16" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
Oversized High-Speed Steel Counterbores with Built-In Pilot
Use these oversized counterbores when the screw holes in sheets or layers of material are misaligned. The built-in pilot maintains alignment in the hole. The body diameter and pilot diameter account for the 1/32” or 1/64” oversized diameter rating.
Titanium nitride (TiN) coated counterbores are more wear and heat resistant than uncoated counterbores.
For technical drawings and 3-D models, click on a part number.
Dia. | Pilot | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated High-Speed Steel | ||||||||||
1/64" Oversized | ||||||||||
| 5/16" | 0.491" | 3/8" | 0.328" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
1/32" Oversized | ||||||||||
| 5/16" | 0.506" | 3/8" | 0.344" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
Titanium Nitride (TiN) Coated High-Speed Steel | ||||||||||
1/64" Oversized | ||||||||||
| 5/16" | 0.491" | 3/8" | 0.328" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
1/32" Oversized | ||||||||||
| 5/16" | 0.506" | 3/8" | 0.344" | 0.375" | 6 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
Carbide-Tipped Counterbores with Built-In Pilot for Steel
To resist damage when cutting steel, these counterbores are C5 carbide-tipped alloy steel. The built-in pilot maintains alignment in the hole.
For technical drawings and 3-D models, click on a part number.
Dia. | Pilot | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated C5 Carbide-Tipped Alloy Steel | ||||||||||
| 5/16" | 0.475" | 3/8" | 5/16" | 0.375" | 6 1/8" | 3 | Spiral | Steel | 00000000 | 0000000 |
Oversized Carbide-Tipped Counterbores with Built-In Pilot for Steel
Counterbore screw holes in misaligned sheets or layers of material. These counterbores are C5 carbide-tipped alloy steel to resist damage when used with steel. They have a built-in pilot to maintain alignment in the hole. The body diameter and pilot diameter account for the 1/32” or 1/64” oversized diameter rating.
For technical drawings and 3-D models, click on a part number.
Carbide-Tipped Counterbores with Built-In Pilot
for Aluminum, Brass, Bronze, and Cast Iron
C2 carbide-tipped alloy steel has excellent performance on abrasive materials such as cast iron and nonferrous metals. The built-in pilot maintains alignment in the hole.
For technical drawings and 3-D models, click on a part number.
Dia. | Pilot | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated C2 Carbide-Tipped Alloy Steel | ||||||||||
| 5/16" | 0.475" | 3/8" | 5/16" | 0.375" | 6 1/8" | 3 | Spiral | Aluminum, Brass, Bronze, Cast Iron | 00000000 | 0000000 |
Oversized Carbide-Tipped Counterbores with Built-In
Pilot for Aluminum, Brass, Bronze, and Cast Iron
Use these counterbores with screw holes in misaligned sheets or layers of material. They are C2 carbide-tipped alloy steel for excellent performance on abrasive materials such as cast iron and nonferrous metals. The built-in pilot maintains alignment in the hole. The body diameter and pilot diameter account for the 1/32” or 1/64” oversized diameter rating.
For technical drawings and 3-D models, click on a part number.
Dia. | Pilot | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Dia. | Lg. | Overall Lg. | Number of Flutes | Flute Style | For Use On | Each | |
Uncoated C2 Carbide-Tipped Alloy Steel | ||||||||||
1/64" Oversized | ||||||||||
| 5/16" | 0.491" | 3/8" | 21/64" | 0.375" | 6 1/8" | 3 | Spiral | Aluminum, Brass, Bronze, Cast Iron | 00000000 | 0000000 |
1/32" Oversized | ||||||||||
| 5/16" | 0.506" | 3/8" | 11/32" | 0.375" | 6 1/8" | 3 | Spiral | Aluminum, Brass, Bronze, Cast Iron | 00000000 | 000000 |
Inch Size Drill-Point Counterbores
Drill and counterbore holes with enough clearance for socket head screws without changing tools. The longer the counterbore, the thicker the material it can drill.
For technical drawings and 3-D models, click on a part number.
Dia. | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Shank | Drill Tip | Overall Lg. | Max. Hole Drilling Dp. | Number of Flutes | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
| 5/16" | 0.490" | 1/2" | 0.34" | 1 15/16" | 0.375" | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
| 5/16" | 0.490" | 1/2" | 0.34" | 3" | 1.02" | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 000000000 | 00000 |
Counterboring Drill Bits
Often called step drill bits, these drill and counterbore holes at the same time. After drilling and counterboring, tap the hole and install your fastener. The body diameter may decrease after multiple sharpenings.
For technical drawings and 3-D models, click on a part number.
Dia. | Lg. | |||||||
|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Step | Step | Overall | Point Angle | For Use On | Each | |
Uncoated High-Speed Steel | ||||||||
| 5/16" | 0.500" | 0.344" | 3/4" | 6" | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
Oversized Long-Life Counterboring Drill Bits
These counterbores are often used when screw holes in sheets or layers are misaligned. Also known as subland drill bits, they last longer than standard counterboring drill bits because the diameter stays the same after sharpening. They drill and counterbore at the same time. After drilling and counterboring, tap the hole and install your fastener. The diameters account for the 1/32” or 1/64” oversized diameter rating.
For technical drawings and 3-D models, click on a part number.
Dia. | Lg. | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Step | Step | Overall | Number of Flutes | Point Angle | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
1/32" Oversized | |||||||||
| 5/16" | 0.500" | 0.344" | 5/8" | 6" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
Long-Life Counterboring Drill Bits
Also known as subland drill bits, these last longer than standard counterboring drill bits because the diameter stays the same after sharpening. They drill and counterbore at the same time. After drilling and counterboring, tap the hole and install your fastener.
For technical drawings and 3-D models, click on a part number.
Dia. | Lg. | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| For Screw Size | Body | Step | Step | Overall | Number of Flutes | Point Angle | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
| 5/16" | 0.469" | 0.313" | 5/8" | 3 5/8" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |