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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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 |
| 4 | 7.5 | 1/4" | 0.250" | 5" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 5 | 9 | 5/16" | 0.281" | 5 5/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 6 | 10.5 | 5/16" | 0.313" | 5 5/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 8 | 13.5 | 1/2" | 0.375" | 6 1/2" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 10 | 16.5 | 1/2" | 0.500" | 7" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 12 | 18.5 | 1/2" | 0.500" | 7 1/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 14 | 21.5 | 5/8" | 0.563" | 7 1/2" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 00000 |
| 16 | 24.5 | 5/8" | 0.625" | 7 5/8" | 4 | Spiral | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 000000 |
| 20 | 30.5 | 7/8" | 0.750" | 8 1/8" | 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 |
| 4 | 7.54 | 1/4" | 4.36 | 1 3/8" | 7.54 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 5 | 9.13 | 5/16" | 5.55 | 1 1/2" | 7.94 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 6 | 10.71 | 5/16" | 6.35 | 1 9/16" | 9.52 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 8 | 13.49 | 7/16" | 8.73 | 1 13/16" | 11.11 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 10 | 16.66 | 1/2" | 10.32 | 2 1/16" | 14.29 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 12 | 18.75 | 5/8" | 12.7 | 2 7/16" | 15.87 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 14 | 21.82 | 5/8" | 14.68 | 2 5/8" | 16.67 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 16 | 24.6 | 5/8" | 16.67 | 2 3/4" | 17.46 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
Metric Size Counterbore Sets with Built-In Pilot
The counterbores in this set are oversized for counterboring screw holes in sheets or layers of material that are misaligned. All have a built-in pilot to maintain alignment in the hole.
| Dia. Rating | Sizes Included | Number of Pieces | Pilot Lg. | Number of Flutes | Flute Style | Shank Type | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 0.5 mm Oversized | 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm | 8 | 0.218", 0.250", 0.281", 0.312", 0.375", 0.500", 0.562" | 4 | Spiral | Round | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 0000000 | 0000000 |
Metric Size Drill-Point Counterbore Sets
No need for separate tools, these sets have counterbores in various sizes that drill and counterbore holes with enough clearance for socket head cap screws. The longer the counterbore, the thicker the material it can drill.
Diameter | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sizes Included | Number of Pieces | Body | Shank | Drill Tip | Overall Length | Maximum Hole Drilling Depth | Number of Flutes | Shank Type | For Use On | Container Type | Each | |
Uncoated High-Speed Steel | ||||||||||||
| 3 mm 4 mm 5 mm 6 mm 8 mm 10 mm 12 mm 14 mm 16 mm | 9 | 5.95 mm 7.54 mm 9.13 mm 10.71 mm 13.49 mm 16.66 mm 18.75 mm 21.82 mm 24.6 mm | 1/4" 1/4" 5/16" 5/16" 7/16" 1/2" 5/8" 5/8" 5/8" | 3.57 mm 4.36 mm 5.55 mm 6.35 mm 8.73 mm 10.32 mm 12.7 mm 14.68 mm 16.67 mm | 1 9/32" 1 13/32" 1 9/16" 1 5/8" 1 29/32" 2 5/32" 2 9/16" 2 27/32" 3 1/2" | 6.35 mm 7.54 mm 7.94 mm 9.52 mm 11.11 mm 14.29 mm 15.87 mm 16.67 mm 17.46 mm | 2 | Round | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | Plastic Case | 00000000 | 0000000 |