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 | |||||||||
1/64" Oversized | |||||||||
| No. 6 | 0.234" | 0.146" | 5/16" | 2 7/16" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
| No. 8 | 0.281" | 0.175" | 3/8" | 4 1/4" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| No. 10 | 0.328" | 0.206" | 5/8" | 4 5/8" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| No. 10 | 0.344" | 0.206" | 1/2" | 4 3/4" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 1/4" | 0.391" | 0.266" | 1/2" | 5 1/8" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 1/4" | 0.406" | 0.266" | 1/2" | 5 1/4" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 3/8" | 0.578" | 0.391" | 3/4" | 4 1/8" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
1/32" Oversized | |||||||||
| 1/4" | 0.406" | 0.281" | 1/2" | 5 1/4" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 5/16" | 0.500" | 0.344" | 5/8" | 6" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |
| 3/8" | 0.594" | 0.406" | 3/4" | 4 1/8" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 00000 |