Drill Bit Decimal Size Equivalents
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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 Drill Bits
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Short-Length Cobalt Steel Drill Bits
Also known as screw-machine and stub-length bits, these provide maximum rigidity for drilling straighter holes than jobbers'-length drill bits. Made of cobalt steel, which has better heat and wear resistance than high-speed steel, they can run up to 25% faster and have a longer tool life.
Titanium-nitride (TiN) coated drill bits last longer and can drill at higher speeds than uncoated drill bits.
Drill bits with a split point keep centered without a pilot hole.
For technical drawings and 3-D models, click on a part number.
Shank | Each | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Drill Bit Size | Decimal Size Equivalent | Overall Lg. | Max. Drilling Dp. | Type | Size | Point Style | For Use On | Each | |
Wire Gauge | |||||||||
Titanium-Nitride (TiN) Coated Cobalt Steel | |||||||||
| 2 ga. | 0.221" | 2 7/16" | 0.88" | Round | 0.221" | Split | Steel, Hardened Steel, Tool Steel, Iron, Stainless Steel, Nickel, Titanium, Fiberglass | 000000000 | 00000 |
| 1 ga. | 0.228" | 2 7/16" | 0.91" | Round | 0.228" | Split | Steel, Hardened Steel, Tool Steel, Iron, Stainless Steel, Nickel, Titanium, Fiberglass | 000000000 | 0000 |
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 | |||||||||
| 12 | 18.75 | 5/8" | 12.7 | 2 7/16" | 15.87 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 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 | |||||||||
1/64" Oversized | |||||||||
| No. 6 | 0.234" | 0.146" | 5/16" | 2 7/16" | 2 | 118° | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
Cobalt Steel Drill/Mill End Mills
Made of cobalt steel, these end mills have good heat and wear resistance, so they can run at high speeds in hard material. A 90° pointed tip allows them to be used for drilling as well as for slotting, profiling, and chamfering cuts. All are center cutting, allowing plunge cuts into a surface.
Use uncoated end mills for general purpose milling and short production runs. Use titanium-nitride (TiN) coated end mills for demanding, high-speed jobs in hard material as well as for longer production runs. They’re more wear resistant than uncoated end mills, which means they last longer when run at similar speeds.
For technical drawings and 3-D models, click on a part number.
| Mill Dia. | Shank Dia. | Lg. of Cut | Overall Lg. | Flute Spacing | Point Angle | Helix Angle | For Use On | End Mill Type | Each | |
Uncoated | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
2 Flute | ||||||||||
| 1/4" | 3/8" | 5/8" | 2 7/16" | Equal | 90° | 30° | Aluminum, Brass, Bronze, Hardened Steel, Iron, Nickel, Plastic, Stainless Steel, Steel, Titanium, Tool Steel | Center Cutting | 0000000 | 000000 |
Titanium Nitride (TiN) Coated | ||||||||||
2 Flute | ||||||||||
| 1/4" | 3/8" | 5/8" | 2 7/16" | Equal | 90° | 30° | Aluminum, Brass, Bronze, Hardened Steel, Iron, Nickel, Plastic, Stainless Steel, Steel, Titanium, Tool Steel | Center Cutting | 0000000 | 00000 |