Counterbore Drills | McMaster-Carr

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397 Products

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.

Inch Size High-Speed Steel
Counterbores with Built-In Pilot

Metric Size High-Speed Steel
Counterbores with Built-In Pilot

Oversized High-Speed Steel
Counterbores with Built-In Pilot

Counterbore screw holes in misaligned sheets or layers of material.

Oversized Carbide-Tipped
Counterbores with Built-In Pilot for Steel

Designed for counterboring screw holes in misaligned sheets or layers of material.

Carbide-Tipped Counterbores
with Built-In Pilot for Steel

To resist damage when cutting steel, these counterbores are C5 carbide-tipped alloy steel.

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.

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.

High-Speed Steel Changeable-Pilot Counterbores

For general purpose applications.

Carbide-Tipped Changeable-Pilot Counterbores
for Aluminum, Brass, Bronze, and Cast Iron

For excellent performance on abrasive materials such as cast iron and nonferrous metals, these counterbores are C2 carbide-tipped alloy steel.

Carbide-Tipped Changeable-Pilot
Counterbores for Steel

To resist damage when counterboring steel, these counterbores are C5 carbide-tipped alloy steel.

Counterbores for High-Profile
Rounded-Head Screws

Mil. Spec. Counterbores for Hydraulic Ports

Create contoured profiles for installing hydraulic ports in accordance with military and SAE specifications.

Round-Shank Adjustable-Diameter Counterbores

Counterbore multiple diameters with the same tool—use the set screw to adjust the blades to the diameter you need.

Morse Taper-Shank
Adjustable-Diameter Counterbores

This counterbore has a set screw that lets you adjust the blades to counterbore multiple diameters with the same tool.

Tight-Spot Reverse Counterbore Heads

If limited space makes it difficult to counterbore your hole, access it from the other side with one of these tools.

Inch Size Drill-Point Counterbores

Drill and counterbore holes with enough clearance for socket head screws without changing tools.

Metric Size Drill-Point Counterbores

The same tool lets you drill and counterbore holes with enough clearance for socket head screws.

Counterboring Drill Bits

Often called step drill bits.

Oversized Long-Life Counterboring Drill Bits

Often used with screw holes in misaligned sheets or layers of material.

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.

Drill-Bit Counterbores with Drill Bit

These counterbores are attached to a drill bit for drilling and counterboring in a single step.

Drill-Bit Counterbores

For jobbers’ and brad-point drill bits.

Large-Diameter Drill-Bit Counterbores

Also known as multi-spur counterbores, these have two set screws to secure them to a woodworking drill bit.

Counterbore Sets

Inch Size Counterbore Sets with Built-In Pilot

Metric Size Counterbore Sets with Built-In Pilot

Oversized Counterbore Sets with Built-In Pilot

Use these counterbore sets when the screw holes in sheets or layers of material are misaligned.

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.

Inch Size Drill-Point Counterbore Sets

Keep counterbores in various sizes on hand to drill and counterbore holes with enough clearance for socket head cap screws without changing tools.

Drill-Bit Counterbore Sets

Convert standard jobbers’ and brad-point drill bits into counterboring drill bits that drill and counterbore at the same time.

Changeable-Pilot Counterbore Sets

Change out the pilot to use the same tool to counterbore multiple diameters.