Square Insert Bits

Square Insert Bits

Shop a variety of square insert bits, or Robertson bits, to complete your project the right way. 

Square Bits (Robertson / Square Drive Insert Bits)

Square bits, also called square drive bits or Robertson bits, are engineered for high-torque fastening with minimal cam-out. These square bits for drills fit standard 1/4" hex chucks and are available as both compact insert bits and extended square power bits, giving you reliable performance across woodworking, metal fastening, cabinetry, framing, decking, trailer construction, and equipment assembly.

Our square insert bits are designed to create a secure, consistent fit inside every fastener head. Whether you are running a drill, impact driver, mortising machine, or drill press, these bits hold firm under pressure. 

They are cold-forged from heavy-duty, high-grade steel and feature a built-in torsion zone that absorbs torque spikes, resulting in long life during high-torque fastening applications in both metal and wood.

Insert Bits vs Power Bits

Square insert bits are short 1" bits designed to be used with a bit holder. Their compact size makes them ideal for tight spaces, assembly work, and repetitive use where you need quick bit changes. These are the most common formats for #1, #2, and #3 square bits.

Square power bits, by contrast, are longer (typically 2" to 6") and designed for direct insertion into your drill or impact driver. Their extended length helps you reach recessed fasteners, clear obstructions, and maintain better alignment over longer distances. When choosing between insert bits and power bits, select the length required by your workspace and the reach of the fastener pocket.

Choosing the Right Square Bit Size (#1, #2, #3)

Square bits are available in standardized Robertson bit sizes designed to match square drive screws.

#1 square bit

Used for small screws and light-duty fastening, often seen in hardware, fixtures, and delicate installations.

#2 square bit

The most common size for construction, woodworking, decking, cabinetry, and general-purpose fastening.

#3 square bit

Designed for heavy-duty structural screws, lag screws, large decking fasteners, and demanding outdoor or framing applications.

All sizes in this collection use a universal 1/4" hex shank compatible with drills and impact drivers.

High-Quality Square Insert Bits from Benchmark Abrasives

Square bits are used when you need a stronger hold, less cam-out, and stable engagement under high torque. They excel in structural fastening, outdoor building projects, cabinet installation, decking, framing, and any application where fastener stripping is a concern. 

When paired with a standard drill or impact driver, a square driver bit or square drill bit provides consistent performance even in demanding conditions. Our products are made from quality materials and are durable for any project.