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Square Bits

Square Bits

Square Bits

Square driver bits (SQ0, SQ1, SQ2, SQ3) engage the Robertson square-drive recess on timber decking screws, treated-pine assembly screws and many heavy-duty self-tappers. Robertson transfers torque across four large flat surfaces - very high torque capacity with minimal cam-out.

Also known as: Robertson Bits, R Bits, SQ Bits, Robertson Drive Bits, Square Drive Bits.

Robertson was patented in 1908 in Canada and remains the dominant drive on Canadian and North American timber construction. In Australia it's standard on decking screws, treated-pine batten screws and structural timber screws. Cam-out resistance under impact-driver use is excellent - the bit stays seated even at high torque.

GRADES AND MATERIALS

Alloy Tool Steel is the standard Square bits material. Heat-treated to a hardness around 60 HRC at the tip for wear resistance, with a slightly softer shank to absorb torsional shock. Most bits are supplied with a bright finish. Alpha (Sheffield Group) bits are the workhorse stock here; Sutton Tools and Hobson Engineering carry equivalent grades.

Alloy Tool Steel, Black Finish is the impact-rated variant - tempering profile tuned for higher fatigue resistance under impact-driver blows. Use these on Square bits that see constant cordless-impact work. Bright-finish bits in an impact driver will snap at the hex shank after 50 to 200 blows.

DRIVE AND INSTALLATION

Insert the bit into a 1/4" hex chuck or a magnetic bit holder. Verify the bit tip matches the fastener recess exactly - undersized bits cam out and strip the recess on the first install. Apply firm axial pressure during driving so the bit stays fully seated. For high-volume work, use power-length bits (50mm+) with a torsion zone to absorb impact-driver hammer blows.

SQ0 fits small fasteners (#6 screws); SQ1 fits #8 to #10 timber screws; SQ2 fits #10 to #12 decking and batten screws (the most-stocked size); SQ3 fits #14 and larger structural timber. Match the bit number to the recess - SQ1 in an SQ2 recess will round out the corners.

A NOTE ON BIT WEAR AND CAM-OUT

Square (Robertson) bits are wear items. Match the bit to the fastener recess exactly, lean into the drive so the bit stays fully seated, and replace bits at the first sign of tip rounding. Cam-out (bit slipping out of the recess under torque) is the failure mode - it strips the fastener recess and wears the bit tip simultaneously. If you're seeing cam-out, the bit is either wrong-size or worn.

SIZING AND LENGTHS

Sized SQ0 to SQ3 by the square-recess corner-to-corner dimension. Length options: 25mm insert, 50mm to 75mm power-length (impact-rated variants common). Square geometry is well-suited to long treated-timber decking screws driven by cordless impact - low cam-out means the bit stays in the screw and the screw drives home without operator fatigue.

WHY AUSTRALIA TRUSTS BOLT & NUT

With 15+ years selling fasteners and tooling online from Brisbane, we hold over 25,000 stock lines and 200 million pieces - 98.75% of online orders placed before 1pm leave same day. Save more as you buy more - we offer up to 13 price breaks plus 3 spend-tier discounts. Read our customer reviews or get in touch if you need help picking the right Square driver bit.

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