Snake Eye Bits

Snake Eye security driver bits are two-pin spanner-style bits that engage two cross-bored holes in a snake-eye security fastener. Used on coin-locked enclosure covers, public-area tamper-evident panels and security-rated electrical fittings.

Also known as: Spanner Bits, Two-Hole Spanner Bits, Pig Nose Bits, Snake Eye Drive Bits, Drilled Spanner Bits.

The two pins on the bit tip engage two cross-drilled holes in the screw face. Pin diameter and spacing are critical - the bit must match the fastener exactly or the pins won't seat. Snake Eye is a low-torque drive system; do not use it as a structural fastener drive.

GRADES AND MATERIALS

Alloy Tool Steel is the standard Snake Eye security 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 Snake Eye security 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.

Chuck the bit into a 1/4" hex driver. Align the two bit pins with the two holes on the screw face. Apply firm axial pressure as you start to rotate. The pins must seat fully in the screw holes or the bit will slip and damage both. Stocked sizes match Hobson Engineering security fastener spec.

A NOTE ON BIT WEAR AND CAM-OUT

Snake Eye security 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 by pin diameter and pin-to-pin distance, matched to the snake-eye fastener spec. Stocked sizes are #4 through #8 equivalent. Length 25mm insert is the standard format.

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