Robertson vs. Torx
Comparing 2 standards across 10 specifications. 10 key differences identified.
The Robertson drive (Square socket / SCRULOX, standardized under ANSI Type III / CSA B35.4) is a 4-sided tapered square recess drive invented in Canada by P.L. Robertson, patented in 1906-07, with a 1908 manufacturing refinement (cold-forming the socket) that made it commercially viable. Known for its distinct tapered geometry that locks the screw onto the driver bit for one-handed operation, it is the dominant construction and electrical fastener across Canada.
Torx (standardized as Hexalobular Internal under ISO 10664) is a 6-lobed star-shaped screw drive system developed by Camcar Textron in 1967. Engineered with a low 15-degree drive angle and curved lobes, it eliminates cam-out entirely, delivers exceptional torque transfer, and drastically extends tool bit lifespan across automotive, computing, and construction hardware.
Specification Comparison Table
10 Parameters| Parameter / Spec | ||
|---|---|---|
|
Drive Geometry
|
4-sided square recess with a slight interior conical taper (approx. 3° taper) | 6-pointed star with rounded circular lobes |
|
Cam-Out Tendency
|
Near Zero (Straight square drive walls resist climbing) | Zero (Radial drive force completely eliminates axial climb) |
|
Standard Specifications
|
CSA B35.4 / ANSI Type III Square Recess / ASME B18.6.3 | — |
|
Self-Holding 'Stick-Fit'
|
Yes (Taper friction-locks screw onto driver bit for horizontal/overhead 1-handed driving) | — |
|
Color-Coded Sizing System
|
#00 Orange, #0 Yellow, #1 Green, #2 Red (dominant wood/deck size), #3 Black, #4 Brown | — |
|
Primary Geographic Usage
|
Universal in Canada (electrical/framing/decking) / Pocket-hole woodworking globally (Kreg) | — |
|
International Standard
|
— | ISO 10664 (Hexalobular internal driving feature for bolts and screws) |
|
Drive Angle
|
— | 15 degrees (near-perpendicular torque vector) |
|
Common Sizing Tiers
|
— | T1–T5 (smartphones), T6–T10 (laptops/electronics), T15–T25 (wood/auto), T30–T50 (chassis/structural) |
|
External Variant
|
— | E-Torx (Inverted star socket for high-torque automotive bolts, E4 to E24) |