Pozidriv vs. Robertson
Comparing 2 standards across 10 specifications. 10 key differences identified.
The Pozidriv drive (ANSI Type IA cross recess / ISO 4757) is an improved cruciform drive developed by GKN Screws and Fasteners in 1962. Identified by four secondary radial score lines etched at 45 degrees between the main cross blades, it features parallel, non-tapered sidewalls that eliminate cam-out and allow significantly higher torque transmission than Phillips.
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.
Specification Comparison Table
10 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 4757 Type IA / BS 3529 / DIN 7962 | CSA B35.4 / ANSI Type III Square Recess / ASME B18.6.3 |
|
Cam-Out Tendency
|
Extremely Low (Does not push driver out under high torque) | Near Zero (Straight square drive walls resist climbing) |
|
Visual Identification
|
4 distinctive radial tick marks embossed at 45° between the main cross arms | — |
|
Flank Geometry
|
Parallel vertical sidewalls (zero taper angle, unlike Phillips 57° taper) | — |
|
Standard Sizing Tiers
|
PZ0, PZ1, PZ2 (dominant European carpentry size), PZ3, PZ4 | — |
|
Primary Geographical Usage
|
Dominant across European construction, cabinetry (IKEA furniture), and automotive | — |
|
Drive Geometry
|
— | 4-sided square recess with a slight interior conical taper (approx. 3° taper) |
|
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) |