Phillips vs. Robertson
Comparing 2 standards across 10 specifications. 10 key differences identified.
The Phillips drive (Type I cross recess) is a self-centering cruciform drive system invented by John P. Thompson and commercialized by Henry F. Phillips in the 1930s (ANSI Type I / ISO 4757). Engineered with curved flutes and intentional cam-out torque limiting, it revolutionized high-speed automotive and aircraft assembly.
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 (Cross recesses) / ANSI Type I / DIN 7962 | CSA B35.4 / ANSI Type III Square Recess / ASME B18.6.3 |
|
Drive Geometry
|
Cruciform 4-wing cross with rounded corners and 57° tapered flanks | 4-sided square recess with a slight interior conical taper (approx. 3° taper) |
|
Self-Centering Capability
|
Yes (Driver tip automatically centers into recess) | — |
|
Intentional Cam-Out
|
Yes (Designed to cam-out when tightened to prevent over-torquing and thread stripping) | — |
|
Common Sizing Tiers
|
PH000, PH00, PH0, PH1, PH2 (most common), PH3, PH4 | — |
|
Common Screw Pairings
|
Drywall screws, PC cases (#6-32), general wood and machine screws | — |
|
Self-Holding 'Stick-Fit'
|
— | Yes (Taper friction-locks screw onto driver bit for horizontal/overhead 1-handed driving) |
|
Cam-Out Tendency
|
— | Near Zero (Straight square drive walls resist climbing) |
|
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) |