Your article “Choose the Right Screw for Today’s Job” praised the square-drive screw as a modern replacement for slip-prone slotted- and Phillips-head screws. Aren’t those the same Robertson screws?


Your article "Choose the Right Screw for Today's Job" (July 2009, Issue 191) praised the square-drive screw as a modern replacement for slip-prone, slotted- and Phillips-head screws. But aren't those the same Robertson screws that we Canucks have been using for more than a century?
—Jay Owens, Edmonton, Alta.


You're correct, Jay. The Robertson, or square-drive screw, which only recently gained acceptance in the United States, has been favored in Canada for decades. Inventor Peter Lymburner Robertson came up with the idea in 1908 after cutting his hand with a slotted screwdriver.

The head features a slightly tapered square socket making it self-centering, easier to drive one-handed, and slip-resistant. Because it sped up production with less chance of product damage, the manufacturing sector loved it, making Robertson's screw an instant hit.

Most historians attribute its lack of popularity in the United States to Henry Ford. Having been nearly bankrupted by shady European licensees, Robertson refused to license his invention to Ford. Without a guaranteed supply, Ford turned to the Phillips-head screw, cementing its reign in American industry.

The company that Robertson created to produce the screws and screwdrivers (Robertson Inc.) remains in business today, with its headquarters in Milton, Ontario, where it was founded.

In 2007, the Canadian Broadcasting Company placed the Robertson as #7 on its list of the 50 greatest Canadian inventions, directly behind #6, the pacemaker, and #5, the Wonderbra. Oh, Canada!

A drawing from the original patent form for the Robertson screw illustrates the slight taper of the square head and the proposed mating screwdriver.