A form of screwdriver with a square head. The primary advantage of the Robertson screwdriver is that the square head fits snugly inside the screw, and resists the screw falling off.

The screwdriver was invented by Canadian Inventor Peter Lymburner Robertson around the turn of the century, as a replacement for the flathead screwdriver. He patented the system in 1908, which was soon used in the construction of the Ford Model T car line. Robertson screwdrivers are color coded: green, red and black -- for different sizes of screws.

In Canada, over 85% of screws sold have the Robertson head. In the United States, Robertson screws comprise about 10% of screw sales.

I live in Canada. My dad is religious about the Robertson screw. So much so that I've seen him bring an item home from the store, systematically remove all of the slot and/or Phillips screws from it and throw them away, and replace them all with the Robertson screw.

When I left home for University, my mom gave me sheets and towels and stuff. My dad gave me three baby food jars, each full of a different sized Robertson screw, and a set of those colour coded screwdrivers.

I still have both the screwdrivers and the jars. I've used most of the screws, replacing weak or stripped ones. And I discovered the method behind the madness. Whenever I have to take something apart, I have to find both the right sized Robertson screwdriver and whatever type the original screws were. He only needs one.

Smart man, my dad.

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