GarageTypes of Screwdrivers: How to Tell a Robertson Driver From a Phillips

Types of Screwdrivers: How to Tell a Robertson Driver From a Phillips

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As the story goes, one day in the early 1900s a young Canadian salesman by the name of Peter Lymburner (P.L.) Robertson was setting up his sales stall when the slot-headed screwdriver he was using slipped and gashed his hand. Robertson’s painful accident lead to a bolt of inspiration and woodworkers – particularly those north of the U.S.-Canada border – have been thanking his misfortune every since.

Square pegs: The Robertson driver

After a series of trials-and-errors, Robertson came up with a method for manufacturing screw heads with a recessed square slot (and corresponding screwdrivers) that would prevent “cam out,” the term for when a driver slips out of the screw it’s turning. Today, users can buy Robertson drivers with yellow, green, red, and black colour-coded handles that fit specific sized screw heads. If you fit the right Robertson screw onto its appropriate driver (a #8 screw in a red-handled driver, for example) you can hold the screw horizontally without fear of it slipping out. Try that with a slot-head screw.

Although P.L. Robertson’s patent has long since expired, the company he founded still bears his name and will celebrate its 110th anniversary in 2018.

While the Robertson screw has been used and endorsed by everyone from New Yankee Workshop host Norm Abram and the Ford Motor Company, and a set – or three – can be found in virtually every Canadian’s toolbox, the Robertson screw is relatively unknown outside of woodworking circles in the States.

Star struck: The Phillips driver

U.S. readers are likely more familiar with the star-patterned Phillips-head screw. After all, it was an American businessman named Henry Phillips (with two Ls) who invented his eponymous driver in the 1930s. Like Robertson’s design, the Phillips screw resists cam out – though not as effectively – and with a properly sized bit you can hold a screw on the end of a driver vertically. The downside is that many cheap Phillips screws are made with inferior materials that easily strip.

In case you need a memory device to help tell the Robertson and Phillips screws apart, here’s a self-deprecating one: You can think of Canadians like Mr. Robertson as, ahem, a bit “square,” while Yankees such as Mr. Phillips are the real “stars” of global commerce.

Wedge Edge: Making slot drivers work

Unfortunately, due to simple design (and, therefore, cheaper construction) slot-head screws remain popular in everything from children’s toys to light switch cover plates. (Certainly many of us must have several switch plates with gouge marks from when the driver slipped while removing them to paint a room.)

Since they won’t go away, inventors have tinkered with different ways to make them slip-resistant. The latest, the Quick-Wedge, has a two-piece head. A sliding piece on the handle forces the two halves apart, locking a slot-screw in place. As a result, as with the other two, you can hold a screw horizontal and are less likely to experience cam out.


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