Tuesday, August 30, 2011

Origins: Phillips Head screw


Ever wondered why a Phillips Head screw is called that?  I was pondering this when my son left a Phillips Head screwdriver on my study desk after doing something mechanical.  I readily confess that I am a mechanical idiot and that I have no knowledge of cars, engines and the like, nor do I have any wish to know.  I am nonetheless intrigued by the origin of things…

The Phillips Head screw . . .

With the drive to mass production of cars in the 1920’s, the traditional slotted screw was proving inadequate.  The assembly line relied upon automated processes.  A driver slipping out of a screw slot slowed down production; a damaged screw head as a result was even worse, necessitating removal of the screw.  The Phillips head screw allowed self centering of the driver, uniform torque and better automated procedure.

It had first been developed by an Oregon inventor named J.P. Thompson, who had received a patent in 1933 for a cruciform-recessed screw.  He was unable to interest screw manufacturers in that they believed that the punch needed to create the + recess would destroy the screw head.  Discouraged and of the belief that the screw could not be manufactured, he discussed the matter with his friend Henry Phillips, who bought the patent from him. 

Phillips, an engineer, formed the Phillips Screw Company and made some modifications to the design.  In 1934 he began revisiting many of the same manufacturers that had rejected Thompson, including the biggest US screw manufacturer, the wonderfully named American Screw.  (You seriously didn’t expect this item to not have at least one risque reference, did you?).  The new President of American Screw, Eugene Clark, ignored the protests of his engineers and supported its development.  He later commented “I finally told my head men that I would put on pension all who insisted it could not be done”

General Motors started using the system in its 1937 Cadillacs and by 1940, 85% of the screw manufacturing companies had a license to produce the Phillips screw recess design. Almost the entire automotive industry had shifted to using it.  Usage continued during WW2 of the Phillips screw on many wartime products and vehicles.

Phillips retired in 1945 by reason of ill health and he died in 1958.

The original patents expired in 1996 and the design is now generic.  The Phillips Screw Company and the American Screw Company have gone on  to devise the Pozidriv screw, which has a design more appropriate to modern electrical screwdrivers than the Phillips`.

Having commenced this item with a reference to a screwdriver, I will also conclude with one.

Julia Gillard was being driven back to Canberra from Sydney by her driver late at night when the car in which she was being driven sustained a flat tyre.  Unfortunately for the driver, someone had taken the tyre iron from the boot.  Try as he might, he was unable to remove the hubcap with his hands. 

After some time, Julia Gillard leant her head out of the window and said “Do you need a screwdriver?” 

“Might as well,” replied the driver, “I’m not getting anywhere with this bloody hubcap.”


  1. Although many people refer to any screw head that has cross-shaped grooves as a Phillips head, there are other types of screws that have similar slots. A cross head features two full-length slots that cross, which allows a flat-head screwdriver to be used and makes the screw usable even if one slot has been worn away.

  2. John P Thompson held the original patent.

    Tim Miltz

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  4. Grab a screwdriver in either a safety grip or a neutral one and hold it in front of the screwdriver, then use your thumb and index finger to push the screw outward until it's no longer available. Source to know about how to remove a stripped screw.


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