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'Henry F. Phillips' (1890 – 1958) was a U.S. businessman from Portland, Oregon, and inventor of the Phillips-head screw and screwdriver. His inventions built on an earlier concept credited to the inventor J. P. Thompson.

Contents

General notes

Selecting the Right Size Tip

Standard Sizes

External links

General notes

The importance of the crosshead screw design is its self-centering properties, useful on automated production lines which use powered screwdrivers. Phillips' major contribution was in driving the crosshead concept forwards to a point where it was adopted by screwmakers and automobile companies.
Although he received patents for the design in 1936 (US Patent #2,046,343, US Patents #2,046,837 to 2,046,840), it was so widely copied that by 1949 Phillips lost his patent.
The American Screw Company was responsible for devising a means of manufacturing the screw, and successfully patented and licensed their method; other screw makers of the 1930s dismissed the Phillips concept since it calls for a relatively complex recessed socket shape in the head of the screw — as distinct from the simple milled slot of a flathead screw.
The Phillips Screw Company and the American Screw Company went on to devise the Pozidriv screw, which differs from the Phillips in that it is designed to accommodate greater torque than the Phillips.

Selecting the Right Size Tip

Using too small a screwdriver for a given Phillips head screw is likely to damage the screw head, and may damage the screw driver as well. The correct size screwdriver is the largest one that fits. If you have a full range of sizes available, start with the size one step larger than you think will fit, and work your way down one size step at a time until you get to the first one that fits in the screw head. But also see the section on different national specifications for size and shape.

Standard Sizes

Japanese Phillips (called "plus driver" in Japan) and American/European Phillips screw heads and screwdriver tips have different engineering specifications that makes the interchange of the two problematic. A letter to the editor in the Winter 2006 issue of Robot magazine points out that many Asian manufacturers have adopted the Japanese Industrial Standard (JIS) for Phillips heads and tips, which has a different shape than the original Phillips design. The JIS standard is designed to not cam-out, while the original Phillips standard has a cruciform-recessed shape that is designed to cam-out.
JIS B 1012:1985
JIS Phillips sizes:

★ 000

★ 00

★ 0

★ 1

★ 2

★ 3
Phillips American sizes:

★ #0

★ #1 (small)

★ #2 (medium--most common)

★ #3 (large)
Phillips metric sizes (according to RadioShack--needs to be cross-referenced with the other sizes):

★ 1.4 mm

★ 1.6 mm

★ 2.0 mm

★ 2.4 mm

★ 2.9 mm

★ 3.8 mm

External links

★ Phillips or Pozidriv? from the Healey Magazine February 1996

★ Not All Screwdrivers are Created Equal from the Winter 2006 issue of Robot Magazine