A Phillips driver has an angle on the flanks, a pointed tip and rounded corners.
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Pozidriv drive bits are often designated by the letters "PZ" plus a size code of 0, 1, 2, 3, 4 or 5 (by order of increasing size) the numerical bit size codes do not necessarily correspond to nominal screw size numbers.Īttempting to use a Phillips screwdriver bit is likely to cause damage because the design difference between them is fairly significant even though at first glance they appear to be very similar. It is very similar to, and essentially compatible with, the Supadriv screw drive.
In ANSI standards, it is referred to as "Type IA". The name is thought to be a portmanteau of the words "positive" and "drive." Its advantage over Phillips drives is its decreased likelihood to cam out, which allows greater torque to be applied. Pozidriv was patented by GKN Screws and Fasteners in 1962.
The Pozidriv (sometimes spelled incorrectly as "Pozidrive") is an improved version of the Phillips screw drive, and is specified as ANSI Type IA Cross Recess. However, a 1949 refinement to the original design described in US Patent #2,474,994 describes this feature. : 85 Extensive evidence is lacking for this specific narrative, and the feature is not mentioned in the original patents. There has long been a popular belief that this was actually a deliberate feature of the design, for the purpose of assembling aluminum aircraft without overtightening the fasteners. The design is often criticized for its tendency to cam out at lower torque levels than other "cross head" designs. Ī Phillips screw head is significantly different from a PoziDriv see § Pozidriv section below for details. Phillips drive bits are often designated by the letters "PH", plus a size code 0000, 000, 00, 0, 1, 2, 3, or 4 (in order of increasing size) the numerical bit size codes do not necessarily correspond to nominal screw size numbers. The Phillips screw design was developed as a direct solution to a number of problems with slotted screws: too-easy cam out precise alignment required to avoid slippage and damage to driver, fastener, and adjacent surfaces and difficulty of driving with powered tools. The American Screw Company of Providence, Rhode Island was responsible for devising a means of efficiently manufacturing the screw, and successfully patented and licensed their method other screw makers of the 1930s dismissed the Phillips concept because it called for a relatively complex recessed socket shape in the head of the screw - as distinct from the simple milled slot of a slotted type screw. The original patent expired in 1966, but the Phillips Screw Company continued to develop improved designs. Phillips is credited with forming a company ( Phillips Screw Company), improving the design, and promoting the adoption of his product. Thompson, who after failing to interest manufacturers, sold his design to businessman Henry F. The Phillips screw drive (specified as an ANSI Type I Cross Recess ) was created by John P. Phillips drive tool and fastener sizes Tool size