Editing Screwdriver (section)

===Phillips===
'''Phillips''' screwdrivers come in several standard sizes, ranging from tiny "jeweler's" to those used for automobile frame assembly—or #000 to #4 respectively. This size number is usually stamped onto the shank (shaft) or handle for identification.  Each bit size fits a range of screw sizes, more or less well. Each Phillips screwdriver size also has a related shank diameter.  The driver has a 57° point and tapered, unsharp (rounded) flutes.  The #1 and smaller bits come to a blunt point, but the #2 and above have no point, but rather a nearly squared-off tip, making each size incompatible with the other.

The design is often criticized for its tendency to [[cam out]] at lower torque levels than other "cross head" designs, an effect caused by the tapered profile of the flutes which makes them easier to insert into the screw than other similar styles. There has long been a popular belief that this was actually a ''deliberate'' feature of the design. Evidence is lacking for this specific narrative and the feature is not mentioned in the original patents.<ref>{{cite thesis |degree=Master's |title=Testing and Understanding Screwdriver Bit Wear |date=1998-05-18 |publisher=Virginia Tech |last=Adler |first=Alexander |hdl=10919/36701 |hdl-access=free}}</ref> However, a subsequent refinement to the original design described in US Patent #2,474,994<ref>{{US Patent| 2474994}}</ref><ref>{{Cite patent |inventor-last=Tomalis |inventor-first=Joseph |inventor2-last=American Screw Company |publication-date=December 30, 1942 |issue-date=July 5, 1949 |title=Screw Socket |country-code=US |patent-number=2474994}}</ref><ref>{{cite web |url=http://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey=14D96AF311E8&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2474994.PN.%2526OS%3DPN%2F2474994%2526RS%3DPN%2F2474994 |title=US Patent #2,474,994 Claims, Page 7 |url-status=live |archive-url=https://web.archive.org/web/20170804055028/http://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey=14D96AF311E8&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2474994.PN.%2526OS%3DPN%2F2474994%2526RS%3DPN%2F2474994 |archive-date=2017-08-04 }}</ref> describes this feature.