Editing Screwdriver (section)

=== Robertson ===
{{See also|Robertson screw}}
[[File:Robertson screwdrivers.jpg|thumb|A variety of Robertson sizes]]
'''Robertson''', also known as a '''square''',<ref>{{cite book |url=https://books.google.com/books?id=qWYVk7lSsN4C&pg=PA107 |title=Furniture Projects for the Deck and Lawn |publisher=Cambium Press |date=2004 |access-date=2012-03-12 |isbn=978-1-892836-17-5 |url-status=live |archive-url=https://web.archive.org/web/20131011223753/http://books.google.com/books?id=qWYVk7lSsN4C&pg=PA107 |archive-date=2013-10-11 }}</ref> or '''Scrulox'''<ref>{{cite web |last=Robertson Inc. |title=Robertson Inc. - The Original Robertson Fastening System |url=http://www.robertsonscrew.com/ |work=Robertson Inc. main site |access-date=2011-09-28 |url-status=live |archive-url=https://web.archive.org/web/20110926201148/http://www.robertsonscrew.com/ |archive-date=2011-09-26 }}</ref>  screw drive has a [[Square (geometry)|square]]-shaped socket in the screw head and a square protrusion on the tool. Both the tool and the socket have a taper, which makes inserting the tool easier, and also tends to help keep the screw on the tool tip. (The taper's earliest reason for being was to make the manufacture of the screws practical using [[cold forming]] of the heads,<ref name="Rybczynski2000pp79-81">{{Harvnb|Rybczynski|2000|pp=79–81}}.</ref> but its other advantages helped popularize the drive.) Robertson screws are commonplace in [[Canada]], though they have been used elsewhere,<ref name="Rybczynski2000pp85-86">{{Harvnb|Rybczynski|2000|pp=85–86}}</ref> and have become much more common in other countries in recent decades. Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken.<ref name="Rybczynski2000pp85-86" /> They also allow for the use of angled screw drivers and trim head screws. The socket-headed Robertson screws are self-centering, reduce cam out, stop a power tool when set, and can be removed if painted over or old and rusty.<ref name="Rybczynski2000pp85-86" /> In industry, they speed up production and reduce product damage.  One of their first major industrial uses was the Ford Motor Company's Model A & Model T production.  Henry Ford found them highly reliable and saved considerable production time, but he could not secure licensing for them in the United States, so he limited their use solely to his Canadian division. Robertson-head screwdrivers are available in a standard range of tip sizes, from 1.77mm to 4.85mm.