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Dumb Nail Chisel

Video: Dumb Nail Chisel
Video: The worst toenail on earth! “Thorn" inside the toe - 2023, February
Dumb Nail Chisel
Dumb Nail Chisel

And the screwdriver assembly of everything and everything - from bookshelves to cars - has not surprised anyone for a long time. Meanwhile, according to the official version, a screwdriver was invented relatively recently - in the 17th century. But, most likely, this happened at least a century earlier, when the rapid flourishing of precision mechanics began. As at all times, the arms race, in particular, the evolution of small arms, became the locomotive of progress: by the 15th century, smaller copies of conventional guns were replaced by arquebus and musket, and in the 16th century, wheeled and shock flintlocks appeared. The pistols of that era already have fixing and adjusting screws with a slotted slot. A completely modern self-tapping screw is depicted in one of the drawings in the book of George Agricola "On metals" (De Re Metallica), which saw the light in 1556. It is hard to imagine that medieval craftsmen sawed the slot on the screws for the sake of beauty and only their descendants guessed to insert a screwdriver into it.

The "tool in the form of a blunt chisel, " as Dahl's screwdriver defines, lasted almost unchanged until the beginning of the 20th century, when Canadian salesman Peter Robertson proposed a new profile for its working part. The impetus for the invention was the injury: during the next demonstration of a spring-loaded slotted screwdriver, its blade popped out of the slot on the screw and stuck into Robertson's hand. In 1907, he patented a screw with a central groove, which immediately interested industrialists. Note that before, starting in 1860, there were many proposals to improve the screw head, but all of them turned out to be too complicated for mass production. The Robertson screw was relatively cheap to manufacture and had many advantages. The screwdriver was perfectly centered in the square recess of the cap (the spread in the size of the groove did not exceed a thousandth of an inch), it was possible to work almost by touch, at a slight angle, and, most importantly, to transmit considerable effort.

The novelty came in handy at the Ford factories: in the T model there were more than 700 such screws (including the wooden bodies of the Canadian company Fisher Body), they also took root at the Ford A. Robertson’s plant in Milton (Ontario) was operating at full capacity, but disagreements with local financial tycoons prevented the establishment of full-fledged production in the United States.

In 1936, another entrepreneurial salesman, an American Henry Phillips from Portland in Oregon, patented his propeller version and launched production. The Philips screw was liked by General Motors technologists, and in the same year they began to use it in the assembly of Cadillacs. A number of shortcomings in comparison with the “Canadian square” (less transmitted force, the tendency to slip a screwdriver) did not prevent the “American cross” during World War II from becoming a de facto national standard. Soon he reached Russia, but in a very peculiar way. In the late 40s, these screws were copied from American long-range B-29 bombers captured in Manchuria and Eastern Siberia. So the Soviet Tu-4 with overseas fasteners was born.

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