Carl Edvard Johansson

Carl Edvard Johansson (1864–1943) was a Swedish inventor and scientist.

Johansson invented the gauge block set, also known as "Jo Blocks" ("Johansson gauge blocks"). He was granted his first Swedish patent on 2 May 1901, Swedish patent No. 17017 called "Gauge Block Sets for Precision Measurement". He formed the Swedish company CE Johansson AB (CEJ AB), Eskilstuna, Sweden in 1911. The first CEJ gauge block set in America was sold to Henry M. Leland at Cadillac Automobile Co. around 1908.

There are only two people I take off my hat to. One is the president of the United States and the other is Mr. Johansson from Sweden.

— Henry M. Leland, around 1920.

At the end of his career, in 1923, Johansson started to work for Henry Ford at the Ford Motor Company, in Dearborn, Michigan. Ford bought the entire American company, CE Johansson Inc., that he had established 1918 in Poughkeepsie, New York and all the equipment was moved to Dearborn. Some of his Swedish employees that worked in Poughkeepsie were also employed by Ford. At the age of 72, he decided to retire and went back to Sweden. During his life he had crossed the Atlantic Ocean 22 times and spent a lot of time in America.

He received a number of awards and honors, including the large gold medal of the Royal Swedish Academy of Engineering Sciences, posthumously in 1943, shortly after his death.

In the 1910s, the U.S. and U.K. definitions of the inch differed, with the U.S. inch being defined as 25.4000508mm (with a reference temperature of 68 degrees Fahrenheit) and the U.K. inch at 25.399977mm (with a reference temperature of 62 degrees Fahrenheit). When he started manufacturing gauge blocks in inch sizes in 1912, Johnanson's compromise was to manufacture gauge blocks with a nominal size of 25.4mm, with a reference temperature of 20 degrees Celsius, accurate to within a few parts per million of both official definitions. Because Johannson's blocks were so popular, his blocks became the de facto standard for manufacturers in both countries. When the inch was eventually redefined to be exactly 25.4mm in both the U.K. (in 1930) and U.S. (in 1933), this effectively endorsed what was already common practice worldwide.

He was married to Margareta Andersson in 1896. They had four children: Elsa, Signe, Edvard, and Gertrud.