More recent grade designations include (U.S. Federal Specification GGG-G-15C):
and ANSI/ASME B89.1.9M, which defines both absolute deviations from nominal dimensions and parallelism limits as criteria for grade determination. Generally, grades are equivalent to former U.S. Federal grades as follows:
The ANSI/ASME standard follows a similar philosophy as set forth in ISO 3650. See the NIST reference below for more detailed information on tolerances for each grade and block size.
Back home Johansson converted his wife's sewing machine (a Singer machine) to a grinding and lapping machine, he preferred to carry out this precision work at home as the grinding machines at the Rifle factory were not good enough. His wife Margareta helped him a lot with the grinding beside the household works. Once Johansson had demonstrated his set at Carl Gustaf his employer provided time and resources for him to develop the idea. Johansson was granted his first Swedish patent on 2 May 1901, SE patent No. 17017 called "Gauge Block Sets for Precision Measurement". Johansson formed the Swedish company CE Johansson AB (also known as 'CEJ') on 16 March 1917.
Johansson spent many years in America, during his life he crossed the Atlantic 22 times. The first CEJ gauge block set in America was sold to Henry Martin Leland at Cadillac Automobile Co. around 1908. The first manufacturing plant in America for his gauge block sets was established in Poughkeepsie, Dutchess County, New York in 1919. The economy did not turn out so well for the company so in 1923 he wrote a letter to Henry Ford, at the Ford Motor Company, where he proposed a cooperation in order to save his company. Henry Ford became interested, and on 18 November 1923 he began working for Henry Ford in Dearborn, Michigan. He stayed for 12 years at Ford. At the age of 72, in 1936, he felt it was time to retire and go back to Sweden. He was awarded the large gold medal of the Royal Swedish Academy of Engineering Sciences, posthumously in 1943, shortly after his death.
Shown at right is an image of a metric gauge block set; close examination of the set will show that the set consists of a range of varying size blocks, along with two wear blocks.
In use, the blocks are removed from the set, cleaned of their protective coating (petroleum jelly or oil) and wrung together to form a stack of the required dimension, with the minimum number of blocks. The wear pieces are included at each end of the stack whenever possible as they provide protection against damage to the lapped faces of the main pieces. After use the blocks are reoiled or greased to protect their faces from corrosion.
Wringing is the process of sliding the two blocks together so that their faces lightly bond. When combined with a very light film of oil, this action excludes any air from the gap between the two blocks. The alignment of the ultra-smooth surfaces in this manner permits molecular attraction to occur between the blocks, and forms a very strong bond between the blocks along with no discernible alteration to the stack's overall dimensions.
The pictured accessories provides a set of holders and tools to extend the usefulness of the gauge block set. They provide a means of securely clamping large stacks together along with reference points and scribers.
Slip gauges are made from a select grade of carbide with hardness of 1500 Vickers hardness. Long series slip gauges are made from high quality steel having cross section (35 x 9 mm) with holes for clamping two slips together.