Gauge block
The blocks are joined by a sliding process called wringing, which causes their ultra-flat surfaces to cling together.
A small number of gauge blocks can be used to create accurate lengths within a wide range.
Standard grade blocks are made of a hardened steel alloy, while calibration grade blocks are often made of tungsten carbide (WC), chromium carbide (CrC) or ceramic (SiO2-based) because they are harder and wear less.
[4] 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.
Machinists and toolmakers try to use a stack with the fewest blocks to avoid accumulation of size errors.
As detailed in the Grades section, each block has a size tolerance of a few millionths of an inch, so stacking them together introduces a cumulative uncertainty.
This test is hard to perform on gauge blocks thinner than 0.1 in (2.5 mm) because they tend not to be flat in the relaxed state.
They provide a means of securely clamping large stacks together, along with reference points, scribers, and various shapes of blocks that act like caliper jaws, either external or internal.
A special gauge block stone that cannot damage the surface is used to remove nicks and burrs to maintain wringability.
Various grading standards include: JIS B 7506-1997 (Japan)/DIN 861-1980 (Germany), ASME (US), BS 4311: Part 1: 1993 (UK).
Long series blocks are made from high-quality steel having cross section (35 × 9 mm) with holes for clamping two slips together.
He was concerned with the expensive tools for measuring parts for the Remington rifles then in production under licence at Carl Gustaf.
When Sweden adopted a tailored variant of the Mauser carbine in 1894, Johansson was very excited about the chance to study Mauser's methods of measuring, in preparation for production under license at Carl Gustaf (which began several years later).
On the train home, he thought about the problem, and he came up with the idea of a set of blocks that could be combined to make up any measure.
He preferred to carry out this precision work at home, as the grinding machines at the rifle factory were not good enough.
Once Johansson had demonstrated his set at Carl Gustaf, his employer provided time and resources for him to develop the idea.
[citation needed] The first CEJ gauge block set in America was sold to Henry M. Leland at the Cadillac Automobile Company around 1908.
The first manufacturing plant in America for his gauge block sets was established in Poughkeepsie, Dutchess County, New York, in 1919.
Hounshell (1984), citing Althin (1948) and various archive primary sources, says, "Henry Ford purchased the famous gaugemaking operation of the Swede C. E. Johansson in 1923 and soon moved it into the laboratory facility in Dearborn.
[11] When Johansson started manufacturing gauge blocks in inch sizes in 1912, Johansson's compromise was to manufacture gauge blocks with a nominal size of 25.4mm, with a reference temperature of 20 °C (68 °F), accurate to within a few parts per million of both official definitions.
He was awarded the large gold medal of the Royal Swedish Academy of Engineering Sciences in 1943, shortly after his death.
