In the dimensional metrology field, gage blocks are the universally used physical standards to which most linear dimensions are compared directly or indirectly. Prior to their existence, gage ‘sticks’ were used, each one being made to a specific dimension but the cost over time and their storage made them costly artifacts to use.
Carl Johansson of Sweden realized these problems and developed a series of sizes that could be combined to form a near endless number of dimensions. Once a dimension was no longer needed, the pieces used to create it could be used in other combinations or ‘build-ups’—a considerable cost saving.
Keeping the blocks in a build-up together was critical to ensure the accuracy of the required dimension as was making them to very precise dimensions. Johansson solved these problems by turning his wife’s sewing machine into a device that could be used to lap the precision faces of the blocks to precise dimensions while keeping them flat and parallel. This enabled those faces to be brought into intimate contact through the process we know as ‘wringing’ so they stuck together with little or no change in the overall dimension required.