There are a variety of measuring instruments kept in a line in the production floor of Cosina’s Nakano factory. They are the kind of things you can expect to find in a machine-shop. The dumbbell-looking tools in the photo above are some of those. They are known as “plug gauges” and are used to measure the inner diameter of cylinders. These gauges are slightly different in diameter at the top and bottom. They demonstrate that the required accuracy has been met when one end fits in a hole and the other one does not. If both ends pass through a hole, the hole is too big, and, if neither does, the hole is too small.
For a manufacturer like us who makes products by assembling cylindrical parts like lens barrels, plug gauges are an absolutely indispensable tool in the production floor.
The dimensional accuracy of threads that have been milled into cylindrical parts is checked using a purpose-specific tool called a “thread gauge.” We keep our thread gauges categorized and divided by diameter, pitch, and right-handed and left-handed threads, in a wooden drawer.
Another tool found almost always next to a machine is called “micrometer.” Micrometers of various types and applications are used in the production floor to measure the dimensions of finished products.
Lots of measurements are done manually, but hi-tech measurements are called in on a daily basis to deal with changes in the prototype design stage, pilot runs of production processes or milling setup. Located in the same building as the production floor, our measurement room is equipped with 3D measuring systems and optical projectors for measuring complicated shapes, instruments for measuring the roughness and variances of metallic surfaces, and other tools for conducting the stringent inspections needed to support machining precision. In manufacturing high-end optical devices, we cannot “make” anything without “measuring” it.