0-300mm Professional Carpenter Tools Combination Square

Some mechanical measuring tools, such as squares, calipers, etc., were first used in mechanical manufacturing. In the 16th century, smooth gauges were used in artillery manufacture. In 1772 and 1805, British J. Watt and H. Maudsley, etc. successively produced a Watt micrometer and a calibration length measuring machine using the principle of thread pair. After the mid-19th century, measurement tools similar to modern mechanical outer micrometers and vernier calipers appeared successively. At the end of the 19th century, sets of gauge blocks appeared. Following the emergence of mechanical measuring tools is a group of optical measuring tools. At the end of the 19th century, vertical length measuring instruments appeared, and at the beginning of the 20th century, length measuring machines appeared. By the 1920s, projectors, tool microscopes