Hamai Co., Ltd was based, originally, at 406, 2-chome, Osakihoncho, Shinagawa-ku near Tokjo in Japan but is now operating from 5-5-15 Nishigotanda Shinagawa-ku in Tokyo. Long a manufacturer of high-precision gear hobbing and gear testing machines, they now specialise in models for the production and testing of small gears for such diverse articles as electric power tools, watches, mechanical instruments, fishing tackle, stepping motors, and electrodes, etc., with, to date in 2024, over 7,000 units sold. Today (2024) the Company manufactures not just gear hobbers, but lapping and polishing machines and duplex millers - the gear hobbers offered during 2024 being the Type GN150 and the Series NS and SP. Lapping and polishing machines are offered from 'bench-top' models to custom-built, giant machines that weigh several tons while duplex milling machines comprise three models, the 2DS-A, 4DS-A and 1DA-A.
From the early 1960s onwards, the gear-testing models 5LD and 6LD were, like many antilog machines of the time, fitted with a system that printed errors on a strip of paper. The print-out was able to show both the pitch error and, with accessory equipment, the run-out. In pitch-error mode, one division of the scale represented a very high standard of precision - to an accuracy of 0.002 mm ( 0.00008").