Responsible for a range of machine tools including engine and turret lathes, radial-arm drills, punch presses, power shears and both vertical and horizontal milling machines the Diamond Tool Company was located at 3428 East Olympic Blvd. Los Angeles in California. So far the only machines to come to light are a range of small horizontal millers, in designs typical of their time and type - though very heavily built and intended for professional rather than amateur work. Models discovered include what is though to have been the largest in the Company's range, the M-24, built on a self-contained underdrive stand with a 1.5 h.p. 3-phase motor powering a variable-speed gearbox combined with a three-speed, fixed-ratio V-belt final drive. To aid rigidity and improve rates of metal removal the end of the arbour was supported by a heavy slotted casting that clamped over the knee V-way. Another version of the M-24 was also offered, the "Extra Heavy Duty" model, equipped with a spindle-speed reduction gearbox, 2 h.p. motor and a 6-section V-belt drive that gave it the ability to run a gang of 8-inch diameter cutters: "without stalling or chattering on toughest of metals"
All models featured a round overarm with the lighter types driven by a simple but strongly-built 3 or 6-speed countershaft fastened to the right-hand face of the main column with the drive on each speed by twin  "B-section belts".  Apart from the "B" range the machines were supplied fitted to a heavy cast-iron stand with a small storage cupboard for accessories and tooling. One unusual option, especially for a smaller miller, was a chain-drive assembly instead of belts on the side-mounted countershaft. This could be either factory installed, or retrofitted by the customer.
A common addition to these sturdy little machines - and many other small horizontal millers of the time - was the mounting of a self-contained vertical head. The better known of these, from the 1930 to 1950s, were the original Bridgeport M,  the "Tree" from Racine, the "Halco" from Detroit and Kearney & Trecker with their Dalrae-manufactured "Midgetmill" and "Speedmill" units.
Machine-tool enthusiasts in California report that the Walt Disney studios bought several new Diamond millers in the early 1950s and installed them in the production shop. Used of