In 1941, the Army and Navy Munitions Board asked Louis Levin if he would be willing and able to establish a factory on the West Coast for the production of critically needed sapphire jewel bearings. This was to be one of the five such jewel bearing manufacturing plants to be established in the United States. The specialized equipment required for this undertaking and the specialized manufacturing know how was to be provided to the company by the Government. Louis Levin agreed to expand his business and create a manufacturing facility in Los Angeles that would produce finished sapphire jewel bearings for the Navy. In 1942, Louis Levin and Son, Inc. established a new factory in Los Angeles near the intersection of Beverly Boulevard and Alvarado. At the time the contract was signed, neither Louis nor Samuel Levin actually knew how to mass produce sapphire jewel bearings. They were operating under the belief that both the equipment and instructions they were to receive from the Government would be sufficient to enable them to proceed. Unfortunately, neither the equipment nor the technical know how provided by the Government through its prime contractor was adequate for the task at hand. The Levins and their staff found it necessary to modify and improve both the manufacturing equipment provided by the Navy and the manufacturing process furnished by them. It took some time; but ultimately Louis Levin & Son, Inc. began shipping finished sapphire jewel bearings that were as good as those imported from the leading manufacturers in Switzerland. Louis Levin & Son, Inc. continued production of jewel bearings until "V-J Day". It was during this period that three generations of family members were at work in the company. Sam's sister Ann and her husband William Freedman went to work full time in the Jewell Bearing Department of the company. Their daughter, Sylvia, a young school aged child worked in the plant on a part time basis. Sam's son Bob, also a school aged child, worked in the plant on a part time basis. These two grandchildren of Louis Levin, who had appeared together on the cover of the December 1939 issue of Horology were now spending their free time working for the war effort. After the war, a well illustrated description of the jewel bearing manufacturing process at the Levin factory was included in later editions of Louis and Samuel Levin's book, Practical Benchwork For Horologists.

In an address before the Horological Association of California in late 1938, Samuel Levin presented a talk on "The Lathe and Its Use". This talk was later reprinted in the December 1938 edition of Horology and includes numerous photographs and drawings made by Samuel Levin. As Horology began its sixth year of publication in April of 1939, it announced that it had attracted more than 5000 subscribers. In 1939 Louis Levin was awarded an honorary membership in the Horological Institute of America for his activities on behalf of that organization. Both Louis and Samuel continued to promote the goal of state licensing legislation for the profession of horology and for the establishment of appropriate standards and tests for those who wish to refer to themselves horologists. By this time the magazine stated that the name Horologist "is gradually becoming a recognized name for one who is an expert on timepieces".

The two Levins designed and manufactured many special tools for their own use. Some were required to enable them to accurately replicate damaged or worn parts in rare timepieces entrusted to them for repair and service. Others were necessary for the production of parts for the many special devices and mechanisms they were engaged to manufacture, including specialized tools used by horologists for the repair of timepieces. Often these tools were carefully photographed and articles describing how to design manufacture and use them would appear in Horology. Louis and Samuel Levin made every effort to educate horologists throughout the country on how to make the best possible tools of their trade, how to use them, and how to take care of them. They also presented articles and gave talks on how to repair and regulate watches. Their writings and illustrations covering the design, use and care of the watchmaker's lathe were so thorough and so complete as to have been incorporated in later books and manuals by other authors.

Over the years, the Louis Levin & Son designed and manufactured a wide variety of mechanisms, ranging in application from the control of one of the first automatic traffic signals in Los Angeles, a mechanical synchronizer for use in flash photography, a device which, when dropped down an oil well hole, recorded the direction of the hole and a mechanically powered trephine for use by ophthalmologists in cutting out a cork shaped section of a cornea during corneal transplant surgery. In order to publish their magazine, design and manufacture special mechanisms and repair time pieces, they needed to add considerable equipment to their downtown office of Horology. By 1940, their office was equipped with a nine inch engine lathe, a small milling machine with a dividing head, several watchmakers' lathes, a watch rate recorder, a small offset printing press, a couple of typewriters, a microscope, and several cameras equipped with special adapters enabling them to photograph the smallest watch parts through their microscope. These special optical devices were designed and manufactured by them and used to take many of the remarkable pictures appearing in both Horology and Practical Benchwork For Horologists.