The Waltham Machine Works Company was founded by Benjamin F. Ellis and Edmund L. Sanderson in 1898, both men having previously had long experience of the watch and clock trade and its associated high-quality engineering. Benjamin Ellis was born in Plymouth, Massachusetts and, from 1881, worked at the American Watch Tool Company being, for the most part, in charge of the sub-press die department. Mr. Edmund Sanderson, a native of Waltham, began work in the design department of the same company in 1884 and, apart from one year working for two other companies, stayed with them until he started the business venture with his co-worker.
     Following a management and product change at the Watch Tool Company (following the death of one of the owners, Ambrose Webster) and taking note of the excellent trading conditions, Ellis and Sanderson decided to open their own machine shop specialising in the very highest quality work.
     A small factory, made of wood, was built at the junction of Cutter Street and Newton Street and on September 1st. 1898, the undertaking started business with one machinist, an apprentice - and one solitary order. In December of the same year the Company was named "The Waltham Machine Works" and business began to grow slowly but steadily. Happily, within just a few years, and in common with many other machine-tool makers of the time, they had completely outgrown their modest hut and took the opportunity to buy the machinery, tools and good-will of the nearby Alcorn Machine Company when it came on the market in January 1902. The Alcorn factory building was also leased, and run in connection with the original building, whilst another machine shop was briefly opened in Boston.
     In 1903  a brick extension was added to the east side of the wooden building and the leased building abandoned. In 1914 the wooden building was moved to the south east corner of the building plot and replaced by a two-storied brick building that was joined to the original extension.
     The factory's first work, and much of that done during its first few years, was concerned with making sub-presses and dies. Because their operations required a substantial but accurate bench lathe, Ellis and Sanderson decided to design and build one to their own specification - and no doubt hoped (correctly as it turned out) that it would prove as marketable a product as the original Stark and Watch Tool Company models (introduced many years previously) and would appeal to shops similar to their own - as well as to the increasing numbers of self-employed instrument, watch, clock and optical mechanics.

The first batch of lathes was completed in September 1899 and one of these was sold in Switzerland through the agency of L. Ariste Gindrat, a Swiss citizen who had lived in Waltham and had an intimate knowledge of the town's machine shops and their ability to turn out work of the highest quality. As result of that initial sale, over one hundred precision lathes were sold in Switzerland during the following years and, as Waltham's reputation spread to the watch and clock makers and repairers of France and Germany orders for standard and special machines began to arrive from them as well. For the first ten or fifteen years of the Company's existence. a large percentage of its total output was sent abroad; however, the first export order came from England, in 1899.
     Apart from lathes, a range of other special machines was made, including, in 1899, an automatic gear cutting machine, the design of which became so popular that for many years it was the one of the most important items in the Waltham Machine Works' catalogue.
     In 1910,  Mr. F.O.Wells, of Wells Brothers Company of Greenfield, suggested that Waltham design a small machine for milling threads on gauges and, so successful was this new product, that the design was quickly adapted to make it more suitable for general work, and many examples were sold.
In 1914, at the outbreak of the First World War, sales to continental Europe collapsed, but greatly increased orders from Great Britain offset this loss to a large extent. In addition, thread-milling and gear-cutting machines were in great demand in the USA and the factory found no difficulty in obtaining work manufacturing critically-dimensioned tools and gauges for the munitions trade.
     Even though newly enlarged, the factory was soon too small to absorb the vastly increased demand and as a result the manufacture of bench lathes ceased and work was concentrated in areas where the factory's strengths in design and workmanship could be most profitably employed. After the hectic war years the factory continued to exploit its ability to design and manufacture, to the very highest standards and tightest tolerances, thread-milling and gear-cutting machines, sub-presses and dies - as well as undertaking complex commissions to design and build one-off machines for special purposes. The Waltham Machine Works were, it was said, were the toolmaker's Toolmaker.
     Besides building milling and gear-cutting machines, Waltham had also made the cutters to use in them and, during 1918, the original wooden building was restored and equipped with production machinery to increase the output of these tools. In 1924 the word "Waltham" was granted as a Trade Mark, and registered at the US Patent Office.
     The late 1920s and early 1930s, the years of the "great depression", were especially difficult for machine-tool makers and it was at this time that the conservative Waltham policy of holding back a large portion of profits for future emergencies enabled them to use their highly-skilled workmen to make newly-designed machines for the factory's own use, and in repairing and rebuilding its mechanical equipment, so as to be ready for the next upturn in trade.
     World War Two brought increased activity and, once again, the factory proved too small to handle all the work they were offered. On December 1st. 1941, Mr. Ellis, who was in failing health, sold his half of the business to his partner and Edward Blake of Newton, head of a sales organisation specialising in small machines and tools - who also marketed a machine built for him by Waltham for the relief sharpening of the chamfer on taps.  So ended a partnership of over forty-three years - Mr. Ellis died in January 1942.
     During the war another much more complex machine, for grinding the flutes of taps was also designed and built for Mr Blake after he became a full partner and this successful machine enjoyed wide sales. The pressures of war work finally forced another break with the past when the company ceased production of its original product - precision punches and dies - that had always been under the direct and personal supervision of Mr. Ellis
     In October 1947 Mr. Blake withdrew from the firm to devote all of his time to his sales business and the Waltham Machine Works were then carried on by Mr. Sanderson, now the sole owner.
From the firm's earliest days the designing and building of special machines was a central part of their activities and lathes and other machines that became part of the regular product line were all designed by the owners, who also conceived and made many of the machine tools required for production within the factory. During the first fifty years of the small Company's life more than 160 different precision, special-purpose machines had been designed and built, in addition to many others to customers' drawings.   
     On December 30th. 1948  the company was restructured as the Waltham Machine Works, Inc., and formed with the intention of taking over the business of Waltham Machine Works; however, due to problems with the mortgagee, this was not done until June 15th. 1952,  when the transfer was made and Mr. Sanderson became president and treasurer. In May Mr. George W. Hoar purchased all of Mr. Sanderson's stock in the corporation and the directors elected George W. Hoar treasurer, and his son, Norman W. Hoar, president. Mr. Sanderson had been partner, owner or president of the Waltham Machine Works for over fifty-seven years.