In what became training for their futures in manufacturing, Stewart and Thomas J. Clark worked at a factory in New Hampshire that produced horse clipping machinery.
The lifelong friends later moved to Providence, Rhode Island, and worked for the Brown & Sharpe Manufacturing Company.
In 1910, the Chicago Flexible Shaft Company introduced its first home appliance, an electric iron, under the brand name Sunbeam.
Around 1896 Stewart and Clark founded the Sterk Manufacturing Company which produced speedometers and automobile horns.
This plant would eventually grow to a one million square foot (93,000 m2) manufacturing and headquarters facility for Stewart-Warner until the company left Chicago in 1988.
Due to the need for the blades of clippers & shears to last longer and remain sharp, Stewart worked with Edward Larson to build a heat treatment furnace for tempering steel.
Eventually becoming a division of Stewart-Warner, the phonograph company expanded to include radios, televisions, and the required accessories such as speakers.