Flemming invented a guitar he called the "Euphonica" that he believed would produce a louder and more resonant sound than a traditional guitar. The U.S. Patent Office granted Flemming a patent (no. 338,727) on March 30, 1886. He also received a Canadian patent (no. 26,398) on April 5, 1887. Flemming then went into business for himself, building and demonstrating his musical instruments from a storefront on Washington Street in Boston. After 1900, Robert Flemming retired to his home in Melrose, Massachusetts, where he continued to give lessons and perform at various functions. In 1907, he composed a "National Funeral Hymn" dedicated to the Grand Army of the Republic A member of the Grand Army of the Republic Post no. 30 in Cambridge, Massachusetts, Robert Flemming died in February 1919.