Flanders and his brother, Ernest, were instrumental in developing screw thread grinding machines. These incorporated advances in thread technology (furthered by the Hartness optical comparator) and Flanders's engineering calculations for gear-cutting machinery. In 1942, the two brothers received the Edward Longstreth Medal of the Franklin Institute as recognition of this accomplishment, which improved the accurate manufacture of die-cut screws in soft metal and solved the problem of thread-grinding on hardened work. The award also recognized their development of a precision grinding machine that enabled rapid production of turbine blades at the start of jet aircraft age, which made it possible for companies including General Electric to manufacture jet engines far more quickly than they could previously.