 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 1946 , the two brothers received the Edward Longstreth Medal of the Franklin Institute as recognition for this accomplishment . They had improved the accurate manufacture of die @-@ cut screws in soft metal and solved the problem of thread @-@ grinding on hardened work . 
