After the war, Conn returned to Elkhart and established a grocery and baking business. He also played cornet in the local community band. Conn's entrance into the musical instrument manufacturing business was the result of a split lip. There are three existing stories of how this occurred, but the popularly accepted version is that Del Crampton slugged him in the mouth outside a saloon where both of them had been drinking. Conn's upper lip was severely lacerated, and it pained him so to play his cornet that he thought his playing days were over. In addition to running his store, Conn also made rubber stamps and re-plated silverware. He decided to try adhering rubber stamp material to the rim of a mouthpiece which he hoped would conform to his lips. After he showed his friends his idea, he realized that there was tremendous demand for his invention. Conn then began to contemplate manufacturing his new mouthpiece. He needed a rim with a groove which the rubber cement would adhere to more easily. It was in 1874 when Conn converted a discarded sewing machine frame into a simple lathe and started to turn out his mouthpieces and was soon in full production (Subsequently, Conn and Del Crampton became best of friends, and when Conn embarked on his political career, he was a staunch advocate of temperance).