He was one of the young white Chicagoans who fell in love with jazz as a result of hearing King Oliver's band (with Louis Armstrong on second cornet) at the Lincoln Gardens in Chicago in the early 1920s. Oliver's drummer, Baby Dodds, made a particular and lasting impression upon Wettling.
Wettling went on to work with the big bands of Artie Shaw, Bunny Berigan, Red Norvo, Paul Whiteman, and even Harpo Marx: but he was at his best on (and will be best remembered for) his work in small 'hot' bands led by Eddie Condon, Muggsy Spanier, and himself. In these small bands, Wettling was able to demonstrate the arts of dynamics and responding to a particular soloist that he had learned from Baby Dodds.
Wettling was a member of some of Condon's classic line-ups, which included, among others, Wild Bill Davison, Billy Butterfield, Edmond Hall, Peanuts Hucko, Pee Wee Russell, Cutty Cutshall, Gene Schroeder, Ralph Sutton, and Walter Page, and in 1957 toured Britain with a Condon band including Davison, Cutshall, and Schroeder.
Towards the end of his life, Wettling (like his friend the clarinetist Pee Wee Russell), took up painting, and was much influenced by the American cubist Stuart Davis. He has been said to have believed that "jazz drumming and abstract painting seemed different for him only from the point of view of craftsmanship: in both fields he felt rhythm to be decisive".