In strict terms a fettler is someone whose job it is to sand and grind small imperfections from metal and ceramic castings. In more general terms, it has come to mean someone who fiddles/tinkers with things (e.g. "I've spent all day fettling with my car").

Anecdotal Information

In Lancashire, fettler has been used as a term for friend or mate (e.g. "How's tha' doing fettler?") for many years, and has now passed firmly into the dialect.

To maintain the tracks of the Trans-Australian Railway, running across the barren Nullarbor Plain from Port Augusta in Southern Australia to Kalgoorlie in Western Australia, outback settlements were established along the line to accommodate a permanent workforce called the settlers. In the days when the line was built (construction began in 1917), settlers was still written with the then obsolete long s, also known as medial or descending s (ʃ), a minuscule version of the letter s, resulting in the term ʃettlers. In time, the long s (ʃ) got confused with the letter f. Thus, according to Australian legend, ʃettlers was apparently misinterpreted as fettlers.

Union song about Fettlers